Add inspect command (#95)

* Add inspect commadn

* Update README

Author: ferranbt

README.md

@@ -68,6 +68,23 @@ $ builder-playground cook l1 --latest-fork --output ~/my-builder-testnet --genes
 
 To stop the playground, press `Ctrl+C`.
 
+## Inspect
+
+Builder-playground supports inspecting the connection of a service to a specific port.
+
+```bash
+$ builder-playground inspect <service> <port>
+```
+
+Example:
+
+```bash
+$ builder-playground cook opstack
+$ builder-playground inspect op-geth authrpc
+```
+
+This command starts a `tcpflow` container in the same network interface as the service and captures the traffic to the specified port.
+
 ## Internals
 
 ### Execution Flow

internal/inspect.go

@@ -0,0 +1,127 @@
+package internal
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/docker/docker/api/types/container"
+	"github.com/docker/docker/api/types/filters"
+	"github.com/docker/docker/client"
+)
+
+// Inspect incldues the logic for the inspect command
+func Inspect(ctx context.Context, serviceName, portName string) error {
+	client, err := newDockerClient()
+	if err != nil {
+		return fmt.Errorf("failed to create docker client: %w", err)
+	}
+
+	serviceID, portNum, err := retrieveContainerDetails(client, serviceName, portName)
+	if err != nil {
+		return fmt.Errorf("failed to retrieve container details: %w", err)
+	}
+
+	return runTcpFlow(ctx, client, serviceID, portNum)
+}
+
+func retrieveContainerDetails(client *client.Client, serviceName, portName string) (string, string, error) {
+	// Get the service by name
+	containers, err := client.ContainerList(context.Background(), container.ListOptions{
+		Filters: filters.NewArgs(filters.Arg("label", "service="+serviceName)),
+		All:     true,
+	})
+	if err != nil {
+		return "", "", fmt.Errorf("error getting container list: %w", err)
+	}
+
+	size := len(containers)
+	if size == 0 {
+		return "", "", fmt.Errorf("no containers found for service %s", serviceName)
+	} else if size > 1 {
+		return "", "", fmt.Errorf("multiple containers found for service %s", serviceName)
+	}
+
+	container := containers[0]
+
+	// Get the container details to find the port mapping in the labels as port.<name>
+	containerDetails, err := client.ContainerInspect(context.Background(), container.ID)
+	if err != nil {
+		return "", "", fmt.Errorf("error inspecting container %s: %w", container.ID, err)
+	}
+
+	// Check if the port name is in the labels
+	portLabel := fmt.Sprintf("port.%s", portName)
+	portNum, ok := containerDetails.Config.Labels[portLabel]
+	if !ok {
+		return "", "", fmt.Errorf("port %s not found in container %s", portName, container.ID)
+	}
+
+	return container.ID, portNum, nil
+}
+
+func runTcpFlow(ctx context.Context, client *client.Client, containerID, portName string) error {
+	// Create container config for tcpflow
+	config := &container.Config{
+		Image:        "appropriate/tcpflow:latest",
+		Cmd:          []string{"-c", "-p", "-i", "eth0", "port", portName},
+		Tty:          true,
+		AttachStdout: true,
+		AttachStderr: true,
+	}
+
+	// Host config with network mode and capabilities
+	hostConfig := &container.HostConfig{
+		NetworkMode: container.NetworkMode("container:" + containerID),
+		CapAdd:      []string{"NET_ADMIN"},
+	}
+
+	// Create the container
+	resp, err := client.ContainerCreate(ctx, config, hostConfig, nil, nil, "")
+	if err != nil {
+		return fmt.Errorf("failed to create container: %w", err)
+	}
+
+	// Start the container
+	if err := client.ContainerStart(ctx, resp.ID, container.StartOptions{}); err != nil {
+		return fmt.Errorf("failed to start container: %w", err)
+	}
+
+	// Get container logs and stream them
+	logOptions := container.LogsOptions{
+		ShowStdout: true,
+		ShowStderr: true,
+		Follow:     true,
+		Timestamps: false,
+	}
+
+	logs, err := client.ContainerLogs(ctx, resp.ID, logOptions)
+	if err != nil {
+		return fmt.Errorf("failed to get container logs: %w", err)
+	}
+	defer logs.Close()
+
+	// Start copying logs to stdout
+	go func() {
+		_, err := io.Copy(os.Stdout, logs)
+		if err != nil && err != io.EOF {
+			fmt.Fprintf(os.Stderr, "Error copying logs: %v\n", err)
+		}
+	}()
+
+	// Wait for interrupt signal
+	<-ctx.Done()
+
+	// Cleanup: stop and remove the container
+	timeout := 5
+	if err := client.ContainerStop(context.Background(), resp.ID, container.StopOptions{Timeout: &timeout}); err != nil {
+		fmt.Fprintf(os.Stderr, "Error stopping container: %v\n", err)
+	}
+
+	if err := client.ContainerRemove(context.Background(), resp.ID, container.RemoveOptions{Force: true}); err != nil {
+		fmt.Fprintf(os.Stderr, "Error removing container: %v\n", err)
+	}
+
+	return nil
+}

