Base Configs Support - Phase 1

toolkit/tools/imagecustomizerapi/baseconfig.go

@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package imagecustomizerapi
+
+import (
+	"fmt"
+	"strings"
+)
+
+type BaseConfig struct {
+	Path string `yaml:"path" json:"path"`
+}
+
+func (b BaseConfig) IsValid() error {
+	if strings.TrimSpace(b.Path) == "" {
+		return fmt.Errorf("path must not be empty or whitespace")
+	}
+	return nil
+}

toolkit/tools/imagecustomizerapi/config.go

@@ -19,6 +19,7 @@ type Config struct {
 	Scripts         Scripts          `yaml:"scripts" json:"scripts,omitempty"`
 	PreviewFeatures []PreviewFeature `yaml:"previewFeatures" json:"previewFeatures,omitempty"`
 	Output          Output           `yaml:"output" json:"output,omitempty"`
+	BaseConfigs     []BaseConfig     `yaml:"baseConfigs" json:"baseConfigs,omitempty"`
 }
 
 func (c *Config) IsValid() (err error) {
@@ -123,6 +124,18 @@ func (c *Config) IsValid() (err error) {
 		return fmt.Errorf("the 'reinitialize-verity' preview feature must be enabled to use 'storage.reinitializeVerity'")
 	}
 
+	if c.BaseConfigs != nil {
+		if !sliceutils.ContainsValue(c.PreviewFeatures, PreviewFeatureBaseConfigs) {
+			return fmt.Errorf("the '%s' preview feature must be enabled to use 'baseConfigs'", PreviewFeatureBaseConfigs)
+		}
+
+		for i, base := range c.BaseConfigs {
+			if err := base.IsValid(); err != nil {
+				return fmt.Errorf("invalid baseConfig item at index %d:\n%w", i, err)
+			}
+		}
+	}
+
 	return nil
 }
 

toolkit/tools/imagecustomizerapi/previewfeaturetype.go

@@ -28,12 +28,15 @@ const (
 
 	// PreviewFeatureFedora42 enables support for Fedora 42 images.
 	PreviewFeatureFedora42 PreviewFeature = "fedora-42"
+
+	// PreviewFeatureBaseConfigs enables support for base configuration.
+	PreviewFeatureBaseConfigs PreviewFeature = "base-configs"
 )
 
 func (pf PreviewFeature) IsValid() error {
 	switch pf {
 	case PreviewFeatureUki, PreviewFeatureOutputArtifacts, PreviewFeatureInjectFiles, PreviewFeaturePackageSnapshotTime,
-		PreviewFeatureKdumpBootFiles, PreviewFeatureFedora42:
+		PreviewFeatureKdumpBootFiles, PreviewFeatureFedora42, PreviewFeatureBaseConfigs:
 		return nil
 	default:
 		return fmt.Errorf("invalid preview feature: %s", pf)

toolkit/tools/imagecustomizerapi/schema.json

@@ -45,6 +45,15 @@
       "additionalProperties": false,
       "type": "object"
     },
+    "BaseConfig": {
+      "properties": {
+        "path": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object"
+    },
     "BootLoader": {
       "properties": {
         "resetType": {
@@ -82,6 +91,12 @@
         },
         "output": {
           "$ref": "#/$defs/Output"
+        },
+        "baseConfigs": {
+          "items": {
+            "$ref": "#/$defs/BaseConfig"
+          },
+          "type": "array"
         }
       },
       "additionalProperties": false,

