Using the Go platform

The AWS App Runner Go platform provides managed runtimes. Each runtime makes it easy to build and run containers with web applications based on a Go version. When you use a Go runtime, App Runner starts with a managed Go runtime image. This image is based on the Amazon Linux Docker image and contains the runtime package for a version of Go and some tools. App Runner uses this managed runtime image as a base image, and adds your application code to build a Docker image. It then deploys this image to run your web service in a container.

You specify a runtime for your App Runner service when you create a service using the App Runner console or the CreateService API operation. You can also specify a runtime as part of your source code. Use the runtime keyword in a App Runner configuration file that you include in your code repository. The naming convention of a managed runtime is <language-name><major-version>.

For valid Go runtime names and versions, see Go 1 runtime release information.

App Runner updates the runtime for your service to the latest version on every deployment or service update. If your application requires a specific version of a managed runtime, you can specify it using the runtime-version keyword in the App Runner configuration file. You can lock to any level of version, including a major or minor version. App Runner only makes lower-level updates to the runtime of your service.

Version syntax for Go runtimes: major[.minor[.patch]]

For example: 1.18.7

The following examples demonstrate version locking:

• 1.18 – Lock the major and minor versions. App Runner updates only patch versions.

• 1.18.7 – Lock to a specific patch version. App Runner doesn't update your runtime version.

Topics

• Go runtime configuration
• Go runtime examples
• Go 1 runtime release information

Go runtime configuration

When you choose a managed runtime, you must also configure, as a minimum, build and run commands. You configure them while creating or updating your App Runner service. You can do this using one of the following methods:

• Using the App Runner console – Specify the commands in the Configure build section of the creation process or configuration tab.

• Using the App Runner API – Call the CreateService or UpdateService API operation. Specify the commands using the BuildCommand and StartCommand members of the CodeConfigurationValues data type.

• Using a configuration file – Specify one or more build commands in up to three build phases, and a single run command that serves to start your application. There are additional optional configuration settings.

Providing a configuration file is optional. When you create an App Runner service using the console or the API, you specify if App Runner gets your configuration settings directly when it's created or from a configuration file.

Go runtime examples

The following examples show App Runner configuration files for building and running a Go service.

Minimal Go configuration file

This example shows a minimal configuration file that you can use with a Go managed runtime. For the assumptions that App Runner makes with a minimal configuration file, see Configuration file examples.

Example apprunner.yaml

version: 1.0
runtime: go1
build:
  commands:
    build:
      - go build main.go
run:
  command: ./main

Extended Go configuration file

This example shows the use of all the configuration keys with a Go managed runtime.

Note

The runtime version that's used in these examples is 1.18.7. You can replace it with a version you want to use. For latest supported Go runtime version, see Go 1 runtime release information.

Example apprunner.yaml

version: 1.0
runtime: go1
build:
  commands:
     pre-build:
      - scripts/prebuild.sh
    build:
      - go build main.go
    post-build:
      - scripts/postbuild.sh
  env:
    - name: MY_VAR_EXAMPLE
      value: "example"
run:
  runtime-version: 1.18.7
  command: ./main
  network:
    port: 3000
    env: APP_PORT
  env:
    - name: MY_VAR_EXAMPLE
      value: "example"

Complete Go application source

These examples shows the source code for a complete Go application that you can deploy to a Go runtime service.

Example main.go

package main
import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprint(w, "<h1>Welcome to App Runner</h1>")
    })
    fmt.Println("Starting the server on :3000...")
    http.ListenAndServe(":3000", nil)
}

Example apprunner.yaml

version: 1.0
runtime: go1
build:
  commands:
    build:
      - go build main.go
run:
  command: ./main
  network:
    port: 3000
    env: APP_PORT