internal/local_runner.go

@@ -80,11 +80,19 @@ type taskUI struct {
 	style    lipgloss.Style
 }
 
-func NewLocalRunner(out *output, manifest *Manifest, overrides map[string]string, interactive bool) (*LocalRunner, error) {
+func newDockerClient() (*client.Client, error) {
 	client, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
 	if err != nil {
 		return nil, fmt.Errorf("failed to create docker client: %w", err)
 	}
+	return client, nil
+}
+
+func NewLocalRunner(out *output, manifest *Manifest, overrides map[string]string, interactive bool) (*LocalRunner, error) {
+	client, err := newDockerClient()
+	if err != nil {
+		return nil, fmt.Errorf("failed to create docker client: %w", err)
+	}
 
 	// merge the overrides with the manifest overrides
 	if overrides == nil {
@@ -494,6 +502,21 @@ func (d *LocalRunner) toDockerComposeService(s *service) (map[string]interface{}
 		return nil, fmt.Errorf("failed to validate image %s: %w", imageName, err)
 	}
 
+	labels := map[string]string{
+		// It is important to use the playground label to identify the containers
+		// during the cleanup process
+		"playground": "true",
+		"service":    s.Name,
+	}
+
+	// add the local ports exposed by the service as labels
+	// we have to do this for now since we do not store the manifest in JSON yet.
+	// Otherwise, we could use that directly
+	for _, port := range s.ports {
+		labels[fmt.Sprintf("port.%s", port.Name)] = fmt.Sprintf("%d", port.Port)
+	}
+
+	// add the ports to the labels as well
 	service := map[string]interface{}{
 		"image":   imageName,
 		"command": args,
@@ -503,9 +526,7 @@ func (d *LocalRunner) toDockerComposeService(s *service) (map[string]interface{}
 		},
 		// Add the ethereum network
 		"networks": []string{networkName},
-		// It is important to use the playground label to identify the containers
-		// during the cleanup process
-		"labels": map[string]string{"playground": "true"},
+		"labels":   labels,
 	}
 
 	if len(envs) > 0 {

main.go

@@ -113,6 +113,33 @@ var artifactsAllCmd = &cobra.Command{
 	},
 }
 
+var inspectCmd = &cobra.Command{
+	Use:   "inspect",
+	Short: "Inspect a connection between two services",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		// two arguments, the name of the service and the name of the connection
+		if len(args) != 2 {
+			return fmt.Errorf("please specify a service name and a connection name")
+		}
+		serviceName := args[0]
+		connectionName := args[1]
+
+		sig := make(chan os.Signal, 1)
+		signal.Notify(sig, os.Interrupt)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		go func() {
+			<-sig
+			cancel()
+		}()
+
+		if err := internal.Inspect(ctx, serviceName, connectionName); err != nil {
+			return fmt.Errorf("failed to inspect connection: %w", err)
+		}
+		return nil
+	},
+}
+
 var recipes = []internal.Recipe{
 	&internal.L1Recipe{},
 	&internal.OpRecipe{},
@@ -151,6 +178,7 @@ func main() {
 	rootCmd.AddCommand(cookCmd)
 	rootCmd.AddCommand(artifactsCmd)
 	rootCmd.AddCommand(artifactsAllCmd)
+	rootCmd.AddCommand(inspectCmd)
 
 	if err := rootCmd.Execute(); err != nil {
 		fmt.Println(err)