Copy Docker config into controller container (#89)

* Mount Docker config into controller container

* Check if docker config exists and its a regular file

* Copy docker config file

* poll on inspectResp.Running to wait for the command to exit

Author: ilopezluna

pkg/standalone/containers.go

@@ -1,6 +1,8 @@
 package standalone
 
 import (
+	"archive/tar"
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -27,6 +29,100 @@ const controllerContainerName = "docker-model-runner"
 // the conflicting container in a capture group.
 var concurrentInstallMatcher = regexp.MustCompile(`is already in use by container "([a-z0-9]+)"`)
 
+// copyDockerConfigToContainer copies the Docker config file from the host to the container
+// and sets up proper ownership and permissions for the modelrunner user.
+func copyDockerConfigToContainer(ctx context.Context, dockerClient *client.Client, containerID string) error {
+	dockerConfigPath := os.ExpandEnv("$HOME/.docker/config.json")
+	if s, err := os.Stat(dockerConfigPath); err != nil || s.Mode()&os.ModeType != 0 {
+		return nil
+	}
+
+	configData, err := os.ReadFile(dockerConfigPath)
+	if err != nil {
+		return fmt.Errorf("failed to read Docker config file: %w", err)
+	}
+
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	header := &tar.Header{
+		Name: ".docker/config.json",
+		Mode: 0600,
+		Size: int64(len(configData)),
+	}
+	if err := tw.WriteHeader(header); err != nil {
+		return fmt.Errorf("failed to write tar header: %w", err)
+	}
+	if _, err := tw.Write(configData); err != nil {
+		return fmt.Errorf("failed to write config data to tar: %w", err)
+	}
+	if err := tw.Close(); err != nil {
+		return fmt.Errorf("failed to close tar writer: %w", err)
+	}
+
+	// Ensure the .docker directory exists
+	mkdirCmd := "mkdir -p /home/modelrunner/.docker && chown modelrunner:modelrunner /home/modelrunner/.docker"
+	if err := execInContainer(ctx, dockerClient, containerID, mkdirCmd); err != nil {
+		return err
+	}
+
+	// Copy directly into the .docker directory
+	err = dockerClient.CopyToContainer(ctx, containerID, "/home/modelrunner", &buf, container.CopyToContainerOptions{
+		CopyUIDGID: true,
+	})
+	if err != nil {
+		return fmt.Errorf("failed to copy config file to container: %w", err)
+	}
+
+	// Set correct ownership and permissions
+	chmodCmd := "chown modelrunner:modelrunner /home/modelrunner/.docker/config.json && chmod 600 /home/modelrunner/.docker/config.json"
+	if err := execInContainer(ctx, dockerClient, containerID, chmodCmd); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func execInContainer(ctx context.Context, dockerClient *client.Client, containerID, cmd string) error {
+	execConfig := container.ExecOptions{
+		Cmd: []string{"sh", "-c", cmd},
+	}
+	execResp, err := dockerClient.ContainerExecCreate(ctx, containerID, execConfig)
+	if err != nil {
+		return fmt.Errorf("failed to create exec for command '%s': %w", cmd, err)
+	}
+	if err := dockerClient.ContainerExecStart(ctx, execResp.ID, container.ExecStartOptions{}); err != nil {
+		return fmt.Errorf("failed to start exec for command '%s': %w", cmd, err)
+	}
+
+	// Create a timeout context for the polling loop
+	timeoutCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	// Poll until the command finishes or timeout occurs
+	for {
+		inspectResp, err := dockerClient.ContainerExecInspect(ctx, execResp.ID)
+		if err != nil {
+			return fmt.Errorf("failed to inspect exec for command '%s': %w", cmd, err)
+		}
+
+		if !inspectResp.Running {
+			// Command has finished, now we can safely check the exit code
+			if inspectResp.ExitCode != 0 {
+				return fmt.Errorf("command '%s' failed with exit code %d", cmd, inspectResp.ExitCode)
+			}
+			return nil
+		}
+
+		// Brief sleep to avoid busy polling, with timeout check
+		select {
+		case <-time.After(100 * time.Millisecond):
+			// Continue polling
+		case <-timeoutCtx.Done():
+			return fmt.Errorf("command '%s' timed out after 10 seconds", cmd)
+		}
+	}
+}
+
 // FindControllerContainer searches for a running controller container. It
 // returns the ID of the container (if found), the container name (if any), the
 // full container summary (if found), or any error that occurred.
@@ -196,6 +292,12 @@ func CreateControllerContainer(ctx context.Context, dockerClient *client.Client,
 		_ = dockerClient.ContainerRemove(ctx, resp.ID, container.RemoveOptions{Force: true})
 		return fmt.Errorf("failed to start container %s: %w", controllerContainerName, err)
 	}
+
+	// Copy Docker config file if it exists
+	if err := copyDockerConfigToContainer(ctx, dockerClient, resp.ID); err != nil {
+		// Log warning but continue - don't fail container creation
+		printer.Printf("Warning: failed to copy Docker config: %v\n", err)
+	}
 	return nil
 }