Use cobra's RunE whenever possible (#988)

cmd/crane/cmd/append.go

@@ -15,7 +15,7 @@
 package cmd
 
 import (
-	"log"
+	"fmt"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/google/go-containerregistry/pkg/logs"
@@ -33,35 +33,35 @@ func NewCmdAppend(options *[]crane.Option) *cobra.Command {
 		Use:   "append",
 		Short: "Append contents of a tarball to a remote image",
 		Args:  cobra.NoArgs,
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			var base v1.Image
 			var err error
 
 			if baseRef == "" {
 				logs.Warn.Printf("base unspecified, using empty image")
 				base = empty.Image
-
 			} else {
 				base, err = crane.Pull(baseRef, *options...)
 				if err != nil {
-					log.Fatalf("pulling %s: %v", baseRef, err)
+					return fmt.Errorf("pulling %s: %v", baseRef, err)
 				}
 			}
 
 			img, err := crane.Append(base, newLayers...)
 			if err != nil {
-				log.Fatalf("appending %v: %v", newLayers, err)
+				return fmt.Errorf("appending %v: %v", newLayers, err)
 			}
 
 			if outFile != "" {
 				if err := crane.Save(img, newTag, outFile); err != nil {
-					log.Fatalf("writing output %q: %v", outFile, err)
+					return fmt.Errorf("writing output %q: %v", outFile, err)
 				}
 			} else {
 				if err := crane.Push(img, newTag, *options...); err != nil {
-					log.Fatalf("pushing image %s: %v", newTag, err)
+					return fmt.Errorf("pushing image %s: %v", newTag, err)
 				}
 			}
+			return nil
 		},
 	}
 	appendCmd.Flags().StringVarP(&baseRef, "base", "b", "", "Name of base image to append to")

cmd/crane/cmd/auth.go

@@ -78,18 +78,18 @@ func NewCmdAuthGet(argv ...string) *cobra.Command {
 		Short:   "Implements a credential helper",
 		Example: eg,
 		Args:    cobra.NoArgs,
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			b, err := ioutil.ReadAll(os.Stdin)
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 			reg, err := name.NewRegistry(strings.TrimSpace(string(b)))
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 			authorizer, err := authn.DefaultKeychain.Resolve(reg)
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 
 			// If we don't find any credentials, there's a magic error to return:
@@ -103,15 +103,13 @@ func NewCmdAuthGet(argv ...string) *cobra.Command {
 
 			auth, err := authorizer.Authorization()
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 
 			// Convert back to a form that credential helpers can parse so that this
 			// can act as a meta credential helper.
 			creds := toCreds(auth)
-			if err := json.NewEncoder(os.Stdout).Encode(creds); err != nil {
-				log.Fatal(err)
-			}
+			return json.NewEncoder(os.Stdout).Encode(creds)
 		},
 	}
 }
@@ -132,17 +130,15 @@ func NewCmdAuthLogin(argv ...string) *cobra.Command {
 		Short:   "Log in to a registry",
 		Example: eg,
 		Args:    cobra.ExactArgs(1),
-		Run: func(cmd *cobra.Command, args []string) {
+		RunE: func(cmd *cobra.Command, args []string) error {
 			reg, err := name.NewRegistry(args[0])
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 
 			opts.serverAddress = reg.Name()
 
-			if err := login(opts); err != nil {
-				log.Fatal(err)
-			}
+			return login(opts)
 		},
 	}
 

cmd/crane/cmd/blob.go

@@ -15,8 +15,8 @@
 package cmd
 
 import (
+	"fmt"
 	"io"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -29,19 +29,20 @@ func NewCmdBlob(options *[]crane.Option) *cobra.Command {
 		Short:   "Read a blob from the registry",
 		Example: "crane blob ubuntu@sha256:4c1d20cdee96111c8acf1858b62655a37ce81ae48648993542b7ac363ac5c0e5 > blob.tar.gz",
 		Args:    cobra.ExactArgs(1),
-		Run: func(cmd *cobra.Command, args []string) {
+		RunE: func(cmd *cobra.Command, args []string) error {
 			src := args[0]
 			layer, err := crane.PullLayer(src, *options...)
 			if err != nil {
-				log.Fatalf("pulling layer %s: %v", src, err)
+				return fmt.Errorf("pulling layer %s: %v", src, err)
 			}
 			blob, err := layer.Compressed()
 			if err != nil {
-				log.Fatalf("fetching blob %s: %v", src, err)
+				return fmt.Errorf("fetching blob %s: %v", src, err)
 			}
 			if _, err := io.Copy(cmd.OutOrStdout(), blob); err != nil {
-				log.Fatalf("copying blob %s: %v", src, err)
+				return fmt.Errorf("copying blob %s: %v", src, err)
 			}
+			return nil
 		},
 	}
 }

cmd/crane/cmd/catalog.go

@@ -16,7 +16,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -28,16 +27,17 @@ func NewCmdCatalog(options *[]crane.Option) *cobra.Command {
 		Use:   "catalog",
 		Short: "List the repos in a registry",
 		Args:  cobra.ExactArgs(1),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			reg := args[0]
 			repos, err := crane.Catalog(reg, *options...)
 			if err != nil {
-				log.Fatalf("reading repos for %s: %v", reg, err)
+				return fmt.Errorf("reading repos for %s: %v", reg, err)
 			}
 
 			for _, repo := range repos {
 				fmt.Println(repo)
 			}
+			return nil
 		},
 	}
 }

