# Technical Documentation: GoogleCloudPlatform/golang-samples

> ℹ️ **Provenance:** Multi-Tier Ingestion · [CodeWiki Reference](https://codewiki.google/github.com/GoogleCloudPlatform/golang-samples)

### Overview (README.md)

# Google Cloud Platform Go Samples

This repository holds sample code written in Go that demonstrates the Google
Cloud Platform.

Some samples have accompanying guides on
[cloud.google.com](https://cloud.google.com). See respective README files for
details.

## Google Cloud Samples

To browse ready to use code samples check [Google Cloud Samples](https://cloud.google.com/docs/samples?l=go).

## Depending on samples

**Copy any code you need from this repository into your own project.**

Warning: Do not depend directly on the samples in this repo. Breaking changes
may be made at any time without warning.

## Contributing changes

Interested in contributing a new sample? Please open an issue describing the intended sample. Additionally, bug fixes are welcome, either as pull requests or as GitHub issues.

See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute.

## Licensing

Code in this repository is licensed under the Apache 2.0. See [LICENSE](LICENSE).

---

### Appengine Backends Index (`docs/appengine/backends/index.txt`)

// NOTE: Backends are deprecated. The google.golang.org/appengine package does not support backends.

// [START shutdown]
func init() {
    http.HandleFunc("/_ah/stop", shutdownHandler)
}

func shutdownHandler(w http.ResponseWriter, r *http.Request) {
    doSomeWork()
    saveState()
}
// [END shutdown]

// [START addressing_backends]
func handler(w http.ResponseWriter, r *http.Request) {
    ctx := appengine.NewContext(r)

    // Get the details of the current backend.
    name, index := appengine.BackendInstance(ctx)

    // Get the hostname of this specific backend.
    hostname := appengine.BackendHostname(ctx, name, index)

    fmt.Fprint(w, "I am backend %s instance %d ", name, index)
    fmt.Fprint(w, "serving http://%s", hostname)
}
// [END addressing_backends]

---

### Appengine Config Appconfig (`docs/appengine/config/appconfig.txt`)

// [START gae_golang_about_app_yaml_example]
runtime: go
api_version: go1

handlers:
- url: /stylesheets
  static_dir: stylesheets

- url: /(.*\.(gif|png|jpg))$
  static_files: static/\1
  upload: static/.*\.(gif|png|jpg)$

- url: /.*
  script: _go_app
// [END gae_golang_about_app_yaml_example]

// [START gae_golang_handlers_example]
handlers:
- url: /images
  static_dir: static/images

- url: /.*
  script: _go_app
// [END gae_golang_handlers_example]

// [START gae_golang_script_example]
handlers:

# The root URL (/) is handled by the Go application.
# No other URLs match this pattern.
- url: /
  script: _go_app

# The URL /index.html is also handled by the Go application.
- url: /index\.html
  script: _go_app

# A regular expression indicating that it should be handled
# by the Go application.
- url: /browse/(books|videos|tools)
  script: _go_app

# All other URLs are handled by the Go application.
- url: /.*
  script: _go_app
// [END gae_golang_script_example]

// [START gae_golang_login_example]
handlers:

- url: /profile/.*
  script: _go_app
  login: required

- url: /admin/.*
  script: _go_app
  login: admin

- url: /.*
  script: _go_app
// [END gae_golang_login_example]

//[START gae_golang_auth_fail_action_example]
handlers:
- url: /secure_api/.*
  script: _go_app
  login: required
  auth_fail_action: unauthorized
//[END gae_golang_auth_fail_action_example]

//[START gae_golang_expiration_example]
runtime: go
api_version: go1

default_expiration: "4d 5h"

handlers:
  # ...
//[END gae_golang_expiration_example]

//[START gae_golang_secure_urls]
handlers:
- url: /youraccount/.*
  script: _go_app
  login: required
  secure: always
//[END gae_golang_secure_urls]

//[START gae_golang_inbound_services]
inbound_services:
- warmup
//[END gae_golang_inbound_services]

//[START gae_golang_os_getenv_example]
import "os"
//...
if v := os.Getenv("MY_VAR"); v != "" {
  //...
}
//[END gae_golang_os_getenv_example]

//[START gae_golang_redirect_http_response_code]
handlers:
- url: /youraccount/.*
  script: _go_app
  login: required
  secure: always
  redirect_http_response_code: 301
//[END gae_golang_redirect_http_response_code]

---

### Appengine Config Cron (`docs/appengine/config/cron.txt`)

// [START securing_URLs_for_cron]
runtime: go
api_version: go1

handlers:
- url: /report/weekly
  script: _go_app
  login: admin
// [END securing_URLs_for_cron]

---

### Appengine Googlecloudstorageclient Download (`docs/appengine/googlecloudstorageclient/download.txt`)

// [START GOPATH_setup]
mkdir -p $HOME/go
export GOPATH=$HOME/go
// [END GOPATH_setup]
// [START Go_install]
go get -u golang.org/x/oauth2
go get -u cloud.google.com/go/storage
go get -u google.golang.org/appengine/...
// [END Go_install]

---

### Appengine Googlecloudstorageclient Getstarted (`docs/appengine/googlecloudstorageclient/getstarted.txt`)

// [START App_Engine_Example]
/path/to/AppEngSDK/dev_appserver.py . --appidentity_email_address <your_app_email_address>@developer.gserviceaccount.com --appidentity_private_key_path pem_file.pem
// [END App_Engine_Example]
// [START Managed_VM_Example]
/path/to/CloudSDK/gcloud app run ./app.yaml --appidentity-email-address <your_app_email_address>@developer.gserviceaccount.com --appidentity-private-key-path pem_file.pem
// [END Managed_VM_Example]

