feat: enabling running cdebug with images built locally (#11)

cmd/exec/exec_docker.go

@@ -16,6 +16,39 @@ import (
 	"github.com/iximiuz/cdebug/pkg/uuid"
 )
 
+// debugImageExistsLocally checks if the debug image exists in the host and that it matches the target container
+// platform.
+func debugImageExistsLocally(ctx context.Context, client *docker.Client, debugImage string, debugImagePlatform string, target types.ContainerJSON) (bool, error) {
+	debugImageInspect, _, err := client.ImageInspectWithRaw(ctx, debugImage)
+	if err != nil {
+		// err means that the requested image wasn't found,
+		// therefore it needs to be pulled
+		logrus.Debugf("The image %s wasn't found locally", debugImage)
+		return false, nil
+	}
+
+	debugImageOs := debugImageInspect.Os
+	debugImageArchitecture := debugImageInspect.Architecture
+	// override through --platform flag
+	if debugImagePlatform != "" {
+		fmt.Sscanf(debugImagePlatform, "%s/%s", &debugImageOs, &debugImageArchitecture)
+	}
+
+	// target.Platform only contains the Os but doesn't have the Arch, however we can
+	// get the Os & Arch by analyzing the image using target.Image
+	targetImageInspect, _, err := client.ImageInspectWithRaw(ctx, target.Image)
+	if err != nil {
+		return false, fmt.Errorf("failed to inspect image %s: %v", target.Image, err)
+	}
+
+	// debug image exists, also check that the platform matches the target image platform
+	if debugImageArchitecture != targetImageInspect.Architecture || debugImageOs != targetImageInspect.Os {
+		return false, nil
+	}
+
+	return true, nil
+}
+
 func runDebuggerDocker(ctx context.Context, cli cliutil.CLI, opts *options) error {
 	client, err := docker.NewClient(docker.Options{
 		Out:  cli.AuxStream(),
@@ -33,16 +66,23 @@ func runDebuggerDocker(ctx context.Context, cli cliutil.CLI, opts *options) erro
 		return errTargetNotRunning
 	}
 
-	cli.PrintAux("Pulling debugger image...\n")
-	if err := client.ImagePullEx(ctx, opts.image, types.ImagePullOptions{
-		Platform: func() string {
-			if len(opts.platform) == 0 {
-				return target.Platform
-			}
-			return opts.platform
-		}(),
-	}); err != nil {
-		return errCannotPull(opts.image, err)
+	imageExists, err := debugImageExistsLocally(ctx, client, opts.image, opts.platform, target)
+	if err != nil {
+		return err
+	}
+
+	if !imageExists {
+		cli.PrintAux("Pulling debugger image...\n")
+		if err := client.ImagePullEx(ctx, opts.image, types.ImagePullOptions{
+			Platform: func() string {
+				if len(opts.platform) == 0 {
+					return target.Platform
+				}
+				return opts.platform
+			}(),
+		}); err != nil {
+			return errCannotPull(opts.image, err)
+		}
 	}
 
 	runID := uuid.ShortID()

e2e/exec/docker_test.go

@@ -1,6 +1,8 @@
 package exec
 
 import (
+	"fmt"
+	"regexp"
 	"testing"
 
 	"gotest.tools/assert"
@@ -21,6 +23,27 @@ func TestExecDockerSimple(t *testing.T) {
 	assert.Check(t, cmp.Contains(res.Stdout(), "debian"))
 }
 
+func TestExecDockerUseLocalImage(t *testing.T) {
+	localImage, cleanupLocalImage := fixture.DockerBuildLocalImage(t)
+	defer cleanupLocalImage()
+
+	targetImageID, targetImageCleanup := fixture.DockerRunBackground(t, fixture.ImageNginx, nil)
+	defer targetImageCleanup()
+
+	res := icmd.RunCmd(
+		icmd.Command("cdebug", "--image", localImage, "-l=debug", "exec", "--rm", "-q", targetImageID, "cat", "/etc/os-release"),
+	)
+	res.Assert(t, icmd.Success)
+	assert.Check(t, cmp.Contains(res.Stdout(), "debian"))
+	assert.Assert(t, func() cmp.Result {
+		re := regexp.MustCompile("Pulling debugger image...")
+		if re.MatchString(res.Stdout()) {
+			return cmp.ResultFailure(fmt.Sprintf("Image %s shouldn't be pulled because it only exists locally", localImage))
+		}
+		return cmp.ResultSuccess
+	})
+}
+
 func TestExecDockerHostNamespaces(t *testing.T) {
 	targetID, cleanup := fixture.DockerRunBackground(t, fixture.ImageNginx,
 		[]string{"--net", "host", "--pid", "host"},

e2e/internal/fixture/Dockerfile

@@ -0,0 +1 @@
+FROM busybox:musl

e2e/internal/fixture/fixture.go

@@ -2,6 +2,8 @@ package fixture
 
 import (
 	"os/exec"
+	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -89,6 +91,30 @@ func DockerRunBackground(
 	return contID, cleanup
 }
 
+func DockerBuildLocalImage(
+	t *testing.T,
+) (string, func()) {
+	localImage := "thisimageonlyexistslocally:1.0"
+
+	// Get dirname of current file, assumes that the Dockerfile lives next to this file.
+	_, filename, _, ok := runtime.Caller(0)
+	if !ok {
+		t.Fatalf("Failed to get filename")
+	}
+	dirname := filepath.Dir(filename)
+
+	cmd := dockerCmd("build", "-t", localImage, dirname)
+
+	res := icmd.RunCmd(cmd)
+	res.Assert(t, icmd.Success)
+
+	cleanup := func() {
+		icmd.RunCmd(dockerCmd("rmi", localImage)).Assert(t, icmd.Success)
+	}
+
+	return localImage, cleanup
+}
+
 func NerdctlRunBackground(
 	t *testing.T,
 	image string,