func MergeImageConfig()

in image.go [80:146]
55 lines of code
17 McCabe index (conditional complexity)

func MergeImageConfig(dst *DockerImageConfig, src *ImageConfig) error {
	if src == nil {
		return nil
	}

	if src.Entrypoint != "" {
		split, err := shlex.Split(src.Entrypoint)
		if err != nil {
			return errors.Wrap(err, "error splitting entrypoint into args")
		}
		dst.Entrypoint = split
		// Reset cmd as this may be totally invalid now
		// This is the same behavior as the Dockerfile frontend
		dst.Cmd = nil
	}
	if src.Cmd != "" {
		split, err := shlex.Split(src.Cmd)
		if err != nil {
			return errors.Wrap(err, "error splitting cmd into args")
		}
		dst.Cmd = split
	}

	if len(src.Env) > 0 {
		// Env is append only
		// If the env var already exists, replace it
		envIdx := make(map[string]int)
		for i, env := range dst.Env {
			envIdx[env] = i
		}

		for _, env := range src.Env {
			if idx, ok := envIdx[env]; ok {
				dst.Env[idx] = env
			} else {
				dst.Env = append(dst.Env, env)
			}
		}
	}

	if src.WorkingDir != "" {
		dst.WorkingDir = src.WorkingDir
	}
	if src.StopSignal != "" {
		dst.StopSignal = src.StopSignal
	}

	if src.User != "" {
		dst.User = src.User
	}

	for k, v := range src.Volumes {
		if dst.Volumes == nil {
			dst.Volumes = make(map[string]struct{}, len(src.Volumes))
		}
		dst.Volumes[k] = v
	}

	for k, v := range src.Labels {
		if dst.Labels == nil {
			dst.Labels = make(map[string]string, len(src.Labels))
		}
		dst.Labels[k] = v
	}

	return nil
}