---

### Appengine Logs Index (`docs/appengine/logs/index.txt`)

// [START the_development_server_and_Logs_API_1]
dev_appserver.py --persist_logs your-app-directory
// [END the_development_server_and_Logs_API_1]

// [START the_development_server_and_Logs_API_2]
dev_appserver.py --logs_path=your-path/your-logfile-name your-app-directory
// [END the_development_server_and_Logs_API_2]

---

### Appengine Modules Converting (`docs/appengine/modules/converting.txt`)

// [START sample_1]
backends:
- name: memdb
  class: B8
  instances: 5
- name: worker
  start: _go_app
  options: failfast
- name: cmdline
  options: dynamic
// [END sample_1]

// [START sample_2]
service: memdb
instance_class: B8
manual_scaling:
  instances: 5
// [END sample_2]

// [START sample_3]
service: worker
# For failfast functionality, please use the ‘X-AppEngine-FailFast’ header on requests made to this service.
manual_scaling:
  instances: 1
handlers:
# If a service has an /_ah/start handler, it should be listed first.
- url: /_ah/start
  script: _go_app
// [END sample_3]

// [START sample_4]
service: cmdline
basic_scaling:
  max_instances: 1
// [END sample_4]

// [START sample_5]
$ path-to-sdk/backends_conversion.py backends.yaml app.yaml
// [END sample_5]

---

### Appengine Modules Index (`docs/appengine/modules/index.txt`)

// [START manual_scaling]
service: my_service
runtime: go
api_version: go1
instance_class: B8
manual_scaling:
  instances: 5
// [END manual_scaling]

// [START basic_scaling]
service: my_service
runtime: go
api_version: go1
instance_class: B8
basic_scaling:
  max_instances: 11
  idle_timeout: 10m
// [END basic_scaling]

// [START automatic_scaling]
service: my_service
runtime: go
api_version: go1
instance_class: F2
automatic_scaling:
  min_idle_instances: 5
  max_idle_instances: automatic  # default value
  min_pending_latency: 30ms  # default value
  max_pending_latency: automatic
  max_concurrent_requests: 50
// [END automatic_scaling]

// [START example_1]
runtime: go
api_version: go1
// [END example_1]

// [START example_2]
service: mobile-frontend
runtime: go
api_version: go1

automatic_scaling:
  min_idle_instances: 2
  max_pending_latency: 1s
// [END example_2]

// [START example_3]
service: my_service
runtime: go
api_version: go1

instance_class: B8
manual_scaling:
  instances: 1
// [END example_3]

---

### Appengine Modules Routing (`docs/appengine/modules/routing.txt`)

// [START sample_1]
dispatch:
  # Default service serves the typical web resources and all static resources.
  - url: "*/favicon.ico"
    service: default

  # Default service serves simple hostname request.
  - url: "simple-sample.appspot.com/"
    service: default

  # Send all mobile traffic to the mobile frontend.
  - url: "*/mobile/*"
    service: mobile-frontend

  # Send all work to the one static backend.
  - url: "*/work/*"
    service: static-backend
// [END sample_1]

// [START sample_2]
# Send any path that begins with “simple-sample.appspot.com/mobile” to the mobile-frontend service.
- url: "simple-sample.appspot.com/mobile*"
  service: mobile-frontend

# Send any domain/sub-domain with a path that starts with “work” to the static backend service.
- url: "*/work*"
  service: static-backend
// [END sample_2]

// [START sample_3]
# Matches the path "/fun", but not "/fun2" or "/fun/other".
- url: "*/fun"
  service: mobile-frontend

# Matches the hostname "customer1.myapp.com", but not "1.customer1.myapp.com".
- url: "customer1.myapp.com/*"
  service: static-backend
// [END sample_3]

---

### Appengine Tools Uploadingdata (`docs/appengine/tools/uploadingdata.txt`)

// [START setting_up_remote_api_1]
- url: /_ah/remote_api
  script: _go_app
// [END setting_up_remote_api_1]

// [START setting_up_remote_api_2]
import _ "google.golang.org/appengine/remote_api"
// [END setting_up_remote_api_2]

// [START setting_up_remote_api_3]
gcloud app deploy app.yaml
// [END setting_up_remote_api_3]

---

### Appengine Datastore Indexes Queries (`docs/appengine/datastore/indexes/queries.txt`)

// [START queries_and_indexes_example_1]
SELECT * FROM Person WHERE LastName = "Smith"
                       AND Height < 72
                  ORDER BY Height DESC
// [END queries_and_indexes_example_1]

// [START queries_and_indexes_example_2]
SELECT * FROM Person WHERE LastName = "Jones"
                       AND Height < 63
                     ORDER BY Height DESC
// [END queries_and_indexes_example_2]

// [START queries_and_indexes_example_3]
SELECT * FROM Person WHERE LastName = "Friedkin"
                       AND FirstName = "Damian"
                     ORDER BY Height ASC
// [END queries_and_indexes_example_3]

// [START queries_and_indexes_example_4]
SELECT * FROM Person WHERE LastName = "Blair"
                  ORDER BY FirstName, Height ASC
// [END queries_and_indexes_example_4]

// [START exploding_index_example_1]
SELECT * FROM Widget WHERE X=1 AND Y=2 ORDER BY Date
// [END exploding_index_example_1]

---

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- Canonical Reference: https://codewiki.google/github.com/GoogleCloudPlatform/golang-samples