component: refactor to consistently use absolute paths

Testing is problematic because the current working directory is not the
platform root.  This patch refactors the codebase to consistently store
and use the platform root directory to construct absolute paths for
reading and writing files during a BuldPlan execution.

internal/artifact/artifact.go

@@ -8,8 +8,6 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
-
-	"github.com/holos-run/holos/internal/errors"
 )
 
 // NewStore should provide a concrete Store.
@@ -54,7 +52,7 @@ func (a *MapStore) Set(path string, data []byte) error {
 	a.mu.Lock()
 	defer a.mu.Unlock()
 	if _, ok := a.m[path]; ok {
-		return errors.Format("%s already set", path)
+		return fmt.Errorf("%s already set", path)
 	}
 	a.m[path] = data
 	slog.Debug(fmt.Sprintf("store: set path %s", path), "component", "store", "op", "set", "path", path, "bytes", len(data))
@@ -70,10 +68,15 @@ func (a *MapStore) Get(path string) (data []byte, ok bool) {
 	return
 }
 
-// Save writes a file or directory tree to the filesystem.
+// Save writes a file or directory tree to the filesystem.  dir must be an
+// absolute path.
 func (a *MapStore) Save(dir, path string) error {
+	if !filepath.IsAbs(dir) {
+		return fmt.Errorf("path not absolute: %s", dir)
+	}
+
 	if strings.HasSuffix(path, "/") {
-		return errors.Format("path must not end in a /")
+		return fmt.Errorf("path must not end in a /: %s", path)
 	}
 
 	fullPath := filepath.Join(dir, path)
@@ -82,10 +85,10 @@ func (a *MapStore) Save(dir, path string) error {
 	// Save a single file and return.
 	if data, ok := a.Get(path); ok {
 		if err := os.MkdirAll(filepath.Dir(fullPath), 0777); err != nil {
-			return errors.Format("%s: %w", msg, err)
+			return fmt.Errorf("%s: %w", msg, err)
 		}
 		if err := os.WriteFile(fullPath, data, 0666); err != nil {
-			return errors.Format("%s: %w", msg, err)
+			return fmt.Errorf("%s: %w", msg, err)
 		}
 		return nil
 	}
@@ -98,10 +101,10 @@ func (a *MapStore) Save(dir, path string) error {
 			data, _ := a.Get(key)
 			fullPath = filepath.Join(dir, key)
 			if err := os.MkdirAll(filepath.Dir(fullPath), 0777); err != nil {
-				return errors.Format("%s: %w", msg, err)
+				return fmt.Errorf("%s: %w", msg, err)
 			}
 			if err := os.WriteFile(fullPath, data, 0666); err != nil {
-				return errors.Format("%s: %w", msg, err)
+				return fmt.Errorf("%s: %w", msg, err)
 			}
 		}
 	}
@@ -111,28 +114,31 @@ func (a *MapStore) Save(dir, path string) error {
 
 // Load saves a file or directory tree to the store.
 func (a *MapStore) Load(dir, path string) error {
-	fileSystem := os.DirFS(dir)
-	err := fs.WalkDir(fileSystem, path, func(path string, d fs.DirEntry, err error) error {
+	if !filepath.IsAbs(dir) {
+		return fmt.Errorf("path not absolute: %s", dir)
+	}
+	fsys := os.DirFS(dir)
+	err := fs.WalkDir(fsys, path, func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
-			return errors.Wrap(err)
+			return err
 		}
 		// Skip over directories.
 		if d.IsDir() {
 			return nil
 		}
 		// Load files into the store.
-		data, err := fs.ReadFile(fileSystem, path)
+		data, err := fs.ReadFile(fsys, path)
 		if err != nil {
-			return errors.Wrap(err)
+			return err
 		}
 		if err := a.Set(path, data); err != nil {
-			return errors.Wrap(err)
+			return err
 		}
 
 		return nil
 	})
 	if err != nil {
-		return errors.Wrap(err)
+		return err
 	}
 
 	return nil

internal/cli/show.go

@@ -31,8 +31,8 @@ func NewShowCmd(cfg *platform.Config) (cmd *cobra.Command) {
 	cmd.AddCommand(spCmd)
 
