Go App Engine packages
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 theContext
type fromgolang.org/x/net/context
.- Logging methods that were on
appengine.Context
are now functions ingoogle.golang.org/appengine/log
. appengine.Timeout
has been removed. Usecontext.WithTimeout
instead.appengine.Datacenter
now takes acontext.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 thecontext.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
andappengine.BackendInstance
were for the deprecated backends feature. Useappengine.ModuleHostname
andappengine.ModuleName
instead.- Most of
appengine/file
and parts ofappengine/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 standardnet
package instead.
Key Encode/Decode compatibiltiy 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/startup
handler for basic and manual scaling or any handler in automatic scaling.
1. Basic or manual scaling
This startup 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.