Add support for --docker_platform flag (#994)

* Add support for --platform when executing docker create

Signed-off-by: Thomas Lam <thomaslam@canva.com>

* Undo redundant changes

Signed-off-by: Thomas Lam <thomaslam@canva.com>

---------

Signed-off-by: Thomas Lam <thomaslam@canva.com>
Co-authored-by: DaveGay <davegay@google.com>

cmd/rbe_configs_gen/rbe_configs_gen.go

@@ -32,6 +32,7 @@ var (
 	toolchainContainer = flag.String("toolchain_container", "", "Repository path to toolchain image to generate configs for. E.g., l.gcr.io/google/rbe-ubuntu16-04:latest")
 	execOS             = flag.String("exec_os", "", "The OS (linux|windows) of the toolchain container image a.k.a, the execution platform in Bazel.")
 	targetOS           = flag.String("target_os", "", "The OS (linux|windows) artifacts built will target a.k.a, the target platform in Bazel.")
+	dockerPlatform     = flag.String("docker_platform", "", "(Optional) Set platform when creating container, if given the Docker server is multi-platform capable.")
 
 	// Optional input arguments.
 	bazelVersion = flag.String("bazel_version", "", "(Optional) Bazel release version to generate configs for. E.g., 4.0.0. If unspecified, the latest available Bazel release is picked.")
@@ -158,6 +159,7 @@ func main() {
 		BazelVersion:           *bazelVersion,
 		BazelPath:              *bazelPath,
 		ToolchainContainer:     *toolchainContainer,
+		DockerPlatform:         *dockerPlatform,
 		ExecOS:                 *execOS,
 		TargetOS:               *targetOS,
 		OutputTarball:          *outputTarball,

pkg/rbeconfigsgen/options.go

@@ -36,6 +36,8 @@ type Options struct {
 	BazelPath string
 	// ToolchainContainer is the docker image of the toolchain container to generate configs for.
 	ToolchainContainer string
+	// Specify --platform when executing docker create.
+	DockerPlatform string
 	// ExecOS is the OS of the toolchain container image or the OS in which the build actions will
 	// execute.
 	ExecOS string
@@ -273,6 +275,7 @@ func (o *Options) Validate() error {
 	log.Printf("ToolchainContainer=%q", o.ToolchainContainer)
 	log.Printf("ExecOS=%q", o.ExecOS)
 	log.Printf("TargetOS=%q", o.TargetOS)
+	log.Printf("DockerPlatform=%q", o.DockerPlatform)
 	log.Printf("OutputTarball=%q", o.OutputTarball)
 	log.Printf("OutputSourceRoot=%q", o.OutputSourceRoot)
 	log.Printf("OutputConfigPath=%q", o.OutputConfigPath)

pkg/rbeconfigsgen/rbeconfigsgen.go

@@ -251,7 +251,7 @@ func BazeliskDownloadInfo(os string) (string, string, error) {
 // newDockerRunner creates a new running container of the given containerImage. stopContainer
 // determines if the cleanup function on the dockerRunner will stop the running container when
 // called.
-func newDockerRunner(containerImage string, stopContainer bool) (*dockerRunner, error) {
+func newDockerRunner(containerImage string, dockerPlatform string, stopContainer bool) (*dockerRunner, error) {
 	if containerImage == "" {
 		return nil, fmt.Errorf("container image was not specified")
 	}
@@ -271,7 +271,13 @@ func newDockerRunner(containerImage string, stopContainer bool) (*dockerRunner,
 	log.Printf("Resolved toolchain image %q to fully qualified reference %q.", d.containerImage, resolvedImage)
 	d.resolvedImage = resolvedImage
 
-	cid, err := runCmd(d.dockerPath, "create", "--rm", d.resolvedImage, "sleep", "infinity")
+	args := []string{"create", "--rm"}
+	if dockerPlatform != "" {
+		args = append(args, "--platform", dockerPlatform)
+	}
+	args = append(args, d.resolvedImage, "sleep", "infinity")
+
+	cid, err := runCmd(d.dockerPath, args...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create a container with the toolchain container image: %w", err)
 	}
@@ -982,7 +988,7 @@ func Run(o Options) error {
 	if err := processTempDir(&o); err != nil {
 		return fmt.Errorf("unable to initialize a local temporary working directory to store intermediate files: %w", err)
 	}
-	d, err := newDockerRunner(o.ToolchainContainer, o.Cleanup)
+	d, err := newDockerRunner(o.ToolchainContainer, o.DockerPlatform, o.Cleanup)
 	if err != nil {
 		return fmt.Errorf("failed to initialize a docker container: %w", err)
 	}