operator-sdk Documentation

File: README.md Copy Chapter

⚠️ IMPORTANT NOTICE: Images under gcr.io/kubebuilder/ Will Be Unavailable Soon

If your project uses gcr.io/kubebuilder/kube-rbac-proxy it will be affected.
Your project may fail to work if the image cannot be pulled. You must move as soon as possible, sometime from early 2025, the GCR will go away.

The usage of the project kube-rbac-proxy was discontinued from Kubebuilder and Operator-SDK.
It was replaced for similar protection using authn/authz via Controller-Runtime's feature WithAuthenticationAndAuthorization.

For more information and guidance see the discussion https://github.com/kubernetes-sigs/kubebuilder/discussions/3907

Documentation Copy Chapter

Docs can be found on the Operator SDK website.

Overview Copy Chapter

This project is a component of the Operator Framework, an
open source toolkit to manage Kubernetes native applications, called
Operators, in an effective, automated, and scalable way. Read more in
the introduction blog post.

Operators make it easy to manage complex stateful
applications on top of Kubernetes. However writing an Operator today can
be difficult because of challenges such as using low level APIs, writing
boilerplate, and a lack of modularity which leads to duplication.

The Operator SDK is a framework that uses the
controller-runtime library to make writing
operators easier by providing:

• High level APIs and abstractions to write the operational logic more intuitively
• Tools for scaffolding and code generation to bootstrap a new project fast
• Extensions to cover common Operator use cases

Dependency and platform support Copy Chapter

Go version Copy Section

Release binaries will be built with the Go compiler version specified in the developer guide.
A Go Operator project's Go version can be found in its go.mod file.

Kubernetes versions Copy Section

Supported Kubernetes versions for your Operator project or relevant binary can be determined
by following this compatibility guide.

Platforms Copy Section

The set of supported platforms for all binaries and images can be found in these tables.

Community and how to get involved Copy Chapter

• Operator framework community
• Communication channels
• Project meetings

How to contribute Copy Chapter

Check out the contributor documentation.

License Copy Chapter

Operator SDK is under Apache 2.0 license. See the LICENSE file for details.

File: proposals/README.md Copy Chapter

Operator SDK Proposals

This directory contains design documents for accepted proposals. To
propose a new feature use the template document. Note that
if the proposal gets accepted whoever is the proposal implementation
owner is expected to carry out the implementation, the implementation
owner can be different to the proposal creator.

File: testdata/helm/memcached-operator/helm-charts/memcached/README.md Copy Chapter

Memcached

Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

Based on the memcached chart from the Bitnami Charts repository.

TL;DR; Copy Chapter

$ helm install stable/memcached

Introduction Copy Chapter

This chart bootstraps a Memcached deployment on a Kubernetes cluster using the Helm package manager.

Installing the Chart Copy Chapter

To install the chart with the release name my-release:

$ helm install --name my-release stable/memcached

The command deploys Memcached on the Kubernetes cluster in the default configuration. The configuration section lists the parameters that can be configured during installation.

Tip: List all releases using helm list

Uninstalling the Chart Copy Chapter

To uninstall/delete the my-release deployment:

$ helm delete my-release

The command removes all the Kubernetes components associated with the chart and deletes the release.

Configuration Copy Chapter

The following table lists the configurable parameters of the Memcached chart and their default values.

The above parameters map to memcached params. For more information please refer to the Memcached documentation.

Specify each parameter using the --set key=value[,key=value] argument to helm install. For example,

$ helm install --name my-release \
  --set memcached.verbosity=v \
    stable/memcached

The above command sets the Memcached verbosity to v.

Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,

$ helm install --name my-release -f values.yaml stable/memcached

Tip: You can use the default values.yaml

Upgrading to 3.x from a previous major version Copy Chapter

Version 3.0.0 of this chart makes an incompatible change to the way StatefulSet/Deployment selectors are configured. If you try to upgrade from a previous major version, you will see an error like this:

Error: UPGRADE FAILED: Deployment.apps "mc-test-memcached" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app":"mc-test-memcached", "chart":"memcached-3.0.0", "custom":"value", "heritage":"Tiller", "release":"mc-test"}: `selector` does not match template `labels`

To upgrade from a previous major version, you'll either need to perform a small manual fix or delete and reinstall the chart.

Upgrading with `kind: StatefulSet` Copy Section

If you're using a StatefulSet, you'll have to manually delete it and allow Helm to re-create it. Run kubectl delete --cascade=false sts name-goes-here to delete the StatefulSet without deleting the pods. Once you've done this, upgrade the chart as normal, and the newly-created StatefulSet will adopt the old pods.

