support passing in platform as flag

railwayapp · Feb 5, 2025 · 293ae93 · 293ae93
1 parent 1089655
commit 293ae93
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Showing 4 changed files with 32 additions and 3 deletions.
diff --git a/buildkit/build.go b/buildkit/build.go
@@ -30,6 +30,7 @@ type BuildWithBuildkitClientOptions struct {
 	ProgressMode string
 	SecretsHash  string
 	Secrets      map[string]string
+	Platform     BuildPlatform
 }
 
 func BuildWithBuildkitClient(appDir string, plan *plan.BuildPlan, opts BuildWithBuildkitClientOptions) error {
@@ -60,7 +61,10 @@ func BuildWithBuildkitClient(appDir string, plan *plan.BuildPlan, opts BuildWith
 		return fmt.Errorf("failed to get buildkit info: %w", err)
 	}
 
-	buildPlatform := determineBuildPlatformFromHost()
+	buildPlatform := opts.Platform
+	if (buildPlatform == BuildPlatform{}) {
+		buildPlatform = DetermineBuildPlatformFromHost()
+	}
 
 	llbState, image, err := ConvertPlanToLLB(plan, ConvertPlanOptions{
 		BuildPlatform: buildPlatform,

diff --git a/buildkit/frontend.go b/buildkit/frontend.go
@@ -117,7 +117,7 @@ func validatePlatform(opts map[string]string) (BuildPlatform, error) {
 	platformStr := opts["platform"]
 	if platformStr == "" {
 		// Default to host platform if none specified
-		return determineBuildPlatformFromHost(), nil
+		return DetermineBuildPlatformFromHost(), nil
 	}
 
 	// Error if multiple platforms are specified

diff --git a/buildkit/platform.go b/buildkit/platform.go
@@ -25,7 +25,7 @@ var (
 	}
 )
 
-func determineBuildPlatformFromHost() BuildPlatform {
+func DetermineBuildPlatformFromHost() BuildPlatform {
 	if runtime.GOARCH == "arm64" {
 		return PlatformLinuxARM64
 	}

diff --git a/cli/build.go b/cli/build.go
@@ -28,6 +28,10 @@ var BuildCommand = &cli.Command{
 			Name:  "output",
 			Usage: "output the final filesystem to a local directory",
 		},
+		&cli.StringFlag{
+			Name:  "platform",
+			Usage: "platform to build for (e.g. linux/amd64, linux/arm64)",
+		},
 		&cli.StringFlag{
 			Name:  "progress",
 			Usage: "buildkit progress output mode. Values: auto, plain, tty",
@@ -63,13 +67,19 @@ var BuildCommand = &cli.Command{
 
 		secretsHash := getSecretsHash(env)
 
+		platform, err := getPlatform(cmd.String("platform"))
+		if err != nil {
+			return cli.Exit(err, 1)
+		}
+
 		err = buildkit.BuildWithBuildkitClient(app.Source, buildResult.Plan, buildkit.BuildWithBuildkitClientOptions{
 			ImageName:    cmd.String("name"),
 			DumpLLB:      cmd.Bool("llb"),
 			OutputDir:    cmd.String("output"),
 			ProgressMode: cmd.String("progress"),
 			SecretsHash:  secretsHash,
 			Secrets:      env.Variables,
+			Platform:     platform,
 		})
 		if err != nil {
 			return cli.Exit(err, 1)
@@ -79,6 +89,21 @@ var BuildCommand = &cli.Command{
 	},
 }
 
+func getPlatform(platformStr string) (buildkit.BuildPlatform, error) {
+	var platform buildkit.BuildPlatform
+	if platformStr == "" {
+		platform = buildkit.DetermineBuildPlatformFromHost()
+	} else if platformStr == "linux/arm64" {
+		platform = buildkit.PlatformLinuxARM64
+	} else if platformStr != "linux/amd64" {
+		return buildkit.BuildPlatform{}, fmt.Errorf("unsupported platform: %s. Must be one of: linux/amd64, linux/arm64", platformStr)
+	} else {
+		platform = buildkit.PlatformLinuxAMD64
+	}
+
+	return platform, nil
+}
+
 func validateSecrets(plan *plan.BuildPlan, env *app.Environment) error {
 	for _, secret := range plan.Secrets {
 		if _, ok := env.Variables[secret]; !ok {