toolkit/tools/pkg/imagecustomizerlib/baseconfigs.go

@@ -0,0 +1,169 @@
+package imagecustomizerlib
+
+import (
+	"context"
+	"fmt"
+
+	"path/filepath"
+
+	"github.com/microsoft/azure-linux-image-tools/toolkit/tools/imagecustomizerapi"
+)
+
+func ResolveBaseConfigs(ctx context.Context, rc *ResolvedConfig) error {
+	visited := make(map[string]bool)
+	pathStack := []string{}
+
+	configChain, err := BuildInheritanceChain(ctx, rc.Config, rc.BaseConfigPath, visited, pathStack)
+	if err != nil {
+		return err
+	}
+
+	merged := &ResolvedConfig{}
+
+	resolveOverrideFields(configChain, merged)
+	resolveMergeFields(configChain, merged)
+
+	if merged.Config.Input != (imagecustomizerapi.Input{}) {
+		rc.Config.Input = merged.Config.Input
+	}
+	if merged.Config.Output != (imagecustomizerapi.Output{}) {
+		rc.Config.Output = merged.Config.Output
+	}
+
+	return nil
+}
+
+func BuildInheritanceChain(ctx context.Context, cfg *imagecustomizerapi.Config, baseDir string, visited map[string]bool, pathStack []string) ([]*imagecustomizerapi.Config, error) {
+	if cfg.BaseConfigs != nil {
+		for i, base := range cfg.BaseConfigs {
+			err := base.IsValid()
+			if err != nil {
+				return nil, fmt.Errorf("invalid baseConfig item at index %d:\n%w", i, err)
+			}
+		}
+	}
+
+	var chain []*imagecustomizerapi.Config
+
+	for _, base := range cfg.BaseConfigs {
+		basePath := filepath.Join(baseDir, base.Path)
+		absPath, err := filepath.Abs(basePath)
+		if err != nil {
+			return nil, err
+		}
+
+		if visited[absPath] {
+			return nil, fmt.Errorf("cycle detected in baseConfigs: %v -> %s", pathStack, absPath)
+		}
+
+		visited[absPath] = true
+		pathStack = append(pathStack, absPath)
+
+		// Load base file into struct
+		var baseCfg imagecustomizerapi.Config
+		if err := imagecustomizerapi.UnmarshalYamlFile(absPath, &baseCfg); err != nil {
+			return nil, fmt.Errorf("failed to load base config %s: %w", absPath, err)
+		}
+
+		// Validate base config content
+		if err := baseCfg.IsValid(); err != nil {
+			return nil, fmt.Errorf("%w at %s:\n%v", ErrInvalidImageConfig, absPath, err)
+		}
+
+		// Recurse into base config
+		subChain, err := BuildInheritanceChain(ctx, &baseCfg, filepath.Dir(absPath), visited, pathStack)
+		if err != nil {
+			return nil, err
+		}
+
+		chain = append(chain, subChain...)
+	}
+
+	// Add the current config at the end
+	chain = append(chain, cfg)
+
+	return chain, nil
+}
+
+func resolveOverrideFields(chain []*imagecustomizerapi.Config, target *ResolvedConfig) {
+	// Defensive initialization to avoid nil dereference
+	if target.Config == nil {
+		target.Config = &imagecustomizerapi.Config{}
+	}
+	if target.Config.Input.Image == (imagecustomizerapi.InputImage{}) {
+		target.Config.Input = imagecustomizerapi.Input{}
+	}
+	if target.Config.Output == (imagecustomizerapi.Output{}) {
+		target.Config.Output = imagecustomizerapi.Output{}
+	}
+
+	for _, config := range chain {
+		// .input.image.path
+		if config.Input.Image.Path != "" {
+			target.Config.Input.Image.Path = config.Input.Image.Path
+		}
+
+		// .output.image.path
+		if config.Output.Image.Path != "" {
+			target.Config.Output.Image.Path = config.Output.Image.Path
+		}
+
+		// .output.image.format
+		if config.Output.Image.Format != "" {
+			target.Config.Output.Image.Format = config.Output.Image.Format
+		}
+
+		// .output.artifacts.path
+		if config.Output.Artifacts != nil {
+			if target.Config.Output.Artifacts == nil {
+				target.Config.Output.Artifacts = &imagecustomizerapi.Artifacts{}
+			}
+			if config.Output.Artifacts.Path != "" {
+				target.Config.Output.Artifacts.Path = config.Output.Artifacts.Path
+			}
+		}
+
+	}
+}
+
+func resolveMergeFields(chain []*imagecustomizerapi.Config, target *ResolvedConfig) {
+	// Defensive initialization
+	if target.Config.Output == (imagecustomizerapi.Output{}) {
+		target.Config.Output = imagecustomizerapi.Output{}
+	}
+
+	for _, config := range chain {
+		if config.Output.Artifacts != nil {
+			if target.Config.Output.Artifacts == nil {
+				target.Config.Output.Artifacts = &imagecustomizerapi.Artifacts{}
+			}
+			target.Config.Output.Artifacts.Items = mergeOutputArtifactTypes(
+				target.Config.Output.Artifacts.Items,
+				config.Output.Artifacts.Items,
+			)
+		}
+	}
+}
+
+func mergeOutputArtifactTypes(base, current []imagecustomizerapi.OutputArtifactsItemType) []imagecustomizerapi.OutputArtifactsItemType {
+	seen := make(map[imagecustomizerapi.OutputArtifactsItemType]bool)
+	var merged []imagecustomizerapi.OutputArtifactsItemType
+
+	// Add base items first
+	for _, item := range base {
+		if !seen[item] {
+			merged = append(merged, item)
+			seen[item] = true
+		}
+	}
+
+	// Add current items
+	for _, item := range current {
+		if !seen[item] {
+			merged = append(merged, item)
+			seen[item] = true
+		}
+	}
+
+	return merged
+}