 	sbp := &showBuildPlans{
-		Format: "yaml",
-		Out:    cfg.Stdout,
+		format: "yaml",
+		cfg:    cfg,
 	}
 	sbCmd := platform.NewCommand(cfg, sbp.Run)
 	sbCmd.Use = "buildplans"
@@ -66,18 +66,18 @@ func (s *showPlatform) Run(ctx context.Context, p *platform.Platform) error {
 }
 
 type showBuildPlans struct {
-	Format string
-	Out    io.Writer
+	format string
+	cfg    *platform.Config
 }
 
 func (s *showBuildPlans) flagSet() *pflag.FlagSet {
 	fs := pflag.NewFlagSet("", pflag.ContinueOnError)
-	fs.StringVar(&s.Format, "format", "yaml", "yaml or json format")
+	fs.StringVar(&s.format, "format", "yaml", "yaml or json format")
 	return fs
 }
 
 func (s *showBuildPlans) Run(ctx context.Context, p *platform.Platform) error {
-	encoder, err := holos.NewSequentialEncoder(s.Format, s.Out)
+	encoder, err := holos.NewSequentialEncoder(s.format, s.cfg.Stdout)
 	if err != nil {
 		return errors.Wrap(err)
 	}
@@ -90,8 +90,7 @@ func (s *showBuildPlans) Run(ctx context.Context, p *platform.Platform) error {
 			if err != nil {
 				return errors.Wrap(err)
 			}
-			opts := holos.NewBuildOpts(pc.Path())
-			opts.BuildContext.TempDir = "${TMPDIR_PLACEHOLDER}"
+			opts := holos.NewBuildOpts(p.Root(), pc.Path(), s.cfg.WriteTo, "${TMPDIR_PLACEHOLDER}")
 
 			// TODO(jjm): refactor into [holos.NewBuildOpts] as functional options.
 			// Component name, label, annotations passed via tags to cue.

internal/component/component.go

@@ -95,7 +95,7 @@ func (c *Component) BuildPlan(tm holos.TypeMeta, opts holos.BuildOpts) (BuildPla
 	switch tm.APIVersion {
 	case "v1alpha6":
 		// Prepare runtime build context for injection as a cue tag.
-		bc := v1alpha6.NewBuildContext(opts.BuildContext)
+		bc := v1alpha6.NewBuildContext(opts.TempDir())
 		buildContextTags, err := bc.Tags()
 		if err != nil {
 			return bp, errors.Format("could not get build context tag: %w", err)
@@ -150,11 +150,9 @@ func (c *Component) render(ctx context.Context, tm holos.TypeMeta) error {
 	defer util.Remove(ctx, tempDir)
 
 	// Runtime configuration of the build.
-	opts := holos.NewBuildOpts(c.Path)
+	opts := holos.NewBuildOpts(c.Root, c.Path, c.WriteTo, tempDir)
 	opts.Stderr = c.Stderr
 	opts.Concurrency = c.Concurrency
-	opts.WriteTo = filepath.Join(c.Root, c.WriteTo)
-	opts.BuildContext.TempDir = tempDir
 
 	log := logger.FromContext(ctx)
 	log.DebugContext(ctx, fmt.Sprintf("rendering %s kind %s version %s", c.Path, tm.Kind, tm.APIVersion), "kind", tm.Kind, "apiVersion", tm.APIVersion, "path", c.Path)
@@ -187,10 +185,9 @@ func (c *Component) renderAlpha5(ctx context.Context) error {
 	defer util.Remove(ctx, tempDir)
 
