add experimental feature to enable zstd for depot builds (#4065)

internal/appconfig/config.go

@@ -163,6 +163,7 @@ type Experimental struct {
 	LazyLoadImages bool     `toml:"lazy_load_images,omitempty" json:"lazy_load_images,omitempty"`
 	Attached       Attached `toml:"attached,omitempty" json:"attached,omitempty"`
 	MachineConfig  string   `toml:"machine_config,omitempty" json:"machine_config,omitempty"`
+	UseZstd        bool     `toml:"use_zstd,omitempty" json:"use_zstd,omitempty"`
 }
 
 type Attached struct {

internal/build/imgsrc/depot.go

@@ -256,6 +256,12 @@ func buildImage(ctx context.Context, buildkitClient *client.Client, opts ImageOp
 		exportEntry.Attrs["push"] = "true"
 	}
 
+	if opts.UseZstd {
+		exportEntry.Attrs["compression"] = "zstd"
+		exportEntry.Attrs["compression-level"] = "3"
+		exportEntry.Attrs["force-compression"] = "true"
+	}
+
 	ch := make(chan *client.SolveStatus)
 	eg, ctx := errgroup.WithContext(ctx)
 	eg.Go(func() error {

internal/build/imgsrc/resolver.go

@@ -54,6 +54,7 @@ type ImageOptions struct {
 	BuildpacksDockerHost string
 	BuildpacksVolumes    []string
 	UseOverlaybd         bool
+	UseZstd              bool
 }
 
 func (io ImageOptions) ToSpanAttributes() []attribute.KeyValue {
@@ -72,6 +73,7 @@ func (io ImageOptions) ToSpanAttributes() []attribute.KeyValue {
 		attribute.String("imageoptions.buildpacks_docker_host", io.BuildpacksDockerHost),
 		attribute.StringSlice("imageoptions.buildpacks", io.Buildpacks),
 		attribute.StringSlice("imageoptions.buildpacks_volumes", io.BuildpacksVolumes),
+		attribute.Bool("imageoptions.use_zstd", io.UseZstd),
 	}
 
 	if io.BuildArgs != nil {

internal/command/command_run.go

@@ -73,6 +73,15 @@ func DetermineImage(ctx context.Context, appName string, imageOrPath string) (im
 		}
 		opts.BuildArgs = extraArgs
 
+		if cfg != nil && cfg.Experimental != nil {
+			opts.UseZstd = cfg.Experimental.UseZstd
+		}
+
+		// use-zstd passed through flags takes precedence over the one set in config
+		if flag.IsSpecified(ctx, "use-zstd") {
+			opts.UseZstd = flag.GetBool(ctx, "use-zstd")
+		}
+
 		img, err = resolver.BuildImage(ctx, io, opts)
 		if err != nil {
 			return nil, err

internal/command/deploy/deploy_build.go

@@ -134,6 +134,8 @@ func determineImage(ctx context.Context, appConfig *appconfig.Config, useWG, rec
 
 	if appConfig.Experimental != nil {
 		opts.UseOverlaybd = appConfig.Experimental.LazyLoadImages
+
+		opts.UseZstd = appConfig.Experimental.UseZstd
 	}
 
 	// flyctl supports key=value form while Docker supports id=key,src=/path/to/secret form.

internal/command/machine/run.go

@@ -180,6 +180,10 @@ var runOrCreateFlags = flag.Set{
 		Description: "Enable LSVD for this machine",
 		Hidden:      true,
 	},
+	flag.Bool{
+		Name:        "use-zstd",
+		Description: "Enable zstd compression for the image",
+	},
 }
 
 func soManyErrors(args ...interface{}) error {