The Go runtime is the software stack responsible for installing your application code and dependencies, and then running that application in the flexible environment.
Version
1.18
and later are built using buildpacks, which requires you to choose an operating system in yourapp.yaml
file. For example, to use Go 1.22, you must specify Ubuntu 22 as the operating system.Version
1.15
and earlier are built using Docker.
For the full list of supported Go versions, and their corresponding Ubuntu version, see the Runtime support schedule.
Choose a Go version
New runtime versions
For Go runtime version 1.18 and later, you must include the
runtime_config
and operating_system
settings in your
app.yaml
to specify an operating system.
To use the new runtimes, you must install gcloud CLI
version 420.0.0 or later. You can update your CLI tooling
by running the gcloud components update
command. To view your installed version, you can run the gcloud version
command.
Go recommends that you use a go.mod
file for managing dependencies.
To install dependencies during deployment, include a go.mod
file in the same folder as
the app.yaml
file.
For example, the folder structure of your app with go.mod
must represent:
<application-root>/
--> app.yaml
--> go.mod
--> Other source files used in your application.
Optionally, you can specify a runtime version by including the runtime_version
setting in your app.yaml
. By default, the latest Go version is used if
the runtime_version
setting is not specified.
Examples
To specify Go 1.22 on Ubuntu 22:
runtime: go env: flex runtime_config: operating_system: "ubuntu22" runtime_version: "1.22"
To specify the latest supported Go version on Ubuntu 22:
runtime: go env: flex runtime_config: operating_system: "ubuntu22"
Your app uses the latest stable release of the version that is specified in your
app.yaml
file. App Engine automatically updates to new patch revisions, but
it won't automatically update the major version.
For example, your application might be deployed at Go 1.18.10, and later it might be automatically updated to Go 1.18.11, but it won't be automatically updated to the major version Go 1.19.
Choosing Go 1.22 in your app.yaml
file results in
the latest patch
version of Go 1.22 available.
runtime: go
env: flex
runtime_config:
operating_system: "ubuntu22"
runtime_version: "1.22"
See the app.yaml
reference for more information.
Previous runtime versions
For Go version 1.15 and earlier, you specify a version using the go1.x
format in app.yaml
config file as
runtime: go1.x
:
Example
runtime: go1.14 env: flex
If no version is specified, the default version of go1.11
will be automatically
selected.
Your app uses the latest stable release of the version that is specified in your
app.yaml
file. App Engine automatically updates to new patch revisions, but
it won't automatically update the major version.
For example, your application might be deployed at Go 1.14.10, and later it might be automatically updated to Go 1.14.11, but it won't be automatically updated to the major version Go 1.15.
Choosing the go runtime version go1.15
in your app.yaml
file results in
the latest version of 1.15 available, for example, 1.15.15.
runtime: go1.15 env: flex
Import packages
Your code compiles when you deploy your app to App Engine. When you
run the deployment command, your app's dependencies are first collected from
your local GOPATH
and then they are all sent to the build server. Any missing
dependencies, for example third-party libraries, results in build failures.
To avoid build failures and ensure that all your app's dependencies get deployed with your code, you should test your app locally before deploying it.
Extending the runtime
For instructions on how to extend and customize the Go runtime, read the Go runtime builder on GitHub.
Metadata server
Each instance of your application can use the Compute Engine metadata server to query information about the instance, including its host name, external IP address, instance ID, custom metadata, and service account information. App Engine does not allow you to set custom metadata for each instance, but you can set project-wide custom metadata and read it from your App Engine and Compute Engine instances.
Use the
cloud.google.com/go/compute/metadata
package to access the metadata server.