 	// Runtime configuration of the build.
-	opts := holos.NewBuildOpts(c.Path)
+	opts := holos.NewBuildOpts(c.Root, c.Path, c.WriteTo, "")
 	opts.Stderr = c.Stderr
 	opts.Concurrency = c.Concurrency
-	opts.WriteTo = filepath.Join(c.Root, c.WriteTo)
 
 	tm := holos.TypeMeta{
 		Kind:       "BuildPlan",

internal/component/v1alpha5/v1alpha5.go

@@ -117,7 +117,12 @@ type taskParams struct {
 }
 
 func (t taskParams) id() string {
-	return fmt.Sprintf("%s:%s/%s", t.opts.Path, t.buildPlanName, t.taskName)
+	return fmt.Sprintf(
+		"%s:%s/%s",
+		filepath.Clean(t.opts.Leaf()),
+		t.buildPlanName,
+		t.taskName,
+	)
 }
 
 type generatorTask struct {
@@ -149,7 +154,7 @@ func (t generatorTask) run(ctx context.Context) error {
 }
 
 func (t generatorTask) file() error {
-	data, err := os.ReadFile(filepath.Join(string(t.opts.Path), string(t.generator.File.Source)))
+	data, err := os.ReadFile(filepath.Join(t.opts.AbsPath(), string(t.generator.File.Source)))
 	if err != nil {
 		return errors.Wrap(err)
 	}
@@ -162,7 +167,7 @@ func (t generatorTask) file() error {
 func (t generatorTask) helm(ctx context.Context) error {
 	h := t.generator.Helm
 	// Cache the chart by version to pull new versions. (#273)
-	cacheDir := filepath.Join(string(t.opts.Path), "vendor", t.generator.Helm.Chart.Version)
+	cacheDir := filepath.Join(t.opts.AbsPath(), "vendor", t.generator.Helm.Chart.Version)
 	cachePath := filepath.Join(cacheDir, filepath.Base(h.Chart.Name))
 
 	log := logger.FromContext(ctx)
@@ -455,11 +460,11 @@ func buildArtifact(ctx context.Context, idx int, artifact core.Artifact, tasks c
 
 	// Write the final artifact
 	out := string(artifact.Artifact)
-	if err := opts.Store.Save(opts.WriteTo, out); err != nil {
+	if err := opts.Store.Save(opts.AbsWriteTo(), out); err != nil {
 		return errors.Format("%s: %w", msg, err)
 	}
 	log := logger.FromContext(ctx)
-	log.DebugContext(ctx, fmt.Sprintf("wrote %s", filepath.Join(opts.WriteTo, out)))
+	log.DebugContext(ctx, fmt.Sprintf("wrote %s", filepath.Join(opts.AbsWriteTo(), out)))
 
 	return nil
 }
@@ -472,8 +477,7 @@ type BuildPlan struct {
 
 func (b *BuildPlan) Build(ctx context.Context) error {
 	name := b.BuildPlan.Metadata.Name
-	path := b.Opts.Path
-	log := logger.FromContext(ctx).With("name", name, "path", path)
+	log := logger.FromContext(ctx).With("name", name, "path", filepath.Clean(b.Opts.Leaf()))
 
 	msg := fmt.Sprintf("could not build %s", name)
 	if b.BuildPlan.Spec.Disabled {
@@ -595,7 +599,7 @@ func kustomize(ctx context.Context, t core.Transformer, p taskParams) error {
 		"could not transform %s for %s path %s",
 		t.Output,
 		p.buildPlanName,
-		p.opts.Path,
+		filepath.Clean(p.opts.Leaf()),
 	)
 
 	// Write the kustomization

internal/component/v1alpha6/v1alpha6.go

@@ -24,32 +24,8 @@ import (
 	"helm.sh/helm/v3/pkg/cli"
 )
 
-// Platform represents a platform builder.
-type Platform struct {
-	Platform core.Platform
-}
-
-// Load loads from a cue value.
-func (p *Platform) Load(v cue.Value) error {
-	return errors.Wrap(v.Decode(&p.Platform))
-}
-
-func (p *Platform) Export(encoder holos.Encoder) error {
-	if err := encoder.Encode(&p.Platform); err != nil {
-		return errors.Wrap(err)
-	}
-	return nil
-}
-
-func (p *Platform) Select(selectors ...holos.Selector) []holos.Component {
-	components := make([]holos.Component, 0, len(p.Platform.Spec.Components))
-	for _, component := range p.Platform.Spec.Components {
-		if holos.IsSelected(component.Labels, selectors...) {
-			components = append(components, &Component{component})
-		}
-	}
-	return components
-}
+// TODO(jjm) accept an interface to run commands to inject a mock runner from
+// the tests.
 
