## 1. Project Overview & Quickstart (docker/cli) ## File: README.md # Docker CLI [](https://pkg.go.dev/github.com/docker/cli) [](https://github.com/docker/cli/actions?query=workflow%3Abuild) [](https://github.com/docker/cli/actions?query=workflow%3Atest) [](https://scorecard.dev/viewer/?uri=github.com/docker/cli) [](https://codecov.io/gh/docker/cli) ## About This repository is the home of the Docker CLI. ## Development `docker/cli` is developed using Docker. Build CLI from source: ```shell docker buildx bake ``` Build binaries for all supported platforms: ```shell docker buildx bake cross ``` Build for a specific platform: ```shell docker buildx bake --set binary.platform=linux/arm64 ``` Build dynamic binary for glibc or musl: ```shell USE_GLIBC=1 docker buildx bake dynbinary ``` Run all linting: ```shell docker buildx bake lint shellcheck ``` Run test: ```shell docker buildx bake test ``` Run the unit test: ``` $ make -f docker.Makefile test-unit ``` Run the full test suite: ``` $ make -f docker.Makefile test ``` List all the available targets: ```shell make help ``` ### In-container development environment Start an interactive development environment: ```shell make shell ``` ## Legal *Brought to you courtesy of our legal counsel. For more context, see the [NOTICE](https://github.com/docker/cli/blob/master/NOTICE) document in this repo.* Use and transfer of Docker may be subject to certain restrictions by the United States and other governments. It is your responsibility to ensure that your use and/or transfer does not violate applicable laws. For more information, see https://www.bis.doc.gov ## Licensing docker/cli is licensed under the Apache License, Version 2.0. See [LICENSE](https://github.com/docker/docker/blob/master/LICENSE) for the full license text. --- ## File: docs/extend/_index.md --- title: Docker Engine managed plugin system linkTitle: Docker Engine plugins keywords: "API, Usage, plugins, documentation, developer" aliases: - "/engine/extend/plugins_graphdriver/" --- - [Installing and using a plugin](index.md#installing-and-using-a-plugin) - [Developing a plugin](index.md#developing-a-plugin) - [Debugging plugins](index.md#debugging-plugins) Docker Engine's plugin system lets you install, start, stop, and remove plugins using Docker Engine. For information about legacy (non-managed) plugins, refer to [Understand legacy Docker Engine plugins](legacy_plugins.md). > [!NOTE] > Docker Engine managed plugins are currently not supported on Windows daemons. ## Installing and using a plugin Plugins are distributed as Docker images and can be hosted on Docker Hub or on a private registry. To install a plugin, use the `docker plugin install` command, which pulls the plugin from Docker Hub or your private registry, prompts you to grant permissions or capabilities if necessary, and enables the plugin. To check the status of installed plugins, use the `docker plugin ls` command. Plugins that start successfully are listed as enabled in the output. After a plugin is installed, you can use it as an option for another Docker operation, such as creating a volume. In the following example, you install the [`rclone` plugin](https://rclone.org/docker/), verify that it is enabled, and use it to create a volume. > [!NOTE] > This example is intended for instructional purposes only. 1. Set up the pre-requisite directories. By default they must exist on the host at the following locations: - `/var/lib/docker-plugins/rclone/config`. Reserved for the `rclone.conf` config file and must exist even if it's empty and the config file is not present. - `/var/lib/docker-plugins/rclone/cache`. Holds the plugin state file as well as optional VFS caches. 2. Install the `rclone` plugin. ```console $ docker plugin install rclone/docker-volume-rclone --alias rclone Plugin "rclone/docker-volume-rclone" is requesting the following privileges: - network: [host] - mount: [/var/lib/docker-plugins/rclone/config] - mount: [/var/lib/docker-plugins/rclone/cache] - device: [/dev/fuse] - capabilities: [CAP_SYS_ADMIN] Do you grant the above permissions? [y/N] ``` The plugin requests 5 privileges: - It needs access to the `host` network. - Access to pre-requisite directories to mount to store: - Your Rclone config files - Temporary cache data - Gives access to the FUSE (Filesystem in Userspace) device. This is required because Rclone uses FUSE to mount remote storage as if it were a local filesystem. - It needs the `CAP_SYS_ADMIN` capability, which allows the plugin to run the `mount` command. 2. Check that the plugin is enabled in the output of `docker plugin ls`. ```console $ docker plugin ls ID NAME DESCRIPTION ENABLED aede66158353 rclone:latest Rclone volume plugin for Docker true ``` 3. Create a volume using the plugin. This example mounts the `/remote` directory on host `1.2.3.4` into a volume named `rclonevolume`. This volume can now be mounted into containers. ```console $ docker volume create \ -d rclone \ --name rclonevolume \ -o type=sftp \ -o path=remote \ -o sftp-host=1.2.3.4 \ -o sftp-user=user \ -o "sftp-password=$(cat file_containing_password_for_remote_host)" ``` 4. Verify that the volume was created successfully. ```console $ docker volume ls DRIVER NAME rclone rclonevolume ``` 5. Start a container that uses the volume `rclonevolume`. ```console $ docker run --rm -v rclonevolume:/data busybox ls /data ``` 6. Remove the volume `rclonevolume` ```console $ docker volume rm rclonevolume sshvolume ``` To disable a plugin, use the `docker plugin disable` command. To completely remove it, use the `docker plugin remove` command. For other available commands and options, see the [command line reference](https://docs.docker.com/reference/cli/docker/). ## Developing a plugin #### The rootfs directory The `rootfs` directory represents the root filesystem of the plugin. In this example, it was created from a Dockerfile: > [!NOTE] > The `/run/docker/plugins` directory is mandatory inside of the > plugin's filesystem for Docker to communicate with the plugin. ```console $ git clone https://github.com/vieux/docker-volume-sshfs $ cd docker-volume-sshfs $ docker build -t rootfsimage . $ id=$(docker create rootfsimage true) # id was cd851ce43a403 when the image was created $ sudo mkdir -p myplugin/rootfs $ sudo docker export "$id" | sudo tar -x -C myplugin/rootfs $ docker rm -vf "$id" $ docker rmi rootfsimage ``` #### The config.json file The `config.json` file describes the plugin. See the [plugins config reference](config.md). Consider the following `config.json` file. ```json { "description": "sshFS plugin for Docker", "documentation": "https://docs.docker.com/engine/extend/plugins/", "entrypoint": ["/docker-volume-sshfs"], "network": { "type": "host" }, "interface": { "types": ["docker.volumedriver/1.0"], "socket": "sshfs.sock" }, "linux": { "capabilities": ["CAP_SYS_ADMIN"] } } ``` This plugin is a volume driver. It requires a `host` network and the `CAP_SYS_ADMIN` capability. It depends upon the `/docker-volume-sshfs` entrypoint and uses the `/run/docker/plugins/sshfs.sock` socket to communicate with Docker Engine. This plugin has no runtime parameters. #### Creating the plugin A new plugin can be created by running `docker plugin create ./path/to/plugin/data` where the plugin data contains a plugin configuration file `config.json` and a root filesystem in subdirectory `rootfs`. After that the plugin `` will show up in `docker plugin ls`. Plugins can be pushed to remote registries with `docker plugin push `. ## Debugging plugins Stdout of a plugin is redirected to dockerd logs. Such entries have a `plugin=` suffix. Here are a few examples of commands for pluginID `f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62` and their corresponding log entries in the docker