use cobra flags

README.md

@@ -21,34 +21,31 @@ Alternatively, you can also build from source by cloning the repo and running `g
 `incert` supports the following flags:
 
 ```shell
-  -ca-certs-file string
-        The path to the local CA certificates file
-  -ca-certs-image-url string
-        The URL of an image to extract the CA certificates from
-  -dest-image-url string
-        The URL of the image to push the modified image to
-  -image-cert-path string
-        The path to the certificate file in the image (optional) (default "/etc/ssl/certs/ca-certificates.crt")
-  -image-url string
-        The URL of the image to append the CA certificates to
-  -output-certs-path string
-        Output the (appended) certificates file from the image to a local file (optional)
-  -owner-group-id int
-        The group ID of the owner of the certificate file in the image (optional)
-  -owner-user-id int
-        The user ID of the owner of the certificate file in the image (optional)
-  -platform string
-        The platform to build the image for (default "linux/amd64")
-  -replace-certs
-        Replace the certificates in the certificate file instead of appending them
+Appends CA certificates to Docker images and pushes the modified image to a specified registry.
+
+Usage:
+  incert [flags]
+
+Flags:
+      --ca-certs-file string        The path to the local CA certificates file
+      --ca-certs-image-url string   The URL of an image to extract the CA certificates from
+      --dest-image-url string       The URL of the image to push the modified image to
+  -h, --help                        help for incert
+      --image-cert-path string      The path to the certificate file in the image (optional) (default "/etc/ssl/certs/ca-certificates.crt")
+      --image-url string            The URL of the image to append the CA certificates to
+      --output-certs-path string    Output the (appended) certificates file from the image to a local file (optional)
+      --owner-group-id int          The group ID of the owner of the certificate file in the image (optional)
+      --owner-user-id int           The user ID of the owner of the certificate file in the image (optional)
+      --platform string             The platform to build the image for (default "linux/amd64")
+      --replace-certs               Replace the certificates in the certificate file instead of appending them
 ```
 
 ## Example
 
 To append a corporate CA certificate to an image, use the following command:
 
 ```bash
-$ incert -image-url=mycompany/myimage:latest -ca-certs-file=/path/to/cacerts.pem -dest-image-url=myregistry/myimage:latest
+$ incert --image-url=mycompany/myimage:latest --ca-certs-file=/path/to/cacerts.pem --dest-image-url=myregistry/myimage:latest
 ```
 
 This will append the certificates in `/path/to/cacerts.pem` to the `mycompany/myimage:latest` image and push the modified image to `myregistry/myimage:latest`.

go.mod

@@ -4,19 +4,24 @@ go 1.23.0
 
 toolchain go1.23.5
 
-require github.com/google/go-containerregistry v0.20.3
+require (
+	github.com/google/go-containerregistry v0.20.3
+	github.com/spf13/cobra v1.8.1
+)
 
 require (
 	github.com/containerd/stargz-snapshotter/estargz v0.16.3 // indirect
 	github.com/docker/cli v27.5.0+incompatible // indirect
 	github.com/docker/distribution v2.8.3+incompatible // indirect
 	github.com/docker/docker-credential-helpers v0.8.2 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/klauspost/compress v1.17.11 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.1.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/sirupsen/logrus v1.9.3 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/vbatts/tar-split v0.11.6 // indirect
 	golang.org/x/sync v0.10.0 // indirect
 	golang.org/x/sys v0.29.0 // indirect

go.sum

@@ -1,5 +1,6 @@
 github.com/containerd/stargz-snapshotter/estargz v0.16.3 h1:7evrXtoh1mSbGj/pfRccTampEyKpjpOnS3CyiV1Ebr8=
 github.com/containerd/stargz-snapshotter/estargz v0.16.3/go.mod h1:uyr4BfYfOj3G9WBVE8cOlQmXAbPN9VEQpBBeJIuOipU=
+github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -13,6 +14,8 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-containerregistry v0.20.3 h1:oNx7IdTI936V8CQRveCjaxOiegWwvM7kqkbXTpyiovI=
 github.com/google/go-containerregistry v0.20.3/go.mod h1:w00pIgBRDVUDFM6bq+Qx8lwNWK+cxgCuX1vd3PIBDNI=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/klauspost/compress v1.17.11 h1:In6xLpyWOi1+C7tXUUWv2ot1QvBjxevKAaI6IXrJmUc=
 github.com/klauspost/compress v1.17.11/go.mod h1:pMDklpSncoRMuLFrf1W9Ss9KT+0rH90U12bZKk7uwG0=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
@@ -25,8 +28,13 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
 github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
+github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=

main.go

@@ -9,13 +9,15 @@ import (
 	"archive/tar"
 	"bytes"
 	"encoding/pem"
-	"flag"
+	"errors"
 	"fmt"
 	"io"
 	"log"
 	"os"
 	"strings"
 