Upgrading with `kind: Deployment` Copy Section

If you're using a Deployment, the manual fix is to remove all selectors from the spec except app and release. Run kubectl edit deploy name-goes-here, and you should see a part like this in your editor about 20 lines down:

spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 2
  selector:
    matchLabels:
      app: mc-test-memcached
      chart: memcached-2.10.2
      heritage: Tiller
      release: mc-test

Remove the lines under matchLabels except app: ... and release: ..., and don't change any other lines. The part from above should look like this when you're done:

spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 2
  selector:
    matchLabels:
      app: mc-test-memcached
      release: mc-test

Once you've done this, you can upgrade to 3.x with Helm as normal.

If you want prometheus-operator scrap all serviceMonitors in your cluster you need to set:

prometheus:
  prometheusSpec:
    serviceMonitorSelectorNilUsesHelmValues: false

If you want to be specific:

prometheus:
  prometheusSpec:
    serviceMonitorSelector:
      matchLabels:
        app: memcached

You can have more intel in prometheus-operator values and here github

File: testdata/go/v4/monitoring/memcached-operator/docs/monitoring/runbooks/memcachedDeploymentSizeUndesired.md Copy Chapter

MemcachedDeploymentSizeUndesired

Meaning Copy Chapter

MemcachedDeploymentSizeUndesired is triggered when the number of available
memcached-sample replicas doesn't match the requested configuration.

Impact Copy Chapter

Unavailability of distributed memory object caching system in the cluster.

Diagnosis Copy Chapter

• Check memcached-sample's pod namespace:

  export NAMESPACE="$(kubectl get deployment -A | grep memcached-sample | awk '{print $1}')"

• Observe the status of the memcached-sample deployment:

  kubectl get deploy memcached-sample -n $NAMESPACE -o yaml

• Observe the logs of the memcached manager pod, to see why it cannot create the memcached-sample pods.

  kubectl get logs <memcached-operator-controller-manager-pod> -n memcached-operator-system

Mitigation Copy Chapter

There can be several reasons. Like:

• Node resource exhaustion
• Not enough memory on the cluster
• Nodes are down

Try to identify the root cause and fix it.

File: testdata/go/v4/monitoring/memcached-operator/docs/monitoring/runbooks/memcachedOperatorDown.md Copy Chapter

MemcachedOperatorDown

Meaning Copy Chapter

No running memcached-operator-controller-manager pods were detected in the last 5 min.

Impact Copy Chapter

Complete failure in the Memcached CR lifecycle management.
i.e. launching a new Memcached instance or shutting down an existing one.

Diagnosis Copy Chapter

• Observe the status of the memcached-operator-controller-manager deployment:

  kubectl get deploy memcached-operator-controller-manager -n mecmached-operator-system -o yaml

Mitigation Copy Chapter

There can be several reasons for the memcached-operator-controller-manager pod to be down, identify the root cause and fix it.

• Check the status of the memcached-operator-controller-manager deployment to
  find out more information. The following command will provide the associated events and show if there are any issues with pulling an image, crashing pod, etc.

kubectl describe deploy memcached-operator-controller-manager -n memcached-operator-system

• Check if there are issues with the nodes. For example, if they are in a NotReady state.

  kubectl get nodes

File: testdata/go/v4/monitoring/memcached-operator/docs/monitoring/metrics.md Copy Chapter

Operator Metrics

This document aims to help users that are not familiar with metrics exposed by this operator.
The metrics documentation is auto-generated by the utility tool "monitoring/metricsdocs" and reflects all of the metrics that are exposed by the operator.

Operator Metrics List Copy Chapter

memcached_deployment_size_undesired_count_total Copy Section

Total number of times the deployment size was not as desired. Type: Counter.

Developing new metrics Copy Chapter

After developing new metrics or changing old ones, please run "make generate-metricsdocs" to regenerate this document.

If you feel that the new metric doesn't follow these rules, please change "monitoring/metricsdocs" according to your needs.

File: testdata/go/v4/monitoring/memcached-operator/README.md Copy Chapter

memcached-operator

// TODO(user): Add simple overview of use/purpose

Description Copy Chapter

// TODO(user): An in-depth paragraph about your project and overview of use

Getting Started Copy Chapter

Prerequisites Copy Section

• go version v1.24.0+
• docker version 17.03+.
• kubectl version v1.11.3+.
• Access to a Kubernetes v1.11.3+ cluster.

To Deploy on the cluster Copy Section

Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/memcached-operator:tag

NOTE: This image ought to be published in the personal registry you specified.
And it is required to have access to pull the image from the working environment.
Make sure you have the proper permission to the registry if the above commands don’t work.

Install the CRDs into the cluster:

make install

Deploy the Manager to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/memcached-operator:tag

NOTE: If you encounter RBAC errors, you may need to grant yourself cluster-admin
privileges or be logged in as admin.