daemon logs. ```console $ docker plugin install tiborvass/sample-volume-plugin INFO[0036] Starting... Found 0 volumes on startup plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 ``` ```console $ docker volume create -d tiborvass/sample-volume-plugin samplevol INFO[0193] Create Called... Ensuring directory /data/samplevol exists on host... plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0193] open /var/lib/docker/plugin-data/local-persist.json: no such file or directory plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0193] Created volume samplevol with mountpoint /data/samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0193] Path Called... Returned path /data/samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 ``` ```console $ docker run -v samplevol:/tmp busybox sh INFO[0421] Get Called... Found samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0421] Mount Called... Mounted samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0421] Path Called... Returned path /data/samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 INFO[0421] Unmount Called... Unmounted samplevol plugin=f52a3df433b9aceee436eaada0752f5797aab1de47e5485f1690a073b860ff62 ``` #### Using runc to obtain logfiles and shell into the plugin. Use `runc`, the default docker container runtime, for debugging plugins by collecting plugin logs redirected to a file. ```console $ sudo runc --root /run/docker/runtime-runc/plugins.moby list ID PID STATUS BUNDLE CREATED OWNER 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 15806 running /run/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby-plugins/93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 2018-02-08T21:40:08.621358213Z root 9b4606d84e06b56df84fadf054a21374b247941c94ce405b0a261499d689d9c9 14992 running /run/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby-plugins/9b4606d84e06b56df84fadf054a21374b247941c94ce405b0a261499d689d9c9 2018-02-08T21:35:12.321325872Z root c5bb4b90941efcaccca999439ed06d6a6affdde7081bb34dc84126b57b3e793d 14984 running /run/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby-plugins/c5bb4b90941efcaccca999439ed06d6a6affdde7081bb34dc84126b57b3e793d 2018-02-08T21:35:12.321288966Z root ``` ```console $ sudo runc --root /run/docker/runtime-runc/plugins.moby exec 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 cat /var/log/plugin.log ``` If the plugin has a built-in shell, then exec into the plugin can be done as follows: ```console $ sudo runc --root /run/docker/runtime-runc/plugins.moby exec -t 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 sh ``` #### Using curl to debug plugin socket issues. To verify if the plugin API socket that the docker daemon communicates with is responsive, use curl. In this example, we will make API calls from the docker host to volume and network plugins using curl 7.47.0 to ensure that the plugin is listening on the said socket. For a well functioning plugin, these basic requests should work. Note that plugin sockets are available on the host under `/var/run/docker/plugins/` ```console $ curl -H "Content-Type: application/json" -XPOST -d '{}' --unix-socket /var/run/docker/plugins/e8a37ba56fc879c991f7d7921901723c64df6b42b87e6a0b055771ecf8477a6d/plugin.sock http:/VolumeDriver.List {"Mountpoint":"","Err":"","Volumes":[{"Name":"myvol1","Mountpoint":"/data/myvol1"},{"Name":"myvol2","Mountpoint":"/data/myvol2"}],"Volume":null} ``` ```console $ curl -H "Content-Type: application/json" -XPOST -d '{}' --unix-socket /var/run/docker/plugins/45e00a7ce6185d6e365904c8bcf62eb724b1fe307e0d4e7ecc9f6c1eb7bcdb70/plugin.sock http:/NetworkDriver.GetCapabilities {"Scope":"local"} ``` When using curl 7.5 and above, the URL should be of the form `http://hostname/APICall`, where `hostname` is the valid hostname where the plugin is installed and `APICall` is the call to the plugin API. For example, `http://localhost/VolumeDriver.List` --- ## File: docs/extend/config.md --- keywords: "API, Usage, plugins, documentation, developer" title: Plugin Config Version 1 of Plugin V2 --- This document outlines the format of the V0 plugin configuration. Plugin configs describe the various constituents of a Docker engine plugin. Plugin configs can be serialized to JSON format with the following media types: | Config Type | Media Type | |-------------|-----------------------------------------| | config | `application/vnd.docker.plugin.v1+json` | ## Config Field Descriptions Config provides the base accessible fields for working with V0 plugin format in the registry. - `description` string Description of the plugin - `documentation` string Link to the documentation about the plugin - `interface` PluginInterface Interface implemented by the plugins, struct consisting of the following fields: - `types` string array Types indicate what interface(s) the plugin currently implements. Supported types: - `docker.volumedriver/1.0` - `docker.networkdriver/1.0` - `docker.ipamdriver/1.0` - `docker.authz/1.0` - `docker.logdriver/1.0` - `docker.metricscollector/1.0` - `socket` string Socket is the name of the socket the engine should use to communicate with the plugins. the socket will be created in `/run/docker/plugins`. - `entrypoint` string array Entrypoint of the plugin, see [`ENTRYPOINT`](https://docs.docker.com/reference/dockerfile/#entrypoint) - `workdir` string Working directory of the plugin, see [`WORKDIR`](https://docs.docker.com/reference/dockerfile/#workdir) - `network` PluginNetwork Network of the plugin, struct consisting of the following fields: - `type` string Network type. Supported types: - `bridge` - `host` - `none` - `mounts` PluginMount array Mount of the plugin, struct consisting of the following fields. See [`MOUNTS`](https://github.com/opencontainers/runtime-spec/blob/master/config.md#mounts). - `name` string Name of the mount. - `description` string Description of the mount. - `source` string Source of the mount. - `destination` string Destination of the mount. - `type` string Mount type. - `options` string array Options of the mount. - `ipchost` Boolean Access to host ipc namespace. - `pidhost` Boolean Access to host PID namespace. - `propagatedMount` string Path to be mounted as rshared, so that mounts under that path are visible to Docker. This is useful for volume plugins. This path will be bind-mounted outside of the plugin rootfs so it's contents are preserved on upgrade. - `env` PluginEnv array Environment variables of the plugin, struct consisting of the following fields: - `name` string Name of the environment variable. - `description` string Description of the environment variable. - `value` string Value of the environment variable. - `args` PluginArgs Arguments of the plugin, struct consisting of the following fields: - `name` string Name of the arguments. - `description` string Description of the arguments. - `value` string array Values of the arguments. - `linux` PluginLinux - `capabilities` string array Capabilities of the plugin (Linux only), see list [`here`](https://github.com/opencontainers/runc/blob/master/libcontainer/SPEC.md#security) - `allowAllDevices` Boolean If `/dev` is bind mounted from the host, and allowAllDevices is set to true, the plugin will have `rwm` access to all devices on the host. - `devices` PluginDevice array Device of the plugin, (Linux only), struct consisting of the following fields. See [`DEVICES`](https://github.com/opencontainers/runtime-spec/blob/master/config-linux.md#devices). - `name` string Name of the device. - `description` string Description of the device. - `path` string Path of the device. ## Example Config The following example shows the 'tiborvass/sample-volume-plugin' plugin config. ```json { "Args": { "Description": "", "Name": "", "Settable": null, "Value": null }, "Description": "A sample volume plugin for Docker", "Documentation": "https://docs.docker.com/engine/extend/plugins/", "Entrypoint": [ "/usr/bin/sample-volume-plugin", "/data" ], "Env": [ { "Description": "", "Name": "DEBUG", "Settable": [ "value" ], "Value": "0" } ], "Interface": { "Socket": "plugin.sock", "Types": [ "docker.volumedriver/1.0" ] }, "Linux": { "Capabilities": null, "AllowAllDevices": false, "Devices": null }, "Mounts": null, "Network": { "Type": "" }, "PropagatedMount": "/data", "User": {}, "Workdir": "" } ``` --- ## File: docs/extend/EBS_volume.md --- keywords: "API, Usage, plugins, documentation, developer, amazon, ebs, rexray, volume" --- # Volume plugin for Amazon EBS ## A proof-of-concept Rexray plugin In this example, a simple Rexray plugin will be created for the purposes of using it on an Amazon EC2 instance with EBS. It is not meant to be a complete Rexray plugin. The example source is available at [https://github.com/tiborvass/rexray-plugin](https://github.com/tiborvass/rexray-plugin). To learn more about Rexray: [https://github.com/codedellemc/rexray](https://github.com/codedellemc/rexray) ## 1. Make a Docker image The following is the Dockerfile used to containerize rexray. ```dockerfile FROM debian:jessie RUN apt-get update && apt-get install -y --no-install-recommends wget ca-certificates RUN wget https://dl.bintray.com/emccode/rexray/stable/0.6.4/rexray-Linux-x86_64-0.6.4.tar.gz -O rexray.tar.gz && tar -xvzf rexray.tar.gz -C /usr/bin && rm rexray.tar.gz RUN mkdir -p /run/docker/plugins /var/lib/libstorage/volumes ENTRYPOINT ["rexray"] CMD ["--help"] ``` To build it you can run `image=$(cat Dockerfile | docker build -q -)` and `$image` will reference the containerized rexray image. ## 2. Extract rootfs ```sh $ TMPDIR=/tmp/rexray # for the purpose of this example $ # create container without running it, to extract the rootfs from image $ docker create --name rexray "$image" $ # save the rootfs to a tar archive $ docker export -o $TMPDIR/rexray.tar rexray $ # extract rootfs from tar archive to a rootfs folder $ ( mkdir -p $TMPDIR/rootfs; cd $TMPDIR/rootfs; tar xf ../rexray.tar ) ``` ## 3. Add plugin configuration We have to put the following JSON to `$TMPDIR/config.json`: ```json { "Args": { "Description": "", "Name": "", "Settable": null, "Value": null }, "Description": "A proof-of-concept EBS plugin (using rexray) for Docker", "Documentation": "https://github.com/tiborvass/rexray-plugin", "Entrypoint": [ "/usr/bin/rexray", "service", "start", "-f" ], "Env": [ { "Description": "", "Name": "REXRAY_SERVICE", "Settable": [ "value" ], "Value": "ebs" }, { "Description": "", "Name": "EBS_ACCESSKEY", "Settable": [ "value" ], "Value": "" }, { "Description": "", "Name": "EBS_SECRETKEY", "Settable": [ "value" ], "Value": "" } ], "Interface": { "Socket": "rexray.sock", "Types": [ "docker.volumedriver/1.0" ] }, "Linux": { "AllowAllDevices": true, "Capabilities": ["CAP_SYS_ADMIN"], "Devices": null }, "Mounts": [ { "Source": "/dev", "Destination": "/dev", "Type": "bind", "Options": ["rbind"] } ], "Network": { "Type": "host" }, "PropagatedMount": "/var/lib/libstorage/volumes", "User": {}, "WorkDir": "" } ``` Note a couple of points: - `PropagatedMount` is needed so that the docker daemon can see mounts done by the rexray plugin from within the container, otherwise the docker daemon is not able to mount a docker volume. - The rexray plugin needs dynamic access to host devices. For that reason, we have to give it access to all devices under `/dev` and set `AllowAllDevices` to true for proper access. - The user of this simple plugin can change only 3 settings: `REXRAY_SERVICE`, `EBS_ACCESSKEY` and `EBS_SECRETKEY`. This is because of the reduced scope of this plugin. Ideally other rexray parameters could also be set. ## 4. Create plugin `docker plugin create tiborvass/rexray-plugin "$TMPDIR"` will create the plugin. ```sh $ docker plugin ls ID NAME DESCRIPTION ENABLED 2475a4bd0ca5 tiborvass/rexray-plugin:latest A rexray volume plugin for Docker false ``` ## 5. Test plugin ```sh $ docker plugin set tiborvass/rexray-plugin EBS_ACCESSKEY=$AWS_ACCESSKEY EBS_SECRETKEY=$AWS_SECRETKEY` $ docker plugin enable tiborvass/rexray-plugin $ docker volume create -d tiborvass/rexray-plugin my-ebs-volume $ docker volume ls DRIVER VOLUME NAME tiborvass/rexray-plugin:latest my-ebs-volume $ docker run --rm -v my-ebs-volume:/volume busybox sh -c 'echo bye > /volume/hi' $ docker run --rm -v my-ebs-volume:/volume busybox cat /volume/hi bye ``` ## 6. Push plugin First, ensure you are logged in with `docker login`. Then you can run: `docker plugin push tiborvass/rexray-plugin` to push it like a regular docker image to a registry, to make it available for others to install via `docker plugin install tiborvass/rexray-plugin EBS_ACCESSKEY=$AWS_ACCESSKEY EBS_SECRETKEY=$AWS_SECRETKEY`. --- ## File: docs/extend/legacy_plugins.md --- title: Use Docker Engine plugins aliases: - "/engine/extend/plugins/" keywords: "Examples, Usage, plugins, docker, documentation, user guide" --- This document describes the Docker Engine plugins generally available in Docker Engine. To view information on plugins managed by Docker, refer to [Docker Engine plugin system](_index.md). > [!NOTE] > Legacy plugins are superseded by Docker Engine's managed plugin system. > For plugins installed and managed by Docker, use > [`docker plugin install`](https://docs.docker.com/reference/cli/docker/plugin/install/) > and the [Docker Engine plugin system](_index.md). The third-party plugins > listed on this page are provided for historical reference, and archived > projects are marked accordingly. You can extend the capabilities of the Docker Engine by loading third-party plugins. This page explains the types of plugins and provides links to several volume and network plugins for Docker. ## Types of plugins Plugins extend Docker's functionality. They come in specific types. For example, a [volume plugin](plugins_volume.md) might enable Docker volumes to persist across multiple Docker hosts and a [network plugin](plugins_network.md) might provide network plumbing. Currently Docker supports authorization, volume and network driver plugins. In the future it will support additional plugin types. ## Installing a plugin Follow the instructions in the plugin's documentation. ## Finding a plugin The sections below provide an overview of third-party plugins that use the legacy plugin model. ### Network plugins | Plugin | Description | | :--------------------------------------------------------------------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [Contiv Networking](https://github.com/contiv/netplugin) | An open source network plugin to provide infrastructure and security policies for a multi-tenant micro services deployment, while providing an integration to physical network for non-container workload. Contiv Networking implements the remote driver and IPAM APIs available in Docker 1.9 onwards. | | [Kuryr Network Plugin](https://github.com/openstack/kuryr) | A network plugin is developed as part of the OpenStack Kuryr project and implements the Docker networking (libnetwork) remote driver API by utilizing Neutron, the OpenStack networking service. It includes an IPAM driver as well. | | [Kathará Network Plugin](https://github.com/KatharaFramework/NetworkPlugin) | Docker Network Plugin used by Kathará, an open source container-based network emulation system for showing interactive demos/lessons, testing production networks in a sandbox environment, or developing new network protocols. | ### Volume plugins | Plugin | Description | |:---------------------------------------------------------------------------------------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Azure File Storage