cmd/crane/cmd/config.go

@@ -16,7 +16,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -28,12 +27,13 @@ func NewCmdConfig(options *[]crane.Option) *cobra.Command {
 		Use:   "config IMAGE",
 		Short: "Get the config of an image",
 		Args:  cobra.ExactArgs(1),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			cfg, err := crane.Config(args[0], *options...)
 			if err != nil {
-				log.Fatalf("fetching config: %v", err)
+				return fmt.Errorf("fetching config: %v", err)
 			}
 			fmt.Print(string(cfg))
+			return nil
 		},
 	}
 }

cmd/crane/cmd/copy.go

@@ -15,8 +15,6 @@
 package cmd
 
 import (
-	"log"
-
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
 )
@@ -28,11 +26,9 @@ func NewCmdCopy(options *[]crane.Option) *cobra.Command {
 		Aliases: []string{"cp"},
 		Short:   "Efficiently copy a remote image from src to dst",
 		Args:    cobra.ExactArgs(2),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			src, dst := args[0], args[1]
-			if err := crane.Copy(src, dst, *options...); err != nil {
-				log.Fatal(err)
-			}
+			return crane.Copy(src, dst, *options...)
 		},
 	}
 }

cmd/crane/cmd/delete.go

@@ -15,8 +15,6 @@
 package cmd
 
 import (
-	"log"
-
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
 )
@@ -27,11 +25,9 @@ func NewCmdDelete(options *[]crane.Option) *cobra.Command {
 		Use:   "delete IMAGE",
 		Short: "Delete an image reference from its registry",
 		Args:  cobra.ExactArgs(1),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			ref := args[0]
-			if err := crane.Delete(ref, *options...); err != nil {
-				log.Fatalf("deleting %s: %v", ref, err)
-			}
+			return crane.Delete(ref, *options...)
 		},
 	}
 }

cmd/crane/cmd/digest.go

@@ -15,8 +15,8 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -29,17 +29,18 @@ func NewCmdDigest(options *[]crane.Option) *cobra.Command {
 		Use:   "digest IMAGE",
 		Short: "Get the digest of an image",
 		Args:  cobra.MaximumNArgs(1),
-		Run: func(cmd *cobra.Command, args []string) {
+		RunE: func(cmd *cobra.Command, args []string) error {
 			if tarball == "" && len(args) == 0 {
 				cmd.Help()
-				log.Fatalf("image reference required without --tarball")
+				return errors.New("image reference required without --tarball")
 			}
 
 			digest, err := getDigest(tarball, args, options)
 			if err != nil {
-				log.Fatal(err)
+				return err
 			}
 			fmt.Println(digest)
+			return nil
 		},
 	}
 

cmd/crane/cmd/export.go

@@ -15,7 +15,7 @@
 package cmd
 
 import (
-	"log"
+	"fmt"
 	"os"
 
 	"github.com/google/go-containerregistry/pkg/crane"
@@ -33,23 +33,21 @@ func NewCmdExport(options *[]crane.Option) *cobra.Command {
   # Write tarball to file
   crane export ubuntu ubuntu.tar`,
 		Args: cobra.ExactArgs(2),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			src, dst := args[0], args[1]
 
 			f, err := openFile(dst)
 			if err != nil {
-				log.Fatalf("failed to open %s: %v", dst, err)
+				return fmt.Errorf("failed to open %s: %v", dst, err)
 			}
 			defer f.Close()
 
 			img, err := crane.Pull(src, *options...)
 			if err != nil {
-				log.Fatal(err)
+				return fmt.Errorf("pulling %s: %v", src, err)
 			}
 
-			if err := crane.Export(img, f); err != nil {
-				log.Fatalf("exporting %s: %v", src, err)
-			}
+			return crane.Export(img, f)
 		},
 	}
 }

cmd/crane/cmd/list.go

@@ -16,7 +16,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -28,16 +27,17 @@ func NewCmdList(options *[]crane.Option) *cobra.Command {
 		Use:   "ls REPO",
 		Short: "List the tags in a repo",
 		Args:  cobra.ExactArgs(1),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			repo := args[0]
 			tags, err := crane.ListTags(repo, *options...)
 			if err != nil {
-				log.Fatalf("reading tags for %s: %v", repo, err)
+				return fmt.Errorf("reading tags for %s: %v", repo, err)
 			}
 
 			for _, tag := range tags {
 				fmt.Println(tag)
 			}
+			return nil
 		},
 	}
 }

cmd/crane/cmd/manifest.go

@@ -16,7 +16,6 @@ package cmd
 
 import (
 	"fmt"
-	"log"
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
@@ -28,13 +27,14 @@ func NewCmdManifest(options *[]crane.Option) *cobra.Command {
 		Use:   "manifest IMAGE",
 		Short: "Get the manifest of an image",
 		Args:  cobra.ExactArgs(1),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			src := args[0]
 			manifest, err := crane.Manifest(src, *options...)
 			if err != nil {
-				log.Fatalf("fetching manifest %s: %v", src, err)
+				return fmt.Errorf("fetching manifest %s: %v", src, err)
 			}
 			fmt.Print(string(manifest))
+			return nil
 		},
 	}
 }

cmd/crane/cmd/optimize.go

@@ -15,8 +15,6 @@
 package cmd
 
 import (
-	"log"
-
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/spf13/cobra"
 )
@@ -31,11 +29,9 @@ func NewCmdOptimize(options *[]crane.Option) *cobra.Command {
 		Aliases: []string{"opt"},
 		Short:   "Optimize a remote container image from src to dst",
 		Args:    cobra.ExactArgs(2),
-		Run: func(_ *cobra.Command, args []string) {
+		RunE: func(_ *cobra.Command, args []string) error {
 			src, dst := args[0], args[1]
-			if err := crane.Optimize(src, dst, files, *options...); err != nil {
-				log.Fatal(err)
-			}
+			return crane.Optimize(src, dst, files, *options...)
 		},
 	}