Create instances of your solution
You can apply the samples (examples) from the config/sample:

kubectl apply -k config/samples/

NOTE: Ensure that the samples has default values to test it out.

To Uninstall Copy Section

Delete the instances (CRs) from the cluster:

kubectl delete -k config/samples/

Delete the APIs(CRDs) from the cluster:

make uninstall

UnDeploy the controller from the cluster:

make undeploy

Project Distribution Copy Chapter

Following the options to release and provide this solution to the users.

By providing a bundle with all YAML files Copy Section

1. Build the installer for the image built and published in the registry:

make build-installer IMG=<some-registry>/memcached-operator:tag

NOTE: The makefile target mentioned above generates an 'install.yaml'
file in the dist directory. This file contains all the resources built
with Kustomize, which are necessary to install this project without its
dependencies.

2. Using the installer

Users can just run 'kubectl apply -f ' to install
the project, i.e.:

kubectl apply -f https://raw.githubusercontent.com/<org>/memcached-operator/<tag or branch>/dist/install.yaml

By providing a Helm Chart Copy Section

1. Build the chart using the optional helm plugin

operator-sdk edit --plugins=helm/v1-alpha

2. See that a chart was generated under 'dist/chart', and users
   can obtain this solution from there.

NOTE: If you change the project, you need to update the Helm Chart
using the same command above to sync the latest changes. Furthermore,
if you create webhooks, you need to use the above command with
the '--force' flag and manually ensure that any custom configuration
previously added to 'dist/chart/values.yaml' or 'dist/chart/manager/manager.yaml'
is manually re-applied afterwards.

Contributing Copy Chapter

// TODO(user): Add detailed information on how you would like others to contribute to this project

NOTE: Run make help for more information on all potential make targets

More information can be found via the Kubebuilder Documentation

License Copy Chapter

Copyright 2026.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

File: testdata/go/v4/memcached-operator/README.md Copy Chapter

memcached-operator

// TODO(user): Add simple overview of use/purpose

Description Copy Chapter

// TODO(user): An in-depth paragraph about your project and overview of use

Getting Started Copy Chapter

Prerequisites Copy Section

• go version v1.24.0+
• docker version 17.03+.
• kubectl version v1.11.3+.
• Access to a Kubernetes v1.11.3+ cluster.

To Deploy on the cluster Copy Section

Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/memcached-operator:tag

NOTE: This image ought to be published in the personal registry you specified.
And it is required to have access to pull the image from the working environment.
Make sure you have the proper permission to the registry if the above commands don’t work.

Install the CRDs into the cluster:

make install

Deploy the Manager to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/memcached-operator:tag

NOTE: If you encounter RBAC errors, you may need to grant yourself cluster-admin
privileges or be logged in as admin.

Create instances of your solution
You can apply the samples (examples) from the config/sample:

kubectl apply -k config/samples/

NOTE: Ensure that the samples has default values to test it out.

To Uninstall Copy Section

Delete the instances (CRs) from the cluster:

kubectl delete -k config/samples/

Delete the APIs(CRDs) from the cluster:

make uninstall

UnDeploy the controller from the cluster:

make undeploy

Project Distribution Copy Chapter

Following the options to release and provide this solution to the users.

By providing a bundle with all YAML files Copy Section

1. Build the installer for the image built and published in the registry:

make build-installer IMG=<some-registry>/memcached-operator:tag

NOTE: The makefile target mentioned above generates an 'install.yaml'
file in the dist directory. This file contains all the resources built
with Kustomize, which are necessary to install this project without its
dependencies.

2. Using the installer

Users can just run 'kubectl apply -f ' to install
the project, i.e.:

kubectl apply -f https://raw.githubusercontent.com/<org>/memcached-operator/<tag or branch>/dist/install.yaml

By providing a Helm Chart Copy Section

1. Build the chart using the optional helm plugin

operator-sdk edit --plugins=helm/v1-alpha

2. See that a chart was generated under 'dist/chart', and users
   can obtain this solution from there.

NOTE: If you change the project, you need to update the Helm Chart
using the same command above to sync the latest changes. Furthermore,
if you create webhooks, you need to use the above command with
the '--force' flag and manually ensure that any custom configuration
previously added to 'dist/chart/values.yaml' or 'dist/chart/manager/manager.yaml'
is manually re-applied afterwards.

Contributing Copy Chapter

// TODO(user): Add detailed information on how you would like others to contribute to this project

NOTE: Run make help for more information on all potential make targets

More information can be found via the Kubebuilder Documentation

License Copy Chapter

Copyright 2026.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

File: website/content/en/docs/advanced-topics/_index.md Copy Chapter

title: "Advanced Topics" linkTitle: "Advanced Topics" weight: 9 date: 2021-10-05 Advanced Topics. Copy Chapter