 type Component struct {
 	Component core.Component
@@ -122,7 +98,7 @@ func (c *Component) ExtractYAML() ([]string, error) {
 }
 
 var _ holos.BuildPlan = &BuildPlan{}
-var _ task = generatorTask{}
+var _ task = &generatorTask{}
 var _ task = transformersTask{}
 var _ task = validatorTask{}
 
@@ -138,7 +114,16 @@ type taskParams struct {
 }
 
 func (t taskParams) id() string {
-	return fmt.Sprintf("%s:%s/%s", t.opts.Path, t.buildPlanName, t.taskName)
+	path := filepath.Clean(t.opts.Leaf())
+	return fmt.Sprintf("%s:%s/%s", path, t.buildPlanName, t.taskName)
+}
+
+func (t taskParams) tempDir() (string, error) {
+	if tempDir := t.opts.TempDir(); tempDir == "" {
+		return "", errors.Format("missing build context temp directory")
+	} else {
+		return tempDir, nil
+	}
 }
 
 type generatorTask struct {
@@ -147,7 +132,7 @@ type generatorTask struct {
 	wg        *sync.WaitGroup
 }
 
-func (t generatorTask) run(ctx context.Context) error {
+func (t *generatorTask) run(ctx context.Context) error {
 	defer t.wg.Done()
 	msg := fmt.Sprintf("could not build %s", t.id())
 	switch t.generator.Kind {
@@ -163,14 +148,18 @@ func (t generatorTask) run(ctx context.Context) error {
 		if err := t.file(); err != nil {
 			return errors.Format("%s: could not generate file: %w", msg, err)
 		}
+	case "Command":
+		if err := t.command(ctx); err != nil {
+			return errors.Format("%s: could not generate from command: %w", msg, err)
+		}
 	default:
 		return errors.Format("%s: unsupported kind %s", msg, t.generator.Kind)
 	}
 	return nil
 }
 
-func (t generatorTask) file() error {
-	data, err := os.ReadFile(filepath.Join(string(t.opts.Path), string(t.generator.File.Source)))
+func (t *generatorTask) file() error {
+	data, err := os.ReadFile(filepath.Join(t.opts.AbsPath(), string(t.generator.File.Source)))
 	if err != nil {
 		return errors.Wrap(err)
 	}
@@ -180,10 +169,10 @@ func (t generatorTask) file() error {
 	return nil
 }
 
-func (t generatorTask) helm(ctx context.Context) error {
+func (t *generatorTask) helm(ctx context.Context) error {
 	h := t.generator.Helm
 	// Cache the chart by version to pull new versions. (#273)
-	cacheDir := filepath.Join(string(t.opts.Path), "vendor", t.generator.Helm.Chart.Version)
+	cacheDir := filepath.Join(t.opts.AbsPath(), "vendor", t.generator.Helm.Chart.Version)
 	cachePath := filepath.Join(cacheDir, filepath.Base(h.Chart.Name))
 
 	log := logger.FromContext(ctx)
@@ -307,7 +296,7 @@ func (t generatorTask) helm(ctx context.Context) error {
 	return nil
 }
 
-func (t generatorTask) resources() error {
+func (t *generatorTask) resources() error {
 	var size int
 	for _, m := range t.generator.Resources {
 		size += len(m)
@@ -338,6 +327,39 @@ func (t generatorTask) resources() error {
 	return nil
 }
 