plugin](https://github.com/Azure/azurefile-dockervolumedriver) (archived) | Lets you mount Microsoft [Azure File Storage](https://azure.microsoft.com/blog/azure-file-storage-now-generally-available/) shares to Docker containers as volumes using the SMB 3.0 protocol. [Learn more](https://azure.microsoft.com/blog/persistent-docker-volumes-with-azure-file-storage/). | | [BeeGFS Volume Plugin](https://github.com/RedCoolBeans/docker-volume-beegfs) | An open source volume plugin to create persistent volumes in a BeeGFS parallel file system. | | [Blockbridge plugin](https://github.com/blockbridge/blockbridge-docker-volume) | A volume plugin that provides access to an extensible set of container-based persistent storage options. It supports single and multi-host Docker environments with features that include tenant isolation, automated provisioning, encryption, secure deletion, snapshots and QoS. | | [Contiv Volume Plugin](https://github.com/contiv/volplugin) | An open source volume plugin that provides multi-tenant, persistent, distributed storage with intent based consumption. It has support for Ceph and NFS. | | [Convoy plugin](https://github.com/rancher/convoy) (archived) | A volume plugin for a variety of storage back-ends including device mapper and NFS. It's a simple standalone executable written in Go and provides the framework to support vendor-specific extensions such as snapshots, backups and restore. | | [DigitalOcean Block Storage plugin](https://github.com/omallo/docker-volume-plugin-dostorage) | Integrates DigitalOcean's [block storage solution](https://www.digitalocean.com/products/storage/) into the Docker ecosystem by automatically attaching a given block storage volume to a DigitalOcean droplet and making the contents of the volume available to Docker containers running on that droplet. | | [DRBD plugin](https://www.drbd.org/en/supported-projects/docker) | A volume plugin that provides highly available storage replicated by [DRBD](https://www.drbd.org). Data written to the docker volume is replicated in a cluster of DRBD nodes. | | [Flocker plugin](https://github.com/ScatterHQ/flocker) (archived) | A volume plugin that provides multi-host portable volumes for Docker, enabling you to run databases and other stateful containers and move them around across a cluster of machines. | | [Fuxi Volume Plugin](https://github.com/openstack-archive/fuxi) (archived) | A volume plugin that is developed as part of the OpenStack Kuryr project and implements the Docker volume plugin API by utilizing Cinder, the OpenStack block storage service. | | [gce-docker plugin](https://github.com/mcuadros/gce-docker) (archived) | A volume plugin able to attach, format and mount Google Compute [persistent-disks](https://cloud.google.com/compute/docs/disks/persistent-disks). | | [GlusterFS plugin](https://github.com/calavera/docker-volume-glusterfs) (archived) | A volume plugin that provides multi-host volumes management for Docker using GlusterFS. | | [Horcrux Volume Plugin](https://github.com/muthu-r/horcrux) | A volume plugin that allows on-demand, version controlled access to your data. Horcrux is an open-source plugin, written in Go, and supports SCP, [Minio](https://www.minio.io) and Amazon S3. | | [HPE 3Par Volume Plugin](https://github.com/hpe-storage/python-hpedockerplugin/) | A volume plugin that supports HPE 3Par and StoreVirtual iSCSI storage arrays. | | [IPFS Volume Plugin](https://github.com/vdemeester/docker-volume-ipfs) (archived) | An open source volume plugin that allows using an [ipfs](https://ipfs.io/) filesystem as a volume. | | [Keywhiz plugin](https://github.com/calavera/docker-volume-keywhiz) (archived) | A plugin that provides credentials and secret management using Keywhiz as a central repository. | | [Linode Volume Plugin](https://github.com/linode/docker-volume-linode) | A plugin that adds the ability to manage Linode Block Storage as Docker Volumes from within a Linode. | | [Local Persist Plugin](https://github.com/CWSpear/local-persist) | A volume plugin that extends the default `local` driver's functionality by allowing you specify a mountpoint anywhere on the host, which enables the files to *always persist*, even if the volume is removed via `docker volume rm`. | | [NetApp Plugin](https://github.com/NetApp/netappdvp) (nDVP) | A volume plugin that provides direct integration with the Docker ecosystem for the NetApp storage portfolio. The nDVP package supports the provisioning and management of storage resources from the storage platform to Docker hosts, with a robust framework for adding additional platforms in the future. | | [Netshare plugin](https://github.com/ContainX/docker-volume-netshare) | A volume plugin that provides volume management for NFS 3/4, AWS EFS and CIFS file systems. | | [Nimble Storage Volume Plugin](https://scod.hpedev.io/docker_volume_plugins/hpe_nimble_storage/index.html) | A volume plug-in that integrates with Nimble Storage Unified Flash Fabric arrays. The plug-in abstracts array volume capabilities to the Docker administrator to allow self-provisioning of secure multi-tenant volumes and clones. | | [OpenStorage Plugin](https://github.com/libopenstorage/openstorage) | A cluster-aware volume plugin that provides volume management for file and block storage solutions. It implements a vendor neutral specification for implementing extensions such as CoS, encryption, and snapshots. It has example drivers based on FUSE, NFS, NBD and EBS to name a few. | | [Portworx Volume Plugin](https://github.com/portworx/px-dev) | A volume plugin that turns any server into a scale-out converged compute/storage node, providing container granular storage and highly available volumes across any node, using a shared-nothing storage backend that works with any docker scheduler. | | [Quobyte Volume Plugin](https://github.com/quobyte/docker-volume) | A volume plugin that connects Docker to [Quobyte](https://www.quobyte.com/containers)'s data center file system, a general-purpose scalable and fault-tolerant storage platform. | | [REX-Ray plugin](https://github.com/emccode/rexray) | A volume plugin which is written in Go and provides advanced storage functionality for many platforms including VirtualBox, EC2, Google Compute Engine, OpenStack, and EMC. | | [Virtuozzo Storage and Ploop plugin](https://github.com/virtuozzo/docker-volume-ploop) | A volume plugin with support for Virtuozzo Storage distributed cloud file system as well as ploop devices. | | [VMware vSphere Storage Plugin](https://github.com/vmware/docker-volume-vsphere) | Docker Volume Driver for vSphere enables customers to address persistent storage requirements for Docker containers in vSphere environments. | ### Authorization plugins | Plugin | Description | |:---------------------------------------------------------------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [Casbin AuthZ Plugin](https://github.com/casbin/casbin-authz-plugin) | An authorization plugin based on [Casbin](https://github.com/casbin/casbin), which supports access control models like ACL, RBAC, ABAC. The access control model can be customized. The policy can be persisted into file or DB. | | [HBM plugin](https://github.com/kassisol/hbm) | An authorization plugin that prevents from executing commands with certains parameters. | | [Twistlock AuthZ Broker](https://github.com/twistlock/authz) | A basic extendable authorization plugin that runs directly on the host or inside a container. This plugin allows you to define user policies that it evaluates during authorization. Basic authorization is provided if Docker daemon is started with the --tlsverify flag (username is extracted from the certificate common name). | ## Troubleshooting a plugin If you are having problems with Docker