move iocomb into pkg/log

Signed-off-by: Jason Hall <jason@chainguard.dev>

internal/cli/commands.go

@@ -20,7 +20,7 @@ import (
 	"net/http"
 	"os"
 
-	"chainguard.dev/apko/internal/iocomb"
+	alog "chainguard.dev/apko/pkg/log"
 	cranecmd "github.com/google/go-containerregistry/cmd/crane/cmd"
 	"github.com/spf13/cobra"
 	"sigs.k8s.io/release-utils/version"
@@ -44,7 +44,7 @@ func New() *cobra.Command {
 					return fmt.Errorf("failed to change dir to %s: %w", workDir, err)
 				}
 			}
-			out, err := iocomb.Combine(logPolicy)
+			out, err := alog.Writer(logPolicy)
 			if err != nil {
 				return fmt.Errorf("failed to initialize logging: %w", err)
 			}

pkg/log/log.go

@@ -17,9 +17,13 @@ package log
 import (
 	"context"
 	"fmt"
+	"io"
 	"log"
 	"log/slog"
+	"os"
+	"path/filepath"
 	"runtime"
+	"strings"
 	"time"
 )
 
@@ -29,6 +33,8 @@ func Warnf(format string, args ...interface{})  { wrap(slog.LevelWarn, format, a
 func Errorf(format string, args ...interface{}) { wrap(slog.LevelError, format, args...) }
 func Fatalf(format string, args ...interface{}) { log.Fatal(fmt.Sprintf(format, args...)) }
 
+func Printf(format string, args ...interface{}) { wrap(slog.LevelInfo, format, args...) }
+
 // https://pkg.go.dev/log/slog#hdr-Writing_a_handler
 func wrap(level slog.Level, format string, args ...interface{}) {
 	ctx := context.Background()
@@ -42,3 +48,49 @@ func wrap(level slog.Level, format string, args ...interface{}) {
 	_ = l.Handler().Handle(ctx, r)
 }
 
+// writerFromTarget returns a writer given a target specification.
+func writerFromTarget(target string) (io.Writer, error) {
+	switch target {
+	case "builtin:stderr":
+		return os.Stderr, nil
+	case "builtin:stdout":
+		return os.Stdout, nil
+	case "builtin:discard":
+		return io.Discard, nil
+	default:
+		if strings.Contains(target, "/") {
+			parent := filepath.Dir(target)
+			if err := os.MkdirAll(parent, 0o755); err != nil {
+				return nil, err
+			}
+		}
+
+		log.Println("writing log file to", target)
+		out, err := os.OpenFile(target, os.O_RDWR|os.O_CREATE, 0o644)
+		if err != nil {
+			return nil, err
+		}
+
+		return out, nil
+	}
+}
+
+// Writer returns a writer which writes to multiple target specifications.
+func Writer(targets []string) (io.Writer, error) {
+	writers := []io.Writer{}
+
+	if len(targets) == 1 {
+		return writerFromTarget(targets[0])
+	}
+
+	for _, target := range targets {
+		writer, err := writerFromTarget(target)
+		if err != nil {
+			return nil, err
+		}
+
+		writers = append(writers, writer)
+	}
+
+	return io.MultiWriter(writers...), nil
+}