feat: add ftl box command tree (#1878)

There are two commands:

`ftl box build <image>` builds a self-contained Docker container with a
set of modules.

`ftl box run` runs modules inside an ftl-in-a-box container (currently
does nothing).

Dockerfile.box

@@ -41,8 +41,10 @@ COPY --from=builder /hermit/pkg/openjre-18.0.2.1_1/ ./jre/
 COPY --from=builder /src/build/template template
 COPY --from=builder /src/build/release/ftl .
 RUN mkdir deployments
+# Where the module artifacts are stored
+RUN mkdir modules
 
 EXPOSE 8891
 EXPOSE 8892
 
-CMD ["/root/ftl", "dev"]
+CMD ["/root/ftl", "box", "run"]

buildengine/deploy.go

@@ -41,7 +41,7 @@ func Deploy(ctx context.Context, module Module, replicas int32, waitForDeployOnl
 	logger.Infof("Deploying module")
 
 	moduleConfig := module.Config.Abs()
-	files, err := findFiles(moduleConfig)
+	files, err := FindFilesToDeploy(moduleConfig)
 	if err != nil {
 		logger.Errorf(err, "failed to find files in %s", moduleConfig)
 		return err
@@ -154,7 +154,8 @@ func loadProtoSchema(config moduleconfig.AbsModuleConfig, replicas int32) (*sche
 	return module, nil
 }
 
-func findFiles(moduleConfig moduleconfig.AbsModuleConfig) ([]string, error) {
+// FindFilesToDeploy returns a list of files to deploy for the given module.
+func FindFilesToDeploy(moduleConfig moduleconfig.AbsModuleConfig) ([]string, error) {
 	var out []string
 	for _, file := range moduleConfig.Deploy {
 		info, err := os.Stat(file)

cmd/ftl/cmd_box.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/otiai10/copy"
+
+	"github.com/TBD54566975/ftl"
+	"github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
+	"github.com/TBD54566975/ftl/buildengine"
+	"github.com/TBD54566975/ftl/common/projectconfig"
+	"github.com/TBD54566975/ftl/internal/exec"
+	"github.com/TBD54566975/ftl/internal/log"
+)
+
+const boxDockerFile = `FROM {{.BaseImage}}
+
+WORKDIR /root
+
+COPY modules /root
+
+EXPOSE 8891
+EXPOSE 8892
+
+CMD ["/root/ftl", "dev"]
+
+`
+
+type boxCmd struct {
+	Build boxBuildCmd `cmd:"" help:"Build a self-contained Docker container (FTL-in-a-box) for running a set of modules."`
+	Run   boxRunCmd   `cmd:"" help:"Run an FTL-in-a-box container."`
+}
+
+type boxRunCmd struct {
+}
+
+func (b *boxRunCmd) Run() error {
+	return fmt.Errorf("not implemented")
+}
+
+type boxBuildCmd struct {
+	BaseImage   string   `help:"Name of the ftl-box Docker image to use as a base." default:"ftl0/ftl-box:${version}"`
+	Parallelism int      `short:"j" help:"Number of modules to build in parallel." default:"${numcpu}"`
+	Image       string   `arg:"" help:"Name of image to build."`
+	Dirs        []string `arg:"" help:"Base directories containing modules (defaults to modules in project config)." type:"existingdir" optional:""`
+}
+
+func (b *boxBuildCmd) Help() string {
+	return ``
+}
+
+func (b *boxBuildCmd) Run(ctx context.Context, client ftlv1connect.ControllerServiceClient, projConfig projectconfig.Config) error {
+	if len(b.Dirs) == 0 {
+		b.Dirs = projConfig.AbsModuleDirs()
+	}
+	if len(b.Dirs) == 0 {
+		return errors.New("no directories specified")
+	}
+	engine, err := buildengine.New(ctx, client, b.Dirs, buildengine.Parallelism(b.Parallelism))
+	if err != nil {
+		return err
+	}
+	if err := os.Setenv("GOOS", "linux"); err != nil {
+		return fmt.Errorf("failed to set GOOS: %w", err)
+	}
+	if err := os.Setenv("GOARCH", "amd64"); err != nil {
+		return fmt.Errorf("failed to set GOARCH: %w", err)
+	}
+	if err := engine.Build(ctx); err != nil {
+		return fmt.Errorf("build failed: %w", err)
+	}
+
+	workDir, err := os.MkdirTemp("", "ftl-box-")
+	if err != nil {
+		return fmt.Errorf("failed to create temporary directory: %w", err)
+	}
+	defer os.RemoveAll(workDir) //nolint:errcheck
+	logger := log.FromContext(ctx)
+	logger.Debugf("Copying")
+	if err := engine.Each(func(m buildengine.Module) error {
+		config := m.Config.Abs()
+		destDir := filepath.Join(workDir, "modules", config.Module)
+
+		// Copy deployment artefacts.
+		files, err := buildengine.FindFilesToDeploy(config)
+		if err != nil {
+			return err
+		}
+		files = append(files, filepath.Join(config.Dir, "ftl.toml"))
+		for _, file := range files {
+			relFile, err := filepath.Rel(config.Dir, file)
+			if err != nil {
+				return err
+			}
+			destFile := filepath.Join(destDir, relFile)
+			logger.Debugf(" %s -> %s", file, destFile)
+			if err := copy.Copy(file, destFile); err != nil {
+				return fmt.Errorf("failed to copy %s to %s: %w", file, destFile, err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return err
+	}
+	baseImage := b.BaseImage
+	baseImageParts := strings.Split(baseImage, ":")
+	if len(baseImageParts) == 2 {
+		version := baseImageParts[1]
+		if !ftl.IsRelease(version) {
+			version = "latest"
+		}
+		baseImage = baseImageParts[0] + ":" + version
+	}
+	dockerFile := strings.ReplaceAll(boxDockerFile, "{{.BaseImage}}", baseImage)
+	err = os.WriteFile(filepath.Join(workDir, "Dockerfile"), []byte(dockerFile), 0600)
+	if err != nil {
+		return fmt.Errorf("failed to write Dockerfile: %w", err)
+	}
+	return exec.Command(ctx, log.Info, workDir, "docker", "build", "-t", b.Image, "--progress=plain", "--platform=linux/amd64", ".").Run()
+}

cmd/ftl/main.go

@@ -44,6 +44,7 @@ type CLI struct {
 	Kill     killCmd     `cmd:"" help:"Kill a deployment."`
 	Schema   schemaCmd   `cmd:"" help:"FTL schema commands."`
 	Build    buildCmd    `cmd:"" help:"Build all modules found in the specified directories."`
+	Box      boxCmd      `cmd:"" help:"Build a self-contained Docker container for running a set of module."`
 	Deploy   deployCmd   `cmd:"" help:"Build and deploy all modules found in the specified directories."`
 	Download downloadCmd `cmd:"" help:"Download a deployment."`
 	Secret   secretCmd   `cmd:"" help:"Manage secrets."`

common/moduleconfig/moduleconfig.go

@@ -105,11 +105,6 @@ func (c ModuleConfig) Abs() AbsModuleConfig {
 	return AbsModuleConfig(clone)
 }
 
-// AbsDeployDir returns the absolute path to the deploy directory.
-func (c ModuleConfig) AbsDeployDir() string {
-	return filepath.Join(c.Dir, c.DeployDir)
-}
-
 func setConfigDefaults(moduleDir string, config *ModuleConfig) error {
 	if config.Realm == "" {
 		config.Realm = "home"