after loading a plugin, ask the authors of the plugin for help. The Docker team may not be able to assist you. ## Writing a plugin If you are interested in writing a plugin for Docker, or seeing how they work under the hood, see the [Docker plugins reference](plugin_api.md). --- ## File: docs/extend/plugin_api.md --- title: Docker Plugin API keywords: "API, Usage, plugins, documentation, developer" --- Docker plugins are out-of-process extensions which add capabilities to the Docker Engine. This document describes the Docker Engine plugin API. To view information on plugins managed by Docker Engine, refer to [Docker Engine plugin system](_index.md). This page is intended for people who want to develop their own Docker plugin. If you just want to learn about or use Docker plugins, look [here](legacy_plugins.md). ## What plugins are A plugin is a process running on the same or a different host as the Docker daemon, which registers itself by placing a file on the daemon host in one of the plugin directories described in [Plugin discovery](#plugin-discovery). Plugins have human-readable names, which are short, lowercase strings. For example, `myplugin`. Plugins can run inside or outside containers. Currently running them outside containers is recommended. ## Plugin discovery Docker discovers plugins by looking for them in the plugin directory whenever a user or container tries to use one by name. There are three types of files which can be put in the plugin directory. * `.sock` files are Unix domain sockets. * `.spec` files are text files containing a URL, such as `unix:///other.sock` or `tcp://localhost:8080`. * `.json` files are text files containing a full json specification for the plugin. Plugins with Unix domain socket files must run on the same host as the Docker daemon. Plugins with `.spec` or `.json` files can run on a different host if you specify a remote URL. Unix domain socket files must be located under `/run/docker/plugins`, whereas spec files can be located either under `/etc/docker/plugins` or `/usr/lib/docker/plugins`. The name of the file (excluding the extension) determines the plugin name. For example, a plugin named `myplugin` might create a Unix socket at `/run/docker/plugins/myplugin.sock`. You can define each plugin into a separated subdirectory if you want to isolate definitions from each other. For example, you can create the `myplugin` socket under `/run/docker/plugins/myplugin/myplugin.sock` and only mount `/run/docker/plugins/myplugin` inside the `myplugin` container. Docker always searches for Unix sockets in `/run/docker/plugins` first. It checks for spec or json files under `/etc/docker/plugins` and `/usr/lib/docker/plugins` if the socket doesn't exist. The directory scan stops as soon as it finds the first plugin definition with the given name. ### JSON specification This is the JSON format for a plugin: ```json { "Name": "plugin-example", "Addr": "https://example.com/docker/plugin", "TLSConfig": { "InsecureSkipVerify": false, "CAFile": "/usr/shared/docker/certs/example-ca.pem", "CertFile": "/usr/shared/docker/certs/example-cert.pem", "KeyFile": "/usr/shared/docker/certs/example-key.pem" } } ``` The `TLSConfig` field is optional and TLS will only be verified if this configuration is present. ## Plugin lifecycle Plugins should be started before Docker, and stopped after Docker. For example, when packaging a plugin for a platform which supports `systemd`, you might use [`systemd` dependencies]( https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Before=) to manage startup and shutdown order. When upgrading a plugin, you should first stop the Docker daemon, upgrade the plugin, then start Docker again. ## Plugin activation When a plugin is first referred to -- either by a user referring to it by name (e.g. `docker run --volume-driver=foo`) or a container already configured to use a plugin being started -- Docker looks for the named plugin in the plugin directory and activates it with a handshake. See Handshake API below. Plugins are not activated automatically at Docker daemon startup. Rather, they are activated only lazily, or on-demand, when they are needed. ## Systemd socket activation Plugins may also be socket activated by `systemd`. The official [Plugins helpers](https://github.com/docker/go-plugins-helpers) natively supports socket activation. In order for a plugin to be socket activated it needs a `service` file and a `socket` file. The `service` file (for example `/lib/systemd/system/your-plugin.service`): ```systemd [Unit] Description=Your plugin Before=docker.service After=network.target your-plugin.socket Requires=your-plugin.socket docker.service [Service] ExecStart=/usr/lib/docker/your-plugin [Install] WantedBy=multi-user.target ``` The `socket` file (for example `/lib/systemd/system/your-plugin.socket`): ```systemd [Unit] Description=Your plugin [Socket] ListenStream=/run/docker/plugins/your-plugin.sock [Install] WantedBy=sockets.target ``` This will allow plugins to be actually started when the Docker daemon connects to the sockets they're listening on (for instance the first time the daemon uses them or if one of the plugin goes down accidentally). ## API design The Plugin API is RPC-style JSON over HTTP, much like webhooks. Requests flow from the Docker daemon to the plugin. The plugin needs to implement an HTTP server and bind this to the Unix socket mentioned in the "plugin discovery" section. All requests are HTTP `POST` requests. The API is versioned via an Accept header, which currently is always set to `application/vnd.docker.plugins.v1+json`. ## Handshake API Plugins are activated via the following "handshake" API call. ### /Plugin.Activate Request: empty body Response: ```json { "Implements": ["VolumeDriver"] } ``` Responds with a list of Docker subsystems which this plugin implements. After activation, the plugin will then be sent events from this subsystem. Possible values are: * [`authz`](plugins_authorization.md) * [`NetworkDriver`](plugins_network.md) * [`VolumeDriver`](plugins_volume.md) ## Plugin retries Attempts to call a method on a plugin are retried with an exponential backoff for up to 30 seconds. This may help when packaging plugins as containers, since it gives plugin containers a chance to start up before failing any user containers which depend on them. ## Plugins helpers To ease plugins development, we're providing an `sdk` for each kind of plugins currently supported by Docker at [docker/go-plugins-helpers](https://github.com/docker/go-plugins-helpers). --- ## File: docs/extend/plugins_authorization.md --- title: Access authorization plugin keywords: "security, authorization, authentication, docker, documentation, plugin, extend" aliases: - "/engine/extend/authorization/" --- This document describes the Docker Engine plugins available in Docker Engine. To view information on plugins managed by Docker Engine, refer to [Docker Engine plugin system](_index.md). Docker's out-of-the-box authorization model is all or nothing. Any user with permission to access the Docker daemon can run any Docker client command. The same is true for callers using Docker's Engine API to contact the daemon. If you require greater access control, you can create authorization plugins and add them to your Docker daemon configuration. Using an authorization plugin, a Docker administrator can configure granular access policies for managing access to the Docker daemon. Anyone with the appropriate skills can develop an authorization plugin. These skills, at their most basic, are knowledge of Docker, understanding of REST, and sound programming knowledge. This document describes the architecture, state, and methods information available to an authorization plugin developer. ## Basic principles