Pass standard CI vars as build args into Docker/buildpack builds

Maps CodeBuild-specific env vars to neutral industry-standard names
and injects them into the build environment:
- CODEBUILD_WEBHOOK_HEAD_REF (or CODEBUILD_SOURCE_VERSION) → CI_COMMIT_REF
- CODEBUILD_RESOLVED_SOURCE_VERSION → CI_COMMIT_SHA
- CODEBUILD_START_TIME → CI_BUILD_STARTED_AT
- CODEBUILD_SOURCE_REPO_URL → CI_REPOSITORY_URL

Closes #13

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ipmb

builder/build/build.go

@@ -38,6 +38,11 @@ func (b *Build) LoadBuildEnv() (map[string]string, error) {
 	if val, ok := os.LookupEnv("ALLOW_EOL_SHIMMED_BUILDER"); ok {
 		env["ALLOW_EOL_SHIMMED_BUILDER"] = val
 	}
+	// map CodeBuild-specific vars to neutral CI vars and pass as build args
+	env["CI_COMMIT_REF"] = GetenvFallback([]string{"CODEBUILD_WEBHOOK_HEAD_REF", "CODEBUILD_SOURCE_VERSION"})
+	env["CI_COMMIT_SHA"] = os.Getenv("CODEBUILD_RESOLVED_SOURCE_VERSION")
+	env["CI_BUILD_STARTED_AT"] = os.Getenv("CODEBUILD_START_TIME")
+	env["CI_REPOSITORY_URL"] = os.Getenv("CODEBUILD_SOURCE_REPO_URL")
 	params, err := b.aws.GetParametersByPath(paths[0])
 	stripParamPrefix(params, paths[0], &env)
 	if err != nil {

builder/build/build_test.go

@@ -80,6 +80,71 @@ func TestLoadEnvInheritance(t *testing.T) {
 	}
 }
 
+func TestLoadBuildEnvCIVars(t *testing.T) {
+	appName := "test-app"
+	mockedAWS := new(MockAWS)
+	appConfigPrefix := fmt.Sprintf("/apppack/apps/%s/config/", appName)
+	mockedAWS.On("GetParametersByPath", appConfigPrefix).Return(map[string]string{}, nil)
+	mockedState := emptyState()
+	mockedState.On("ReadEnvFile").Return(&map[string]string{}, nil)
+
+	t.Setenv("CODEBUILD_WEBHOOK_HEAD_REF", "refs/heads/main")
+	t.Setenv("CODEBUILD_RESOLVED_SOURCE_VERSION", "deadbeef1234")
+	t.Setenv("CODEBUILD_START_TIME", "1234567890")
+	t.Setenv("CODEBUILD_SOURCE_REPO_URL", "https://github.com/org/repo")
+
+	b := Build{
+		Appname:          appName,
+		CodebuildBuildId: CodebuildBuildId,
+		aws:              mockedAWS,
+		state:            mockedState,
+		Ctx:              testContext,
+	}
+	env, err := b.LoadBuildEnv()
+	if err != nil {
+		t.Fatalf("expected no error, got %s", err)
+	}
+	if env["CI_COMMIT_REF"] != "refs/heads/main" {
+		t.Errorf("expected CI_COMMIT_REF=refs/heads/main, got %s", env["CI_COMMIT_REF"])
+	}
+	if env["CI_COMMIT_SHA"] != "deadbeef1234" {
+		t.Errorf("expected CI_COMMIT_SHA=deadbeef1234, got %s", env["CI_COMMIT_SHA"])
+	}
+	if env["CI_BUILD_STARTED_AT"] != "1234567890" {
+		t.Errorf("expected CI_BUILD_STARTED_AT=1234567890, got %s", env["CI_BUILD_STARTED_AT"])
+	}
+	if env["CI_REPOSITORY_URL"] != "https://github.com/org/repo" {
+		t.Errorf("expected CI_REPOSITORY_URL=https://github.com/org/repo, got %s", env["CI_REPOSITORY_URL"])
+	}
+}
+
+func TestLoadBuildEnvCIVarsFallback(t *testing.T) {
+	// When CODEBUILD_WEBHOOK_HEAD_REF is not set, CI_COMMIT_REF should fall back to CODEBUILD_SOURCE_VERSION
+	appName := "test-app"
+	mockedAWS := new(MockAWS)
+	appConfigPrefix := fmt.Sprintf("/apppack/apps/%s/config/", appName)
+	mockedAWS.On("GetParametersByPath", appConfigPrefix).Return(map[string]string{}, nil)
+	mockedState := emptyState()
+	mockedState.On("ReadEnvFile").Return(&map[string]string{}, nil)
+
+	t.Setenv("CODEBUILD_SOURCE_VERSION", "refs/heads/feature-branch")
+
+	b := Build{
+		Appname:          appName,
+		CodebuildBuildId: CodebuildBuildId,
+		aws:              mockedAWS,
+		state:            mockedState,
+		Ctx:              testContext,
+	}
+	env, err := b.LoadBuildEnv()
+	if err != nil {
+		t.Fatalf("expected no error, got %s", err)
+	}
+	if env["CI_COMMIT_REF"] != "refs/heads/feature-branch" {
+		t.Errorf("expected CI_COMMIT_REF=refs/heads/feature-branch, got %s", env["CI_COMMIT_REF"])
+	}
+}
+
 func TestGenerateDockerEnvStrings(t *testing.T) {
 	env := map[string]string{
 		"FOO": "bar",