+func (t *generatorTask) command(ctx context.Context) error {
+	store := t.opts.Store
+	msg := fmt.Sprintf("could not generate from command %s", t.id())
+
+	args := t.generator.Command.Args
+	if len(args) < 1 {
+		return errors.Format("%s: command args length must be at least 1", msg)
+	}
+
+	r, err := util.RunCmdA(ctx, t.opts.Stderr, args[0], args[1:]...)
+	if err != nil {
+		return errors.Format("%s: %w", msg, err)
+	}
+
+	if t.generator.Command.Stdout {
+		// Store the command stdout as the artifact.
+		if err := store.Set(string(t.generator.Output), r.Stdout.Bytes()); err != nil {
+			return errors.Format("%s: %w", msg, err)
+		}
+	} else {
+		// Store the file tree as the artifact.
+		tempDir, err := t.taskParams.tempDir()
+		if err != nil {
+			return errors.Format("%s: %w", msg, err)
+		}
+		if err := store.Load(tempDir, string(t.generator.Output)); err != nil {
+			return errors.Format("%s: %w", msg, err)
+		}
+	}
+
+	return nil
+}
+
 type transformersTask struct {
 	taskParams
 	transformers []core.Transformer
@@ -422,7 +444,7 @@ func buildArtifact(ctx context.Context, idx int, artifact core.Artifact, tasks c
 	msg := fmt.Sprintf("could not build %s artifact %s", buildPlanName, artifact.Artifact)
 	// Process Generators concurrently
 	for gid, gen := range artifact.Generators {
-		task := generatorTask{
+		task := &generatorTask{
 			taskParams: taskParams{
 				taskName:      fmt.Sprintf("artifact/%d/generator/%d", idx, gid),
 				buildPlanName: buildPlanName,
@@ -480,11 +502,11 @@ func buildArtifact(ctx context.Context, idx int, artifact core.Artifact, tasks c
 
 	// Write the final artifact
 	out := string(artifact.Artifact)
-	if err := opts.Store.Save(opts.WriteTo, out); err != nil {
+	if err := opts.Store.Save(opts.AbsWriteTo(), out); err != nil {
 		return errors.Format("%s: %w", msg, err)
 	}
 	log := logger.FromContext(ctx)
-	log.DebugContext(ctx, fmt.Sprintf("wrote %s", filepath.Join(opts.WriteTo, out)))
+	log.DebugContext(ctx, fmt.Sprintf("wrote %s", filepath.Join(opts.AbsWriteTo(), out)))
 
 	return nil
 }
@@ -497,8 +519,10 @@ type BuildPlan struct {
 
 func (b *BuildPlan) Build(ctx context.Context) error {
 	name := b.BuildPlan.Metadata.Name
-	path := b.Opts.Path
-	log := logger.FromContext(ctx).With("name", name, "path", path)
+	log := logger.FromContext(ctx).With(
+		"name", name,
+		"path", filepath.Clean(b.Opts.Leaf()),
+	)
 
 	msg := fmt.Sprintf("could not build %s", name)
 	if b.BuildPlan.Spec.Disabled {
@@ -617,11 +641,11 @@ func commandTransformer(ctx context.Context, t core.Transformer, p taskParams) e
 		"could not transform %s for %s path %s",
 		t.Output,
 		p.buildPlanName,
-		p.opts.Path,
+		p.opts.Leaf(),
 	)
 
 	// Sanity checks.
-	tempDir := p.opts.BuildContext.TempDir
+	tempDir := p.opts.TempDir()
 	if tempDir == "" {
 		return errors.Format("%s: holos maintainer error: BuildContext.TempDir not provided by holos", msg)
 	}
@@ -666,7 +690,7 @@ func kustomize(ctx context.Context, t core.Transformer, p taskParams) error {
 		"could not transform %s for %s path %s",
 		t.Output,
 		p.buildPlanName,
-		p.opts.Path,
+		filepath.Clean(p.opts.Leaf()),
 	)
 
 	// Write the kustomization
@@ -701,6 +725,7 @@ func kustomize(ctx context.Context, t core.Transformer, p taskParams) error {
 	return nil
 }
 
+// TODO(jjm) move to transformerTask command
 func validate(ctx context.Context, validator core.Validator, p taskParams) error {
 	store := p.opts.Store
 	tempDir, err := os.MkdirTemp("", "holos.validate")
@@ -753,10 +778,10 @@ func (bc BuildContext) Tags() ([]string, error) {
 }
 