Docker's [plugin infrastructure](plugin_api.md) enables extending Docker by loading, removing and communicating with third-party components using a generic API. The access authorization subsystem was built using this mechanism. Using this subsystem, you don't need to rebuild the Docker daemon to add an authorization plugin. You can add a plugin to an installed Docker daemon. You do need to restart the Docker daemon to add a new plugin. An authorization plugin approves or denies requests to the Docker daemon based on both the current authentication context and the command context. The authentication context contains all user details and the authentication method. The command context contains all the relevant request data. Authorization plugins must follow the rules described in [Docker Plugin API](plugin_api.md). Each plugin must reside within directories described under the [Plugin discovery](plugin_api.md#plugin-discovery) section. > [!NOTE] > The abbreviations `AuthZ` and `AuthN` mean authorization and authentication > respectively. ## Default user authorization mechanism If TLS is enabled in the [Docker daemon](https://docs.docker.com/engine/security/https/), the default user authorization flow extracts the user details from the certificate subject name. That is, the `User` field is set to the client certificate subject common name, and the `AuthenticationMethod` field is set to `TLS`. ## Basic architecture You are responsible for registering your plugin as part of the Docker daemon startup. You can install multiple plugins and chain them together. This chain can be ordered. Each request to the daemon passes in order through the chain. Only when all the plugins grant access to the resource, is the access granted. When an HTTP request is made to the Docker daemon through the CLI or via the Engine API, the authentication subsystem passes the request to the installed authentication plugin(s). The request contains the user (caller) and command context. The plugin is responsible for deciding whether to allow or deny the request. The sequence diagrams below depict an allow and deny authorization flow: Each request sent to the plugin includes the authenticated user, the HTTP headers, and the request/response body. Only the user name and the authentication method used are passed to the plugin. Most importantly, no user credentials or tokens are passed. > [!NOTE] > Authorization plugins enforce requests to the Docker daemon's HTTP API only. gRPC method > calls, whether dispatched natively or upgraded through `POST /grpc`, are not subject to authorization. > Furthermore, HTTP request/response bodies where the `Content-Type` is `application/json` are forwarded; > bodies of any other type are not visible to the plugin and cannot be used for enforcement, > even though the daemon acts on this data. For commands that can potentially hijack the HTTP connection (`HTTP Upgrade`), such as `exec`, the authorization plugin is only called for the initial HTTP requests. Once the plugin approves the command, authorization is not applied to the rest of the flow. Specifically, the streaming data is not passed to the authorization plugins. For commands that return chunked HTTP response, such as `logs` and `events`, only the HTTP request is sent to the authorization plugins. The Engine's authorization middleware fails closed: when a plugin returns an error or returns `Allow: false`, the request is denied and the error is surfaced to the client. Plugins should also fail closed: if the plugin cannot confidently evaluate a request, it should return an error or `Allow: false`. > [!WARNING] > Because the plugin receives the [**raw** request body](#authzpluginauthzreq) from the daemon, it must > apply the same decoding semantics as the daemon to be sure it evaluates the request the daemon will > act on. The daemon decodes JSON with Go's [`encoding/json.Unmarshal`](https://pkg.go.dev/encoding/json#Unmarshal). > > The same requirement applies to the response body. Plugins that depend on `ResponseBody` > inspection for redaction or content-filtering should restrict their policies to endpoints > whose response is produced as a single write (typical of REST-style API responses). For > commands whose responses are streamed or are likely to exceed the [buffer](#response-body-size-and-partial-buffering) through multiple > writes, do not rely on `ResponseBody` for security-relevant decisions; perform the filtering > in a separate layer in front of the daemon. ### Response body size and partial buffering The internal buffer that holds the response body between the daemon's HTTP handler and the plugin's response authorization callback (`responseModifier`, defined in [`pkg/authorization/response.go`](https://github.com/moby/moby/blob/master/pkg/authorization/response.go)) has a fixed capacity of 64 KiB (`maxBufferSize`). For most non-streaming endpoints the full response is buffered for plugin inspection regardless of total size, because Go's `encoding/json` encoder serializes the complete payload into a single underlying write. The streaming-response exclusion noted above (for example, `logs` and `events`) is the practical effect of this 64 KiB threshold combined with the `io.WriteFlusher` write pattern used by streaming handlers, where each write is immediately drained to the client and is therefore no longer available for plugin inspection by the time the handler returns. During request/response processing, some authorization flows might need to do additional queries to the Docker daemon. To complete such flows, plugins can call the daemon API similar to a regular user. To enable these additional queries, the plugin must provide the means for an administrator to configure proper authentication and security policies. ## Docker client flows To enable and configure the authorization plugin, the plugin developer must support the Docker client interactions detailed in this section. ### Setting up Docker daemon Enable the authorization plugin with a dedicated command line flag in the `--authorization-plugin=PLUGIN_ID` format. The flag supplies a `PLUGIN_ID` value. This value can be the plugin’s socket or a path to a specification file. Authorization plugins can be loaded without restarting the daemon. Refer to the [`dockerd` documentation](https://docs.docker.com/reference/cli/dockerd/#configuration-reload-behavior) for more information. ```console $ dockerd --authorization-plugin=plugin1 --authorization-plugin=plugin2,... ``` Docker's authorization subsystem supports multiple `--authorization-plugin` parameters. ### Calling authorized command (allow) ```console $ docker pull centos <...> f1b10cd84249: Pull complete <...> ``` ### Calling unauthorized command (deny) ```console $ docker pull centos <...> docker: Error response from daemon: authorization denied by plugin PLUGIN_NAME: volumes are not allowed. ``` ### Error from plugins ```console $ docker pull centos <...