74 lines
3.6 KiB
Markdown
74 lines
3.6 KiB
Markdown
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# Go App Engine packages
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[](https://travis-ci.org/golang/appengine)
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This repository supports the Go runtime on App Engine,
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including both the standard App Engine and the
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"App Engine flexible environment" (formerly known as "Managed VMs").
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It provides APIs for interacting with App Engine services.
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Its canonical import path is `google.golang.org/appengine`.
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See https://cloud.google.com/appengine/docs/go/
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for more information.
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File issue reports and feature requests on the [Google App Engine issue
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tracker](https://code.google.com/p/googleappengine/issues/entry?template=Go%20defect).
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## Directory structure
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The top level directory of this repository is the `appengine` package. It
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contains the
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basic APIs (e.g. `appengine.NewContext`) that apply across APIs. Specific API
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packages are in subdirectories (e.g. `datastore`).
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There is an `internal` subdirectory that contains service protocol buffers,
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plus packages required for connectivity to make API calls. App Engine apps
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should not directly import any package under `internal`.
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## Updating a Go App Engine app
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This section describes how to update an older Go App Engine app to use
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these packages. A provided tool, `aefix`, can help automate steps 2 and 3
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(run `go get google.golang.org/appengine/cmd/aefix` to install it), but
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read the details below since `aefix` can't perform all the changes.
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### 1. Update YAML files (App Engine flexible environment / Managed VMs only)
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The `app.yaml` file (and YAML files for modules) should have these new lines added:
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```
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vm: true
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```
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See https://cloud.google.com/appengine/docs/go/modules/#Go_Instance_scaling_and_class for details.
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### 2. Update import paths
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The import paths for App Engine packages are now fully qualified, based at `google.golang.org/appengine`.
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You will need to update your code to use import paths starting with that; for instance,
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code importing `appengine/datastore` will now need to import `google.golang.org/appengine/datastore`.
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### 3. Update code using deprecated, removed or modified APIs
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Most App Engine services are available with exactly the same API.
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A few APIs were cleaned up, and some are not available yet.
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This list summarises the differences:
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* `appengine.Context` has been replaced with the `Context` type from `golang.org/x/net/context`.
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* Logging methods that were on `appengine.Context` are now functions in `google.golang.org/appengine/log`.
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* `appengine.Timeout` has been removed. Use `context.WithTimeout` instead.
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* `appengine.Datacenter` now takes a `context.Context` argument.
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* `datastore.PropertyLoadSaver` has been simplified to use slices in place of channels.
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* `delay.Call` now returns an error.
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* `search.FieldLoadSaver` now handles document metadata.
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* `urlfetch.Transport` no longer has a Deadline field; set a deadline on the
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`context.Context` instead.
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* `aetest` no longer declares its own Context type, and uses the standard one instead.
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* `taskqueue.QueueStats` no longer takes a maxTasks argument. That argument has been
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deprecated and unused for a long time.
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* `appengine.BackendHostname` and `appengine.BackendInstance` were for the deprecated backends feature.
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Use `appengine.ModuleHostname`and `appengine.ModuleName` instead.
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* Most of `appengine/file` and parts of `appengine/blobstore` are deprecated.
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Use [Google Cloud Storage](https://godoc.org/cloud.google.com/go/storage) if the
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feature you require is not present in the new
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[blobstore package](https://google.golang.org/appengine/blobstore).
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* `appengine/socket` is not required on App Engine flexible environment / Managed VMs.
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Use the standard `net` package instead.
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