 // NewBuildContext returns a new BuildContext
-func NewBuildContext(bc holos.BuildContext) BuildContext {
+func NewBuildContext(tempDir string) BuildContext {
 	return BuildContext{
 		BuildContext: core.BuildContext{
-			TempDir: bc.TempDir,
+			TempDir: tempDir,
 		},
 	}
 }

internal/component/v1alpha6/v1alpha6_test.go

@@ -1,6 +1,7 @@
 package v1alpha6_test
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/holos-run/holos/internal/holos"
@@ -13,30 +14,51 @@ const apiVersion string = "v1alpha6"
 
 func TestComponents(t *testing.T) {
 	tempDir := testutil.SetupPlatform(t, apiVersion)
+	h := testutil.NewComponentHarness(t, tempDir, apiVersion)
+	root := h.Root()
+	assert.NotEmpty(t, root)
 
-	t.Run("Minimal", func(t *testing.T) {
-		msg := "Expected a minimal component to work, but do nothing"
-		h := testutil.NewComponentHarness(t, tempDir, apiVersion)
-		root := h.Root()
-		assert.NotEmpty(t, root)
+	t.Run("WithNoArtifacts", func(t *testing.T) {
+		leaf := "components/minimal"
+		c := h.Component(leaf)
+		msg := fmt.Sprintf("Expected %s with no artifacts to work, but do nothing", leaf)
 
-		componentPath := "components/minimal"
-		c := h.Component(componentPath)
+		tm, err := c.TypeMeta()
+		require.NoError(t, err, msg)
 
 		t.Run("TypeMeta", func(t *testing.T) {
-			tm, err := c.TypeMeta()
-			require.NoError(t, err, msg)
-			assert.Equal(t, apiVersion, tm.APIVersion)
-			assert.Equal(t, "BuildPlan", tm.Kind)
+			assert.Equal(t, apiVersion, tm.APIVersion, msg)
+			assert.Equal(t, "BuildPlan", tm.Kind, msg)
 		})
 
 		t.Run("BuildPlan", func(t *testing.T) {
-			tm, err := c.TypeMeta()
-			require.NoError(t, err, msg)
-			bp, err := c.BuildPlan(tm, holos.NewBuildOpts(componentPath))
+			bp, err := c.BuildPlan(tm, holos.NewBuildOpts(root, leaf, "deploy", t.TempDir()))
 			require.NoError(t, err, msg)
 			err = bp.Build(h.Ctx())
 			require.NoError(t, err, msg)
 		})
 	})
+
+	t.Run("BuildPlan", func(t *testing.T) {
+		t.Run("Command", func(t *testing.T) {
+			t.Run("Generator", func(t *testing.T) {
+				leaf := "components/commands/generator/simple"
+				c := h.Component(leaf)
+				msg := fmt.Sprintf("Expected %s with command generator to render config manifests", leaf)
+				tm, err := c.TypeMeta()
+				require.NoError(t, err, msg)
+				assert.Equal(t, tm.APIVersion, apiVersion)
+
+				t.Run("Build", func(t *testing.T) {
+					bp, err := c.BuildPlan(tm, holos.NewBuildOpts(root, leaf, "deploy", t.TempDir()))
+					require.NoError(t, err, msg)
+					err = bp.Build(h.Ctx())
+					require.NoError(t, err, msg)
+					// TODO: Check the rendered manifests.
+				})
+			})
+			t.Run("Transformer", func(t *testing.T) {})
+			t.Run("Validator", func(t *testing.T) {})
+		})
+	})
 }

internal/holos/types.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"runtime"
 	"strings"
 	"sync"
@@ -327,22 +328,54 @@ type BuildOpts struct {
 	// Tags represents user managed tags including a component name, labels, and
 	// annotations.
 	Tags []string
-	// BuildContext represents holos managed tags.
-	BuildContext BuildContext
+
+	root    string
+	leaf    string
+	writeTo string
+	tempDir string
 }
 