toolkit/tools/pkg/imagecustomizerlib/baseconfigs_test.go

@@ -0,0 +1,87 @@
+package imagecustomizerlib
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/microsoft/azure-linux-image-tools/toolkit/tools/imagecustomizerapi"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBaseConfigsInputAndOutput(t *testing.T) {
+	testTempDir := filepath.Join(tmpDir, "TestBaseConfigsInputAndOutput")
+	defer os.RemoveAll(testTempDir)
+
+	buildDir := filepath.Join(testTempDir, "build")
+	currentConfigFile := filepath.Join(testDir, "current-config.yaml")
+
+	options := ImageCustomizerOptions{
+		BuildDir:       buildDir,
+		InputImageFile: currentConfigFile,
+	}
+
+	var config imagecustomizerapi.Config
+	err := imagecustomizerapi.UnmarshalYamlFile(currentConfigFile, &config)
+	assert.NoError(t, err)
+
+	baseConfigPath, _ := filepath.Split(currentConfigFile)
+	absBaseConfigPath, err := filepath.Abs(baseConfigPath)
+	assert.NoError(t, err)
+
+	rc := &ResolvedConfig{
+		BaseConfigPath: absBaseConfigPath,
+		Config:         &config,
+		Options:        options,
+	}
+
+	err = ResolveBaseConfigs(t.Context(), rc)
+	assert.NoError(t, err)
+
+	assert.Equal(t, ".testimages/input-image-2.vhdx", rc.Config.Input.Image.Path)
+	assert.Equal(t, "./out/output-image-2.vhdx", rc.Config.Output.Image.Path)
+	assert.Equal(t, "./artifacts-2", rc.Config.Output.Artifacts.Path)
+	assert.Equal(t, "testname", rc.Config.OS.Hostname)
+
+	expectedItems := []imagecustomizerapi.OutputArtifactsItemType{
+		imagecustomizerapi.OutputArtifactsItemUkis,
+		imagecustomizerapi.OutputArtifactsItemShim,
+	}
+	actual := rc.Config.Output.Artifacts.Items
+	assert.Equal(t, len(expectedItems), len(actual))
+
+	for _, item := range expectedItems {
+		assert.Containsf(t, actual, item, "expected output artifact item %q not found in resolved config: %v", item, actual)
+	}
+}
+
+func TestBaseConfigsMalformed(t *testing.T) {
+	testTempDir := filepath.Join(tmpDir, "TestBaseConfigsMalformed")
+	defer os.RemoveAll(testTempDir)
+
+	buildDir := filepath.Join(testTempDir, "build")
+	currentConfigFile := filepath.Join(testDir, "current-config-malformed.yaml")
+
+	options := ImageCustomizerOptions{
+		BuildDir:       buildDir,
+		InputImageFile: currentConfigFile,
+	}
+
+	var config imagecustomizerapi.Config
+	err := imagecustomizerapi.UnmarshalYamlFile(currentConfigFile, &config)
+	assert.NoError(t, err)
+
+	baseConfigPath, _ := filepath.Split(currentConfigFile)
+	absBaseConfigPath, err := filepath.Abs(baseConfigPath)
+	assert.NoError(t, err)
+
+	rc := &ResolvedConfig{
+		BaseConfigPath: absBaseConfigPath,
+		Config:         &config,
+		Options:        options,
+	}
+
+	err = ResolveBaseConfigs(t.Context(), rc)
+
+	assert.ErrorContains(t, err, ErrInvalidImageConfig.Error())
+}

toolkit/tools/pkg/imagecustomizerlib/configvalidation.go

@@ -54,6 +54,8 @@ func ValidateConfig(ctx context.Context, baseConfigPath string, config *imagecus
 		Options:        options,
 	}
 
+	ResolveBaseConfigs(ctx, rc)
+
 	err := options.IsValid()
 	if err != nil {
 		return nil, err