feat: enhance ensureContainer method to check for existing containers and manage host port allocation

Author: mirkobrombin

plugins/docker_standard.go

@@ -159,6 +159,10 @@ func (d *DockerStandardPlugin) OnExit() error {
 	return nil
 }
 
+// ensureContainer first checks if a container already exists.
+// If it does, it reads the assigned host port from the container's labels (goup_port)
+// and stores it in state.hostPort. Otherwise, it builds/pulls the image,
+// allocates a free port, and starts the container (adding a label to record the port).
 func (d *DockerStandardPlugin) ensureContainer(domain string) error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
@@ -170,26 +174,38 @@ func (d *DockerStandardPlugin) ensureContainer(domain string) error {
 		return nil
 	}
 
-	// Generate unique container name using domain and container port.
-	containerName := fmt.Sprintf("goup_%s_%s", domain, state.config.ContainerPort)
-
-	d.DomainLogger.Infof("[DockerStandardPlugin] Starting container for domain=%s with tag %s", domain, containerName)
 	cliCmd := state.config.CLICommand
 	if cliCmd == "" {
 		cliCmd = "docker"
 		if _, err := exec.LookPath("docker"); err != nil {
 			cliCmd = "podman"
 		}
 	}
-	var workDir string
-	if state.config.DockerfilePath != "" {
-		workDir = filepath.Dir(state.config.DockerfilePath)
-	} else {
-		workDir = "."
+
+	// Generate unique container name using domain and container port.
+	containerName := fmt.Sprintf("goup_%s_%s", domain, state.config.ContainerPort)
+	d.DomainLogger.Infof("[DockerStandardPlugin] Checking for existing container with name=%s", containerName)
+
+	// Check if a container with the expected name already exists.
+	existingContainerID, err := RunDockerCLI(cliCmd, state.config.DockerfilePath, "ps", "-a",
+		"--filter", fmt.Sprintf("name=%s", containerName),
+		"--format", "{{.ID}}")
+	if err == nil && strings.TrimSpace(existingContainerID) != "" {
+		// Container exists; read its assigned port from the container labels.
+		assignedPort, err := RunDockerCLI(cliCmd, state.config.DockerfilePath, "inspect",
+			"--format", "{{ index .Config.Labels \"goup_port\"}}", containerName)
+		if err != nil || strings.TrimSpace(assignedPort) == "" {
+			return fmt.Errorf("container exists but goup_port label is missing or empty")
+		}
+		state.containerID = strings.TrimSpace(existingContainerID)
+		state.hostPort = strings.TrimSpace(assignedPort)
+		d.DomainLogger.Infof("[DockerStandardPlugin] Found existing container for domain=%s with ID=%s and hostPort=%s", domain, state.containerID, state.hostPort)
+		return nil
 	}
 
 	// Build image if Dockerfile is provided; otherwise, pull the image.
 	if state.config.DockerfilePath != "" {
+		workDir := filepath.Dir(state.config.DockerfilePath)
 		buildArgs := []string{"build", "-f", state.config.DockerfilePath, "-t", state.config.ImageName, workDir}
 		for key, val := range state.config.BuildArgs {
 			buildArgs = append(buildArgs, "--build-arg", fmt.Sprintf("%s=%s", key, val))
@@ -208,14 +224,21 @@ func (d *DockerStandardPlugin) ensureContainer(domain string) error {
 		}
 		d.PluginLogger.Infof("Pull output: %s", pullOutput)
 	}
+
 	// Allocate a free host port from a high range.
 	hostPort, err := tools.GetFreePort()
 	if err != nil {
 		return fmt.Errorf("failed to get free port: %v", err)
 	}
 
-	// Run container with host port mapping using the free port.
-	runArgs := []string{"run", "-d", "--name", containerName, "-p", fmt.Sprintf("%s:%s", hostPort, state.config.ContainerPort)}
+	// Run container with host port mapping using the free port,
+	// and add a label to record the assigned port.
+	runArgs := []string{
+		"run", "-d",
+		"--name", containerName,
+		"-p", fmt.Sprintf("%s:%s", hostPort, state.config.ContainerPort),
+		"--label", fmt.Sprintf("goup_port=%s", hostPort),
+	}
 	runArgs = append(runArgs, state.config.RunArgs...)
 	runArgs = append(runArgs, state.config.ImageName)
 	d.PluginLogger.Infof("[DockerStandardPlugin] Running container with command: %s %s", cliCmd, strings.Join(runArgs, " "))