+	"github.com/spf13/cobra"
+
 	"github.com/google/go-containerregistry/pkg/authn"
 	"github.com/google/go-containerregistry/pkg/name"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
@@ -38,99 +40,113 @@ var (
 )
 
 func init() {
-	flag.StringVar(&imageURL, "image-url", "", "The URL of the image to append the CA certificates to")
-	flag.StringVar(&caCertFile, "ca-certs-file", "", "The path to the local CA certificates file")
-	flag.StringVar(&caCertsImageURL, "ca-certs-image-url", "", "The URL of an image to extract the CA certificates from")
-	flag.StringVar(&destImageURL, "dest-image-url", "", "The URL of the image to push the modified image to")
-	flag.StringVar(&platformStr, "platform", "linux/amd64", "The platform to build the image for")
-
-	flag.StringVar(&imageCertPath, "image-cert-path", "/etc/ssl/certs/ca-certificates.crt", "The path to the certificate file in the image (optional)")
-	flag.IntVar(&ownerUserID, "owner-user-id", 0, "The user ID of the owner of the certificate file in the image (optional)")
-	flag.IntVar(&ownerGroupID, "owner-group-id", 0, "The group ID of the owner of the certificate file in the image (optional)")
-	flag.StringVar(&outputCerts, "output-certs-path", "", "Output the (appended) certificates file from the image to a local file (optional)")
-	flag.BoolVar(&replaceCerts, "replace-certs", false, "Replace the certificates in the certificate file instead of appending them")
+	rootCmd.Flags().StringVar(&imageURL, "image-url", "", "The URL of the image to append the CA certificates to")
+	rootCmd.Flags().StringVar(&caCertFile, "ca-certs-file", "", "The path to the local CA certificates file")
+	rootCmd.Flags().StringVar(&caCertsImageURL, "ca-certs-image-url", "", "The URL of an image to extract the CA certificates from")
+	rootCmd.Flags().StringVar(&destImageURL, "dest-image-url", "", "The URL of the image to push the modified image to")
+	rootCmd.Flags().StringVar(&platformStr, "platform", "linux/amd64", "The platform to build the image for")
+
+	rootCmd.Flags().StringVar(&imageCertPath, "image-cert-path", "/etc/ssl/certs/ca-certificates.crt", "The path to the certificate file in the image (optional)")
+	rootCmd.Flags().IntVar(&ownerUserID, "owner-user-id", 0, "The user ID of the owner of the certificate file in the image (optional)")
+	rootCmd.Flags().IntVar(&ownerGroupID, "owner-group-id", 0, "The group ID of the owner of the certificate file in the image (optional)")
+	rootCmd.Flags().StringVar(&outputCerts, "output-certs-path", "", "Output the (appended) certificates file from the image to a local file (optional)")
+	rootCmd.Flags().BoolVar(&replaceCerts, "replace-certs", false, "Replace the certificates in the certificate file instead of appending them")
+
+	_ = rootCmd.MarkFlagRequired("image-url")
+	_ = rootCmd.MarkFlagRequired("dest-image-url")
 }
 
-func usage() {
-	flag.Usage()
-	os.Exit(1)
+func main() {
+	if err := rootCmd.Execute(); err != nil {
+		os.Exit(1)
+	}
 }
 
-func main() {
+var rootCmd = &cobra.Command{
+	Use:          "incert",
+	Short:        "Appends CA certificates to Docker images and pushes the modified image to a specified registry.",
+	SilenceUsage: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		return do(cmd, args)
+	},
+}
 
+// Fetch the remote image
+func fetchImage(imageURL string, platform v1.Platform) (v1.Image, error) {
+	ref, err := name.ParseReference(imageURL)
+	if err != nil {
+		return nil, err
+	}
+	img, err := remote.Image(ref, remote.WithAuthFromKeychain(authn.DefaultKeychain), remote.WithPlatform((platform)))
+	if err != nil {
+		return nil, err
+	}
+	return img, nil
+}
+
+func do(_ *cobra.Command, _ []string) error {
 	var platform v1.Platform
-	flag.Parse()
 
-	if imageURL == "" || destImageURL == "" || (caCertFile == "" && caCertsImageURL == "") {
-		usage()
+	if caCertFile == "" && caCertsImageURL == "" {
+		return errors.New("either --ca-certs-file or --ca-certs-image-url must be provided")
 	}
 
 	if platformStr != "" {
 		p, err := v1.ParsePlatform(platformStr)
 		if err != nil {
-			log.Fatalf("Failed to parse platform: %s", err)
+			return fmt.Errorf("Failed to parse platform: %s", err)
 		}
 		platform = *p
 	}
 
 	// Get the cert bytes
 	caCertBytes, err := getCertBytes(platform)
 	if err != nil {
-		log.Fatalf("Failed to get certificate bytes: %s", err)
+		return fmt.Errorf("Failed to get certificate bytes: %s", err)
 	}
 
