PythonMutator: replace stdin/stdout with files (#1512)

## Changes
Replace stdin/stdout with files in `PythonMutator`. Files are created in
a temporary directory.

Rename `ApplyPythonMutator` to `PythonMutator`.

Add test for `dyn.Location` behavior during the "load" stage.

## Tests
Unit tests

bundle/config/mutator/mutator.go

@@ -25,6 +25,6 @@ func DefaultMutators() []bundle.Mutator {
 		InitializeVariables(),
 		DefineDefaultTarget(),
 		LoadGitDetails(),
-		pythonmutator.ApplyPythonMutator(pythonmutator.ApplyPythonMutatorPhaseLoad),
+		pythonmutator.PythonMutator(pythonmutator.PythonMutatorPhaseLoad),
 	}
 }

bundle/config/mutator/python/apply_python_mutator.go → bundle/config/mutator/python/python_mutator.go

@@ -1,14 +1,15 @@
 package python
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"runtime"
 
+	"github.com/databricks/cli/bundle/env"
+
 	"github.com/databricks/cli/bundle"
 	"github.com/databricks/cli/bundle/config"
 	"github.com/databricks/cli/libs/diag"
@@ -23,17 +24,17 @@ import (
 type phase string
 
 const (
-	// ApplyPythonMutatorPhaseLoad is the phase in which bundle configuration is loaded.
+	// PythonMutatorPhaseLoad is the phase in which bundle configuration is loaded.
 	//
 	// At this stage, PyDABs adds statically defined resources to the bundle configuration.
 	// Which resources are added should be deterministic and not depend on the bundle configuration.
 	//
 	// We also open for possibility of appending other sections of bundle configuration,
 	// for example, adding new variables. However, this is not supported yet, and CLI rejects
 	// such changes.
-	ApplyPythonMutatorPhaseLoad phase = "load"
+	PythonMutatorPhaseLoad phase = "load"
 
-	// ApplyPythonMutatorPhaseInit is the phase after bundle configuration was loaded, and
+	// PythonMutatorPhaseInit is the phase after bundle configuration was loaded, and
 	// the list of statically declared resources is known.
 	//
 	// At this stage, PyDABs adds resources defined using generators, or mutates existing resources,
@@ -50,21 +51,21 @@ const (
 	// PyDABs can output YAML containing references to variables, and CLI should resolve them.
 	//
 	// Existing resources can't be removed, and CLI rejects such changes.
-	ApplyPythonMutatorPhaseInit phase = "init"
+	PythonMutatorPhaseInit phase = "init"
 )
 
-type applyPythonMutator struct {
+type pythonMutator struct {
 	phase phase
 }
 
-func ApplyPythonMutator(phase phase) bundle.Mutator {
-	return &applyPythonMutator{
+func PythonMutator(phase phase) bundle.Mutator {
+	return &pythonMutator{
 		phase: phase,
 	}
 }
 
-func (m *applyPythonMutator) Name() string {
-	return fmt.Sprintf("ApplyPythonMutator(%s)", m.phase)
+func (m *pythonMutator) Name() string {
+	return fmt.Sprintf("PythonMutator(%s)", m.phase)
 }
 
 func getExperimental(b *bundle.Bundle) config.Experimental {
@@ -75,7 +76,7 @@ func getExperimental(b *bundle.Bundle) config.Experimental {
 	return *b.Config.Experimental
 }
 
-func (m *applyPythonMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostics {
+func (m *pythonMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostics {
 	experimental := getExperimental(b)
 
 	if !experimental.PyDABs.Enabled {
@@ -97,7 +98,12 @@ func (m *applyPythonMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.D
 			}
 		}
 
-		rightRoot, err := m.runPythonMutator(ctx, b.RootPath, pythonPath, leftRoot)
+		cacheDir, err := createCacheDir(ctx)
+		if err != nil {
+			return dyn.InvalidValue, fmt.Errorf("failed to create cache dir: %w", err)
+		}
+
+		rightRoot, err := m.runPythonMutator(ctx, cacheDir, b.RootPath, pythonPath, leftRoot)
 		if err != nil {
 			return dyn.InvalidValue, err
 		}
@@ -113,13 +119,39 @@ func (m *applyPythonMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.D
 	return diag.FromErr(err)
 }
 