-// NewBuildOpts returns a [BuildOpts] configured to build the component at path.
-func NewBuildOpts(path string) BuildOpts {
+// NewBuildOpts returns a [BuildOpts] configured to build the component at leaf
+// from the platform module at root writing rendered manifests into the deploy
+// directory.
+func NewBuildOpts(root, leaf, deploy, tempDir string) BuildOpts {
 	return BuildOpts{
 		Store:       artifact.NewStore(),
 		Concurrency: min(runtime.NumCPU(), 8),
 		Stderr:      os.Stderr,
-		WriteTo:     "deploy",
-		Path:        path,
 		Tags:        make([]string, 0, 10),
+
+		root:    root,
+		leaf:    leaf,
+		writeTo: deploy,
+		tempDir: tempDir,
 	}
 }
 
+// Leaf returns the cleaned component path relative to the platform root. For
+// example "components/podinfo"
+func (b *BuildOpts) Leaf() string {
+	return filepath.Clean(b.leaf)
+}
+
+// TODO(jjm) rename to AbsLeaf() and document.
+func (b *BuildOpts) AbsPath() string {
+	return filepath.Join(b.root, b.leaf)
+}
+
+// AbsDeploy returns the absolute path to the write to directory, usually the
+// deploy sub directory of the platform module root.
+func (b *BuildOpts) AbsWriteTo() string {
+	return filepath.Join(b.root, b.writeTo)
+}
+
+// TempDir returns the temporary directory managed by holos and injected into
+// cue using a [BuildContext] so artifacts can refer to the same path in the
+// configuration.
+func (b *BuildOpts) TempDir() string {
+	return b.tempDir
+}
+
 // BuildContext represents build context values provided by the holos render
 // component command.  These values are expected to be randomly generated and
 // late binding, meaning they cannot be known ahead of time in a static

internal/testutil/fixtures/v1alpha6/components/commands/generator/simple/buildplan.cue

@@ -0,0 +1,33 @@
+package holos
+
+import (
+	"encoding/json"
+	"github.com/holos-run/holos/api/core/v1alpha6:core"
+)
+
+// Example of a simple v1alpha6 command generator.
+
+holos: core.#BuildPlan & {
+	metadata: {
+		name: "simple"
+		labels: "holos.run/component.name":       name
+		annotations: "app.holos.run/description": "\(name) command generator"
+	}
+	spec: artifacts: [{
+		artifact: "components/\(metadata.name)/\(metadata.name).gen.yaml"
+		generators: [{
+			kind:   "Command"
+			output: artifact
+			command: {
+				args: ["/bin/echo", json.Marshal(_ConfigMap)]
+				stdout: true
+			}
+		}]
+	}]
+}
+
+_ConfigMap: {
+	apiVersion: "v1"
+	kind:       "ConfigMap"
+	metadata: name: "simple"
+}

internal/testutil/fixtures/v1alpha6/components/commands/generator/simple/typemeta.cue

@@ -0,0 +1,16 @@
+@extern(embed)
+package holos
+
+import (
+	"encoding/json"
+	"github.com/holos-run/holos/api/core/v1alpha6:core"
+)
+
+_BuildContext: string | *"{}" @tag(holos_build_context, type=string)
+BuildContext:  core.#BuildContext & json.Unmarshal(_BuildContext)
+
+holos: core.#BuildPlan & {
+	buildContext: BuildContext
+}
+
+holos: _ @embed(file=typemeta.yaml)

internal/testutil/fixtures/v1alpha6/components/commands/generator/simple/typemeta.yaml

@@ -0,0 +1,2 @@
+kind: BuildPlan
+apiVersion: v1alpha6

internal/testutil/testutil.go

@@ -12,7 +12,7 @@ import (
 	"github.com/holos-run/holos/internal/component"
 	"github.com/holos-run/holos/internal/errors"
 	"github.com/holos-run/holos/internal/generate"
-	"gopkg.in/yaml.v2"
+	"gopkg.in/yaml.v3"
 )
 
 //go:embed all:fixtures