 	// Sanity check to make sure the caCertBytes are actually a list of pem-encoded certificates
 	block, _ := pem.Decode(caCertBytes)
 	if block == nil || block.Type != "CERTIFICATE" {
-		log.Fatalf("Failed to find any certificates in %s", caCertFile)
+		return fmt.Errorf("Failed to find any certificates in %s", caCertFile)
 	}
 
 	img, err := fetchImage(imageURL, platform)
 	if err != nil {
-		log.Fatalf("Failed to fetch image %s: %s\n", imageURL, err)
+		return fmt.Errorf("Failed to fetch image %s: %s\n", imageURL, err)
 	}
 
 	newImg, err := newImage(img, caCertBytes)
 	if err != nil {
-		log.Fatalf("Failed to create new image: %s\n", err)
+		return fmt.Errorf("Failed to create new image: %s\n", err)
 	}
 
 	if outputCerts != "" {
 		if err := os.WriteFile(outputCerts, caCertBytes, 0644); err != nil {
-			log.Fatalf("Failed to write certificates to file %s: %s.\n", outputCerts, err)
+			return fmt.Errorf("Failed to write certificates to file %s: %s.\n", outputCerts, err)
 		}
 	}
 
 	newRef, err := name.ParseReference(destImageURL)
 	if err != nil {
-		log.Fatalf("Failed to parse destination image URL %s: %s\n", destImageURL, err)
+		return fmt.Errorf("Failed to parse destination image URL %s: %s\n", destImageURL, err)
 	}
 
 	// Push the modified image back to the registry
 	err = remote.Write(newRef, newImg, remote.WithAuthFromKeychain(authn.DefaultKeychain))
 	if err != nil {
-		log.Fatalf("Failed to push modified image %s: %s\n", newRef.String(), err)
+		return fmt.Errorf("Failed to push modified image %s: %s\n", newRef.String(), err)
 	}
 
 	fmt.Fprintf(os.Stderr, "Successfully appended CA certificates to image %s\n", newRef.String())
 	h, err := newImg.Digest()
 	if err != nil {
-		log.Fatalf("Failed to get digest of image %s: %s\n", newRef.String(), err)
+		return fmt.Errorf("Failed to get digest of image %s: %s\n", newRef.String(), err)
 	}
+
 	fmt.Printf("%s@sha256:%s\n", newRef.String(), h.Hex)
-}
 
-// Fetch the remote image
-func fetchImage(imageURL string, platform v1.Platform) (v1.Image, error) {
-	ref, err := name.ParseReference(imageURL)
-	if err != nil {
-		return nil, err
-	}
-	img, err := remote.Image(ref, remote.WithAuthFromKeychain(authn.DefaultKeychain), remote.WithPlatform((platform)))
-	if err != nil {
-		return nil, err
-	}
-	return img, nil
+	return nil
 }
 
 func getCertBytes(platform v1.Platform) ([]byte, error) {
@@ -139,21 +155,22 @@ func getCertBytes(platform v1.Platform) ([]byte, error) {
 		// Read the contents of the local CA certificates file
 		caCertBytes, err := os.ReadFile(caCertFile)
 		if err != nil {
-			log.Fatalf("Failed to read CA certificates file %s: %s\n", caCertFile, err)
+			return []byte{}, fmt.Errorf("Failed to read CA certificates file %s: %s\n", caCertFile, err)
 		}
 
 		// Sanity check to make sure the caCertBytes are actually a list of pem-encoded certificates
 		block, _ := pem.Decode(caCertBytes)
 		if block == nil || block.Type != "CERTIFICATE" {
-			log.Fatalf("Failed to find any certificates in %s", caCertFile)
+			return []byte{}, fmt.Errorf("Failed to find any certificates in %s", caCertFile)
 		}
 		return caCertBytes, nil
 	} else {
 		// Fetch the remote image and its manifest
 		img, err := fetchImage(caCertsImageURL, platform)
 		if err != nil {
-			log.Fatalf("Failed to fetch image %s: %s\n", caCertsImageURL, err)
+			return []byte{}, fmt.Errorf("Failed to fetch image %s: %s\n", caCertsImageURL, err)
 		}
+
 		return extractCACerts(img)
 	}
 }
@@ -173,6 +190,7 @@ func extractCACerts(img v1.Image) ([]byte, error) {
 			return io.ReadAll(tr)
 		}
 	}
+
 	return nil, fmt.Errorf("failed to find %s in remote image", imageCertPath)
 }
 
@@ -191,7 +209,7 @@ func newImage(old v1.Image, caCertBytes []byte) (v1.Image, error) {
 	// Create a new tar file with the modified ca-certificates file
 	buf := bytes.Buffer{}
 	newTar := tar.NewWriter(&buf)
-	newTar.WriteHeader(&tar.Header{
+	_ = newTar.WriteHeader(&tar.Header{
 		Name: imageCertPath,
 		Mode: 0644,
 		Size: int64(len(newCaCertBytes)),