-func (m *applyPythonMutator) runPythonMutator(ctx context.Context, rootPath string, pythonPath string, root dyn.Value) (dyn.Value, error) {
+func createCacheDir(ctx context.Context) (string, error) {
+	// b.CacheDir doesn't work because target isn't yet selected
+
+	// support the same env variable as in b.CacheDir
+	if tempDir, exists := env.TempDir(ctx); exists {
+		// use 'default' as target name
+		cacheDir := filepath.Join(tempDir, "default", "pydabs")
+
+		err := os.MkdirAll(cacheDir, 0700)
+		if err != nil {
+			return "", err
+		}
+
+		return cacheDir, nil
+	}
+
+	return os.MkdirTemp("", "-pydabs")
+}
+
+func (m *pythonMutator) runPythonMutator(ctx context.Context, cacheDir string, rootPath string, pythonPath string, root dyn.Value) (dyn.Value, error) {
+	inputPath := filepath.Join(cacheDir, "input.json")
+	outputPath := filepath.Join(cacheDir, "output.json")
+
 	args := []string{
 		pythonPath,
 		"-m",
 		"databricks.bundles.build",
 		"--phase",
 		string(m.phase),
+		"--input",
+		inputPath,
+		"--output",
+		outputPath,
 	}
 
 	// we need to marshal dyn.Value instead of bundle.Config to JSON to support
@@ -129,27 +161,48 @@ func (m *applyPythonMutator) runPythonMutator(ctx context.Context, rootPath stri
 		return dyn.InvalidValue, fmt.Errorf("failed to marshal root config: %w", err)
 	}
 
-	logWriter := newLogWriter(ctx, "stderr: ")
+	err = os.WriteFile(inputPath, rootConfigJson, 0600)
+	if err != nil {
+		return dyn.InvalidValue, fmt.Errorf("failed to write input file: %w", err)
+	}
+
+	stderrWriter := newLogWriter(ctx, "stderr: ")
+	stdoutWriter := newLogWriter(ctx, "stdout: ")
 
-	stdout, err := process.Background(
+	_, err = process.Background(
 		ctx,
 		args,
 		process.WithDir(rootPath),
-		process.WithStderrWriter(logWriter),
-		process.WithStdinReader(bytes.NewBuffer(rootConfigJson)),
+		process.WithStderrWriter(stderrWriter),
+		process.WithStdoutWriter(stdoutWriter),
 	)
 	if err != nil {
 		return dyn.InvalidValue, fmt.Errorf("python mutator process failed: %w", err)
 	}
 
-	// we need absolute path, or because later parts of pipeline assume all paths are absolute
-	// and this file will be used as location
+	outputFile, err := os.Open(outputPath)
+	if err != nil {
+		return dyn.InvalidValue, fmt.Errorf("failed to open Python mutator output: %w", err)
+	}
+
+	defer func() {
+		_ = outputFile.Close()
+	}()
+
+	// we need absolute path because later parts of pipeline assume all paths are absolute
+	// and this file will be used as location to resolve relative paths.
+	//
+	// virtualPath has to stay in rootPath, because locations outside root path are not allowed:
+	//
+	//   Error: path /var/folders/.../pydabs/dist/*.whl is not contained in bundle root path
+	//
+	// for that, we pass virtualPath instead of outputPath as file location
 	virtualPath, err := filepath.Abs(filepath.Join(rootPath, "__generated_by_pydabs__.yml"))
 	if err != nil {
 		return dyn.InvalidValue, fmt.Errorf("failed to get absolute path: %w", err)
 	}
 
-	generated, err := yamlloader.LoadYAML(virtualPath, bytes.NewReader([]byte(stdout)))
+	generated, err := yamlloader.LoadYAML(virtualPath, outputFile)
 	if err != nil {
 		return dyn.InvalidValue, fmt.Errorf("failed to parse Python mutator output: %w", err)
 	}
@@ -171,9 +224,9 @@ func (m *applyPythonMutator) runPythonMutator(ctx context.Context, rootPath stri
 
 func createOverrideVisitor(ctx context.Context, phase phase) (merge.OverrideVisitor, error) {
 	switch phase {
-	case ApplyPythonMutatorPhaseLoad:
+	case PythonMutatorPhaseLoad:
 		return createLoadOverrideVisitor(ctx), nil
-	case ApplyPythonMutatorPhaseInit:
+	case PythonMutatorPhaseInit:
 		return createInitOverrideVisitor(ctx), nil
 	default:
 		return merge.OverrideVisitor{}, fmt.Errorf("unknown phase: %s", phase)