Running Wireshark in Docker Containers

main.go

package main

// This is a cleaned up version of the code found in:
//
// https://medium.com/@chughtapan/running-wireshark-on-docker-ac90ebc4907b
//
// Added:
//     - Container ID passed as command-line argument
//     - Error handling

import (
	"fmt"
	"net"
	"os"
	"os/exec"
	"runtime"

	"github.com/vishvananda/netns"
)

func main() {
	if len(os.Args) == 1 {
		fmt.Fprintln(os.Stderr, "error: missing required arg: container-id")
		os.Exit(1)
	}

	// Lock the OS Thread so we don’t accidentally switch namespaces.
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	// Save the current network namespace.
	origns, err := netns.Get()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error getting current network namespace: %s\n", err)
		os.Exit(1)
	}
	defer origns.Close()

	// Get the network namespace based on container id.
	newns, err := netns.GetFromDocker(os.Args[1])
	if err != nil {
		fmt.Fprintf(os.Stderr, "error getting network namespace from docker: %s\n", err)
		os.Exit(1)
	}
	defer newns.Close()

	netns.Set(newns)

	// Do something with the network namespace.
	ifaces, err := net.Interfaces()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error getting network interfaces: %s\n", err)
		os.Exit(1)
	}
	fmt.Printf("interfaces: %v\n", ifaces)
	cmd := exec.Command("tshark", "-z", "conv,ip", "-i", "eth0")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Stdin = os.Stdin
	if err := cmd.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "error running cmd: %s\n", err)
		os.Exit(1)
	}

	// Return to original namespace.
	netns.Set(origns)
}