> docker: Error response from daemon: plugin PLUGIN_NAME failed with error: AuthZPlugin.AuthZReq: Cannot connect to the Docker daemon. Is the docker daemon running on this host?. ``` ## API schema and implementation In addition to Docker's standard plugin registration method, each plugin should implement the following two methods: * `/AuthZPlugin.AuthZReq` This authorize request method is called before the Docker daemon processes the client request. * `/AuthZPlugin.AuthZRes` This authorize response method is called before the response is returned from Docker daemon to the client. #### /AuthZPlugin.AuthZReq Request ```json { "User": "The user identification", "UserAuthNMethod": "The authentication method used", "RequestMethod": "The HTTP method", "RequestURI": "The HTTP request URI", "RequestBody": "Byte array containing the raw HTTP request body", "RequestHeader": "Byte array containing the raw HTTP request header as a map[string][]string " } ``` Response ```json { "Allow": "Determined whether the user is allowed or not", "Msg": "The authorization message", "Err": "The error message if things go wrong" } ``` #### /AuthZPlugin.AuthZRes Request: ```json { "User": "The user identification", "UserAuthNMethod": "The authentication method used", "RequestMethod": "The HTTP method", "RequestURI": "The HTTP request URI", "RequestBody": "Byte array containing the raw HTTP request body", "RequestHeader": "Byte array containing the raw HTTP request header as a map[string][]string", "ResponseBody": "Byte array containing the raw HTTP response body", "ResponseHeader": "Byte array containing the raw HTTP response header as a map[string][]string", "ResponseStatusCode":"Response status code" } ``` Response: ```json { "Allow": "Determined whether the user is allowed or not", "Msg": "The authorization message", "Err": "The error message if things go wrong" } ``` ### Request authorization Each plugin must support two request authorization messages formats, one from the daemon to the plugin and then from the plugin to the daemon. The tables below detail the content expected in each message. #### Daemon -> Plugin Name | Type | Description -----------------------|-------------------|------------------------------------------------------- User | string | The user identification Authentication method | string | The authentication method used Request method | enum | The HTTP method (GET/DELETE/POST) Request URI | string | The HTTP request URI including API version, as sent by the client (e.g., v.1.17/containers/json) Request headers | map[string]string | Request headers as key value pairs (without the authorization header) Request body | []byte | Raw request body #### Plugin -> Daemon Name | Type | Description --------|--------|---------------------------------------------------------------------------------- Allow | bool | Boolean value indicating whether the request is allowed or denied Msg | string | Authorization message (will be returned to the client in case the access is denied) Err | string | Error message (will be returned to the client in case the plugin encounter an error. The string value supplied may appear in logs, so should not include confidential information) ### Response authorization The plugin must support two authorization messages formats, one from the daemon to the plugin and then from the plugin to the daemon. The tables below detail the content expected in each message. #### Daemon -> Plugin Name | Type | Description ----------------------- |------------------ |---------------------------------------------------- User | string | The user identification Authentication method | string | The authentication method used Request method | string | The HTTP method (GET/DELETE/POST) Request URI | string | The HTTP request URI including API version, as sent by the client (e.g., v.1.17/containers/json) Request headers | map[string]string | Request headers as key value pairs (without the authorization header) Request body | []byte | Raw request body Response status code | int | Status code from the Docker daemon Response headers | map[string]string | Response headers as key value pairs Response body | []byte | Raw Docker daemon response body #### Plugin -> Daemon Name | Type | Description --------|--------|---------------------------------------------------------------------------------- Allow | bool | Boolean value indicating whether the response is allowed or denied Msg | string | Authorization message (will be returned to the client in case the access is denied) Err | string | Error message (will be returned to the client in case the plugin encounter an error. The string value supplied may appear in logs, so should not include confidential information) --- ## File: docs/extend/plugins_logging.md --- title: Docker log driver plugins keywords: "Examples, Usage, plugins, docker, documentation, user guide, logging" --- This document describes logging driver plugins for Docker. Logging drivers enables users to forward container logs to another service for processing. Docker includes several logging drivers as built-ins, however can never hope to support all use-cases with built-in drivers. Plugins allow Docker to support a wide range of logging services without requiring to embed client libraries for these services in the main Docker codebase. See the [plugin documentation](legacy_plugins.md) for more information. ## Create a logging plugin The main interface for logging plugins uses the same JSON+HTTP RPC protocol used by other plugin types. See the [example](https://github.com/cpuguy83/docker-log-driver-test) plugin for a reference implementation of a logging plugin. The example wraps the built-in `jsonfilelog` log driver. ## LogDriver protocol Logging plugins must register as a `LogDriver` during plugin activation. Once activated users can specify the plugin as a log driver. There are two HTTP endpoints that logging plugins must implement: ### `/LogDriver.StartLogging` Signals to the plugin that a container is starting that the plugin should start receiving logs for. Logs will be streamed over the defined file in the request. On Linux this file is a FIFO. Logging plugins are not currently supported on Windows. Request: ```json { "File": "/path/to/file/stream", "Info": { "ContainerID": "123456" } } ``` `File` is the path to the log stream that needs to be consumed. Each call to `StartLogging` should provide a different file path, even if it's a container that the plugin has already received logs for prior. The file is created by Docker with a randomly generated name. `Info` is details about the container that's being logged. This is fairly free-form, but is defined by the following struct definition: ```go type Info struct { Config map[string]string ContainerID string ContainerName string ContainerEntrypoint string ContainerArgs []string ContainerImageID string ContainerImageName string ContainerCreated time.Time ContainerEnv []string ContainerLabels map[string]string LogPath string DaemonName string } ``` `ContainerID` will always be supplied with this struct, but other fields may be empty or missing. Response: ```json { "Err": "" } ``` If an error occurred during this request, add an error message to the `Err` field in the response. If no error then you can either send an empty response (`{}`) or an empty value for the `Err` field. The driver should at this point be consuming log messages from the passed in file. If messages are unconsumed, it may cause the container to block while trying to write to its stdio streams. Log stream messages are encoded as protocol buffers. The protobuf definitions are in the [moby repository](https://github.com/moby/moby/blob/master/api/types/plugins/logdriver/entry.proto). Since protocol buffers are not self-delimited you must decode them from the stream using the following stream format: ```text [size][message] ``` Where `size` is a 4-byte big endian binary encoded uint32. `size` in this case defines the size of the next message. `message` is the actual log entry. A reference golang implementation of a stream encoder/decoder can be found [here](https://github.com/docker/docker/blob/master/api/types/plugins/logdriver/io.go) ### `/LogDriver.StopLogging` Signals to the plugin to stop collecting logs from the defined file. Once a response is received, the file will be removed by Docker. You must make sure to collect all logs on the stream before responding to this request or risk losing log data. Requests on this endpoint does not mean that the container has been removed only that it has stopped. Request: ```json { "File": "/path/to/file/stream" } ``` Response: ```json { "Err": "" } ``` If an error occurred during this request, add an error message to the `Err` field in the response. If no error then you can either send an empty response (`{}`) or an empty value for the `Err` field. ## Optional endpoints Logging plugins can implement two extra logging endpoints: ### `/LogDriver.Capabilities` Defines the capabilities of the log driver. You must implement this endpoint for Docker to be able to take advantage of any of the defined capabilities. Request: ```json {} ``` Response: ```json { "ReadLogs": true } ``` Supported capabilities: - `ReadLogs` - this tells Docker that the plugin is capable of reading back logs to clients. Plugins that report that they support `ReadLogs` must implement the `/LogDriver.ReadLogs` endpoint ### `/LogDriver.ReadLogs` Reads back logs to the client. This is used when `docker logs ` is called. In order for Docker to use this endpoint, the plugin must specify as much when `/LogDriver.Capabilities` is called. Request: ```json { "ReadConfig": {}, "Info": { "ContainerID": "123456" } } ``` `ReadConfig` is the list of options for reading, it is defined with the following golang struct: ```go type ReadConfig struct { Since time.Time Tail int Follow bool } ``` - `Since` defines the oldest log that should be sent. - `Tail` defines the number of lines to read (e.g. like the command `tail -n 10`) - `Follow` signals that the client wants to stay attached to receive new log messages as they come in once the existing logs have been read. `Info` is the same type defined in `/LogDriver.StartLogging`. It should be used to determine what set of logs to read. Response: ```text {{ log stream }} ``` The response should be the encoded log message using the same format as the messages that the plugin consumed from Docker. --- ## File: docs/extend/plugins_metrics.md --- title: Docker metrics collector plugins keywords: "Examples, Usage, plugins, docker, documentation, user guide, metrics" --- Docker exposes internal metrics based on the Prometheus format. Metrics plugins enable accessing these metrics in a consistent way by providing a Unix socket at a predefined path where the plugin can scrape the metrics. > [!NOTE] > While the plugin interface for metrics is non-experimental, the naming of the > metrics and metric labels is still considered experimental and may change in a > future version. ## Creating a metrics plugin You must currently set `PropagatedMount` in the plugin `config.json` to `/run/docker`. This allows the plugin to receive updated mounts (the bind-mounted socket) from Docker after the plugin is already configured. ## MetricsCollector protocol Metrics plugins must register as implementing the`MetricsCollector` interface in `config.json`. On Unix platforms, the socket is located at `/run/docker/metrics.sock` in the plugin's rootfs. `MetricsCollector` must implement two endpoints: ### `MetricsCollector.StartMetrics` Signals to the plugin that the metrics socket is now available for scraping Request: ```json {} ``` The request has no payload. Response: ```json { "Err": "" } ``` If an error occurred during this request, add an error message to the `Err` field in the response. If no error then you can either send an empty response (`{}`) or an empty value for the `Err` field. Errors will only be logged. ### `MetricsCollector.StopMetrics` Signals to the plugin that the metrics socket is no longer available. This may happen when the daemon is shutting down. Request: ```json {} ``` The request has no payload. Response: ```json { "Err": "" } ``` If an error occurred during this request, add an error message to the `Err` field in the response. If no error then you can either send an empty response (`{}`) or an empty value for the `Err` field. Errors will only be logged. --- ## File: docs/extend/plugins_network.md --- title: Docker network driver plugins keywords: "Examples, Usage, plugins, docker, documentation, user guide" --- This document describes Docker Engine network driver plugins generally available in Docker Engine. To view information on plugins managed by Docker Engine, refer to [Docker Engine plugin system](_index.md). Docker Engine network plugins enable Engine deployments to be extended to support a wide range of networking technologies, such as VXLAN, IPVLAN, MACVLAN or something completely different. Network driver plugins are supported via the LibNetwork project. Each plugin is implemented as a "remote driver" for LibNetwork, which shares plugin infrastructure with Engine. Effectively, network driver plugins are activated in the same way as other plugins, and use the same kind of protocol. ## Network plugins and Swarm mode [Legacy plugins](legacy_plugins.md) do not work in Swarm mode. However, plugins written using the [v2 plugin system](_index.md) do work in Swarm mode, as long as they are installed on each Swarm worker node. ## Use network driver plugins The means of installing and running a network driver plugin depend on the particular plugin. So, be sure to install your plugin according to the instructions obtained from the plugin developer. Once running however, network driver plugins are used just like the built-in network drivers: by being mentioned as a driver in network-oriented Docker commands. For example, ```console $ docker network create --driver weave mynet ``` Some network driver plugins are listed in [plugins](legacy_plugins.md) The `mynet` network is now owned by `weave`, so subsequent commands referring to that network will be sent to the plugin, ```console $ docker run --network=mynet busybox top ``` ## Find network plugins Network plugins are written by third parties, and are published by those third parties, either on [Docker Hub](https://hub.docker.com/search?q=&type=plugin) or on the third party's site. ## Write a network plugin Network plugins implement the [Docker plugin API](plugin_api.md) and the network plugin protocol ## Network plugin protocol The network driver protocol, in addition to the plugin activation call, is documented as part of libnetwork: [https://github.com/moby/moby/blob/master/daemon/libnetwork/docs/remote.md](https://github.com/moby/moby/blob/master/daemon/libnetwork/docs/remote.md). ## 2. Official Technical Reference & Guides (docker/docs) # Docs @ Docker Welcome to the Docker Documentation repository. This is the source for the [Docker Docs Website](https://docs.docker.com/). Feel free to open pull requests or issues. Our docs are completely open source, and we deeply appreciate contributions from the Docker community! ## Provide feedback We’d love to hear your feedback! To submit feedback: - Click **[New issue](https://github.com/docker/docs/issues/new)** on the docs repository, or - Click **Request changes** in the right column of every page on [docs.docker.com](https://docs.docker.com/), or - Click **Give feedback** on every page in the docs. To get community support, use the [Docker Community Slack](https://dockr.ly/comm-slack). Personalized support is available through the Docker Pro, Team, and Business subscriptions. See [Docker Pricing](https://www.docker.com/pricing?ref=Docs&refAction=DocsReadme) for details. If you have an idea for a new feature or behavior change in a specific aspect of Docker or have found a product bug, file an issue in the project's repository. ## Contribute to Docker docs We welcome contributions! To get started: - [CONTRIBUTING.md](CONTRIBUTING.md) - Contribution workflow and setup - [STYLE.md](STYLE.md) - Writing style and content guidelines - [COMPONENTS.md](COMPONENTS.md) - Component and shortcode usage ## Copyright and license Copyright 2013-2026 Docker, Inc., released under the [Apache 2.0 license](https://github.com/docker/docs/blob/main/LICENSE).