Categorygoogle.golang.org/appengine
modulepackage
2.0.6+incompatible
Repository: https://github.com/golang/appengine.git
Documentation: pkg.go.dev
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# README

Go App Engine packages

CI Status

This repository supports the Go runtime on App Engine standard. It provides APIs for interacting with App Engine services. Its canonical import path is google.golang.org/appengine.

See https://cloud.google.com/appengine/docs/go/ for more information.

File issue reports and feature requests on the GitHub's issue tracker.

Upgrading an App Engine app to the flexible environment

This package does not work on App Engine flexible.

There are many differences between the App Engine standard environment and the flexible environment.

See the documentation on upgrading to the flexible environment.

Directory structure

The top level directory of this repository is the appengine package. It contains the basic APIs (e.g. appengine.NewContext) that apply across APIs. Specific API packages are in subdirectories (e.g. datastore).

There is an internal subdirectory that contains service protocol buffers, plus packages required for connectivity to make API calls. App Engine apps should not directly import any package under internal.

Updating from legacy (import "appengine") packages

If you're currently using the bare appengine packages (that is, not these ones, imported via google.golang.org/appengine), then you can use the aefix tool to help automate an upgrade to these packages.

Run go get google.golang.org/appengine/cmd/aefix to install it.

1. Update import paths

The import paths for App Engine packages are now fully qualified, based at google.golang.org/appengine. You will need to update your code to use import paths starting with that; for instance, code importing appengine/datastore will now need to import google.golang.org/appengine/datastore.

2. Update code using deprecated, removed or modified APIs

Most App Engine services are available with exactly the same API. A few APIs were cleaned up, and there are some differences:

  • appengine.Context has been replaced with the Context type from context.
  • Logging methods that were on appengine.Context are now functions in google.golang.org/appengine/log.
  • appengine.Timeout has been removed. Use context.WithTimeout instead.
  • appengine.Datacenter now takes a context.Context argument.
  • datastore.PropertyLoadSaver has been simplified to use slices in place of channels.
  • delay.Call now returns an error.
  • search.FieldLoadSaver now handles document metadata.
  • urlfetch.Transport no longer has a Deadline field; set a deadline on the context.Context instead.
  • aetest no longer declares its own Context type, and uses the standard one instead.
  • taskqueue.QueueStats no longer takes a maxTasks argument. That argument has been deprecated and unused for a long time.
  • appengine.BackendHostname and appengine.BackendInstance were for the deprecated backends feature. Use appengine.ModuleHostnameand appengine.ModuleName instead.
  • Most of appengine/file and parts of appengine/blobstore are deprecated. Use Google Cloud Storage if the feature you require is not present in the new blobstore package.
  • appengine/socket is not required on App Engine flexible environment / Managed VMs. Use the standard net package instead.

Key Encode/Decode compatibility to help with datastore library migrations

Key compatibility updates have been added to help customers transition from google.golang.org/appengine/datastore to cloud.google.com/go/datastore. The EnableKeyConversion enables automatic conversion from a key encoded with cloud.google.com/go/datastore to google.golang.org/appengine/datastore key type.

Enabling key conversion

Enable key conversion by calling EnableKeyConversion(ctx) in the /_ah/start handler for basic and manual scaling or any handler in automatic scaling.

1. Basic or manual scaling

This start handler will enable key conversion for all handlers in the service.

http.HandleFunc("/_ah/start", func(w http.ResponseWriter, r *http.Request) {
    datastore.EnableKeyConversion(appengine.NewContext(r))
})

2. Automatic scaling

/_ah/start is not supported for automatic scaling and /_ah/warmup is not guaranteed to run, so you must call datastore.EnableKeyConversion(appengine.NewContext(r)) before you use code that needs key conversion.

You may want to add this to each of your handlers, or introduce middleware where it's called. EnableKeyConversion is safe for concurrent use. Any call to it after the first is ignored.

# Packages

Package aetest provides an API for running dev_appserver for use in tests.
Package blobstore provides a client for App Engine's persistent blob storage service.
Package capability exposes information about outages and scheduled downtime for specific API capabilities.
Package channel implements the server side of App Engine's Channel API.
Package cloudsql exposes access to Google Cloud SQL databases.
No description provided by the author
Package datastore provides a client for App Engine's datastore service.
Package delay provides a way to execute code outside the scope of a user request by using the taskqueue API.
No description provided by the author
Package file provides helper functions for using Google Cloud Storage.
Package image provides image services.
Package log provides the means of writing and querying an application's logs from within an App Engine application.
Package mail provides the means of sending email from an App Engine application.
Package memcache provides a client for App Engine's distributed in-memory key-value store for small chunks of arbitrary data.
Package module provides functions for interacting with modules.
Package remote_api implements the /_ah/remote_api endpoint.
Package runtime exposes information about the resource usage of the application.
Package search provides a client for App Engine's search service.
Package socket provides outbound network sockets.
Package taskqueue provides a client for App Engine's taskqueue service.
Package urlfetch provides an http.RoundTripper implementation for fetching URLs via App Engine's urlfetch service.
Package user provides a client for App Engine's user authentication service.
Package xmpp provides the means to send and receive instant messages to and from users of XMPP-compatible services.

# Functions

AccessToken generates an OAuth2 access token for the specified scopes on behalf of service account of this application.
APICall performs an API call.
AppID returns the application ID for the current application.
BackgroundContext returns a context not associated with a request.
Datacenter returns an identifier for the datacenter that the instance is running in.
DefaultVersionHostname returns the standard hostname of the default version of the current application (e.g.
InstanceID returns a mostly-unique identifier for this instance.
IsAppEngine reports whether the App Engine app is running on App Engine, in either the standard or flexible environment.
IsDevAppServer reports whether the App Engine app is running in the development App Server.
IsFlex reports whether the App Engine app is running in the flexible environment.
IsOverQuota reports whether err represents an API call failure due to insufficient available quota.
IsSecondGen reports whether the App Engine app is running on the second generation runtimes (>= Go 1.11).
IsStandard reports whether the App Engine app is running in the standard environment.
IsTimeoutError reports whether err is a timeout error.
Main is the principal entry point for an app running in App Engine.
ModuleHostname returns a hostname of a module instance.
ModuleName returns the module name of the current instance.
Namespace returns a replacement context that operates within the given namespace.
NewContext returns a context for an in-flight HTTP request.
PublicCertificates retrieves the public certificates for the app.
RequestID returns a string that uniquely identifies the request.
ServerSoftware returns the App Engine release version.
ServiceAccount returns a string representing the service account name, in the form of an email address (typically [email protected]).
SignBytes signs bytes using a private key unique to your application.
VersionID returns the version ID for the current application.
WithAPICallFunc returns a copy of the parent context that will cause API calls to invoke f instead of their normal operation.
WithContext returns a copy of the parent context and associates it with an in-flight HTTP request.

# Variables

Middleware wraps an http handler so that it can make GAE API calls.

# Structs

Certificate represents a public certificate for the app.
GeoPoint represents a location as latitude/longitude in degrees.

# Type aliases

APICallFunc defines a function type for handling an API call.
BlobKey is a key for a blobstore blob.
MultiError is returned by batch operations when there are errors with particular elements.