build: add support for configurable logging policies

docs/md/melange_build.md

@@ -44,6 +44,7 @@ melange build [flags]
       --guest-dir string            directory used for the build environment guest
   -h, --help                        help for build
   -k, --keyring-append strings      path to extra keys to include in the build environment keyring
+      --log-policy strings          logging policy to use (default [builtin:stderr])
       --namespace string            namespace to use in package URLs in SBOM (eg wolfi, alpine) (default "unknown")
       --out-dir string              directory where packages will be output (default "./packages/")
       --overlay-binsh string        use specified file as /bin/sh overlay in build environment

pkg/build/build.go

@@ -31,6 +31,7 @@ import (
 	apko_build "chainguard.dev/apko/pkg/build"
 	apko_oci "chainguard.dev/apko/pkg/build/oci"
 	apko_types "chainguard.dev/apko/pkg/build/types"
+	apko_iocomb "chainguard.dev/apko/pkg/iocomb"
 	apko_log "chainguard.dev/apko/pkg/log"
 	"k8s.io/kube-openapi/pkg/util/sets"
 
@@ -327,6 +328,7 @@ type Context struct {
 	imgDigest          name.Digest
 	containerConfig    *container.Config
 	Debug              bool
+	LogPolicy          []string
 
 	EnabledBuildOptions []string
 }
@@ -342,17 +344,13 @@ type Dependencies struct {
 var ErrSkipThisArch = errors.New("error: skip this arch")
 
 func New(opts ...Option) (*Context, error) {
-	logger := &apko_log.Adapter{
-		Out:   os.Stderr,
-		Level: apko_log.InfoLevel,
-	}
-
 	ctx := Context{
 		WorkspaceIgnore: ".melangeignore",
 		SourceDir:       ".",
 		OutDir:          ".",
 		CacheDir:        "./melange-cache/",
 		Arch:            apko_types.ParseArchitecture(runtime.GOARCH),
+		LogPolicy:       []string{"builtin:stderr"},
 	}
 
 	for _, opt := range opts {
@@ -361,6 +359,16 @@ func New(opts ...Option) (*Context, error) {
 		}
 	}
 
+	writer, err := apko_iocomb.Combine(ctx.LogPolicy)
+	if err != nil {
+		return nil, err
+	}
+
+	logger := &apko_log.Adapter{
+		Out:   writer,
+		Level: apko_log.InfoLevel,
+	}
+
 	fields := apko_log.Fields{
 		"arch": ctx.Arch.ToAPK(),
 	}
@@ -725,6 +733,14 @@ func WithDebug(debug bool) Option {
 	}
 }
 
+// WithLogPolicy sets the logging policy to use during builds.
+func WithLogPolicy(policy []string) Option {
+	return func(ctx *Context) error {
+		ctx.LogPolicy = policy
+		return nil
+	}
+}
+
 type ConfigurationParsingOption func(*configOptions)
 
 type configOptions struct {

pkg/cli/build.go

@@ -53,6 +53,7 @@ func Build() *cobra.Command {
 	var varsFile string
 	var purlNamespace string
 	var buildOption []string
+	var logPolicy []string
 	var createBuildLog bool
 	var debug bool
 
@@ -89,6 +90,7 @@ func Build() *cobra.Command {
 				build.WithEnabledBuildOptions(buildOption),
 				build.WithCreateBuildLog(createBuildLog),
 				build.WithDebug(debug),
+				build.WithLogPolicy(logPolicy),
 			}
 
 			if len(args) > 0 {
@@ -128,6 +130,7 @@ func Build() *cobra.Command {
 	cmd.Flags().StringVar(&purlNamespace, "namespace", "unknown", "namespace to use in package URLs in SBOM (eg wolfi, alpine)")
 	cmd.Flags().StringSliceVar(&archstrs, "arch", nil, "architectures to build for (e.g., x86_64,ppc64le,arm64) -- default is all, unless specified in config")
 	cmd.Flags().StringSliceVar(&buildOption, "build-option", []string{}, "build options to enable")
+	cmd.Flags().StringSliceVar(&logPolicy, "log-policy", []string{"builtin:stderr"}, "logging policy to use")
 	cmd.Flags().StringSliceVarP(&extraKeys, "keyring-append", "k", []string{}, "path to extra keys to include in the build environment keyring")
 	cmd.Flags().StringSliceVarP(&extraRepos, "repository-append", "r", []string{}, "path to extra repositories to include in the build environment")
 	cmd.Flags().BoolVar(&createBuildLog, "create-build-log", false, "creates a package.log file containing a list of packages that were built by the command")