71 lines
3.3 KiB
Markdown
71 lines
3.3 KiB
Markdown
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# Go App Engine for Managed VMs
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[](https://travis-ci.org/golang/appengine)
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This repository supports the Go runtime for Managed VMs on App Engine.
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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/managed-vms/
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for more information.
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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 a traditional Go App Engine app to run on Managed VMs.
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### 1. Update YAML files
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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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manual_scaling:
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instances: 1
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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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You can do that manually, or by running this command to recursively update all Go source files in the current directory:
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(may require GNU sed)
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```
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sed -i '/"appengine/{s,"appengine,"google.golang.org/appengine,;s,appengine_,appengine/,}' \
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$(find . -name '*.go')
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```
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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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* `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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* `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/aetest`, `appengine/blobstore`, `appengine/cloudsql`
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and `appengine/runtime` have not been ported yet.
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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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* `appengine.IsCapabilityDisabled` and `appengine/capability` are obsolete.
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* Most of `appengine/file` is deprecated. Use [Google Cloud Storage](https://godoc.org/google.golang.org/cloud/storage) instead.
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* `appengine/socket` is deprecated. Use the standard `net` package instead.
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