chore: internal docker package with handy PullImage and CreateContainerWithImagePull methods

internal/docker/image.go

@@ -0,0 +1,100 @@
+package docker
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+
+	dockercommand "github.com/docker/cli/cli/command"
+	dockerconfig "github.com/docker/cli/cli/config"
+	"github.com/docker/docker/api/types/image"
+	"github.com/docker/docker/api/types/registry"
+	"github.com/docker/docker/pkg/jsonmessage"
+)
+
+type PullImageMessage struct {
+	Message jsonmessage.JSONMessage
+	Err     error
+}
+
+// PullImage pulls a Docker image and returns a channel to receive progress messages.
+func (cli *Client) PullImage(
+	ctx context.Context, image string, opts image.PullOptions,
+) (<-chan PullImageMessage, error) {
+	if opts.RegistryAuth == "" {
+		// Try to retrieve the authentication token for the image from the default local Docker config file.
+		if encodedAuth, err := RetrieveLocalDockerRegistryAuth(image); err == nil {
+			opts.RegistryAuth = encodedAuth
+		}
+	}
+
+	respBody, err := cli.ImagePull(ctx, image, opts)
+	if err != nil {
+		return nil, err
+	}
+	defer respBody.Close()
+
+	decoder := json.NewDecoder(respBody)
+	ch := make(chan PullImageMessage)
+
+	go func() {
+		defer close(ch)
+		var jm jsonmessage.JSONMessage
+
+		for {
+			if err = decoder.Decode(&jm); err != nil {
+				if errors.Is(err, io.EOF) {
+					break
+				}
+				ch <- PullImageMessage{Err: fmt.Errorf("decode image pull message: %w", err)}
+				break
+			}
+
+			msg := PullImageMessage{Message: jm}
+			if jm.Error != nil {
+				msg.Err = errors.New(jm.Error.Message)
+			}
+
+			select {
+			case err = <-ctx.Done():
+				ch <- PullImageMessage{Err: ctx.Err()}
+				return
+			default:
+				ch <- msg
+			}
+		}
+	}()
+
+	return ch, nil
+}
+
+// RetrieveLocalDockerRegistryAuth retrieves the authentication token for the specified image from the local Docker
+// config file. It returns the encoded authentication token if it contains any credentials, or an empty string if
+// no credentials are found.
+func RetrieveLocalDockerRegistryAuth(image string) (string, error) {
+	// Try to retrieve the authentication token for the image from the default local Docker config file.
+	dockerConfig := dockerconfig.LoadDefaultConfigFile(os.Stderr)
+	encodedAuth, err := dockercommand.RetrieveAuthTokenFromImage(dockerConfig, image)
+	if err != nil {
+		return "", err
+	}
+	// The encodedAuth can be a base64-encoded "{}" (empty JSON object) or include a server address but no credentials.
+	// Return encodedAuth only if it contains any credentials.
+	auth, err := registry.DecodeAuthConfig(encodedAuth)
+	if err != nil {
+		return "", fmt.Errorf("decode auth config: %w", err)
+	}
+
+	if auth.Username == "" &&
+		auth.Password == "" &&
+		auth.Auth == "" &&
+		auth.IdentityToken == "" &&
+		auth.RegistryToken == "" {
+		return "", nil
+	}
+
+	return encodedAuth, nil
+}