docker run -it --net container:<container_name> nicolaka/netshoot

Description

Purpose: Docker and Kubernetes network troubleshooting can become complex. With proper understanding of how Docker and Kubernetes networking works and the right set of tools, you can troubleshoot and resolve these networking issues. The netshoot container has a set of powerful networking tshooting tools that can be used to troubleshoot Docker networking issues. Along with these tools come a set of use-cases that show how this container can be used in real-world scenarios.

Network Namespaces: Before starting to use this tool, it's important to go over one key topic: Network Namespaces. Network namespaces provide isolation of the system resources associated with networking. Docker uses network and other type of namespaces (pid,mount,user..etc) to create an isolated environment for each container. Everything from interfaces, routes, and IPs is completely isolated within the network namespace of the container.

Kubernetes also uses network namespaces. Kubelets creates a network namespace per pod where all containers in that pod share that same network namespace (eths,IP, tcp sockets...etc). This is a key difference between Docker containers and Kubernetes pods.

Cool thing about namespaces is that you can switch between them. You can enter a different container's network namespace, perform some troubleshooting on its network's stack with tools that aren't even installed on that container. Additionally, netshoot can be used to troubleshoot the host itself by using the host's network namespace. This allows you to perform any troubleshooting without installing any new packages directly on the host or your application's package.

Cheatsheat

• Container networking analysis: docker run -it --net container:<container_name> nicolaka/netshoot
• Host network inspect: docker run -it --net host nicolaka/netshoot

Kubernetes

If you want to spin up a throw away container for debugging.

$ kubectl run tmp-shell --rm -i --tty --image nicolaka/netshoot -- /bin/bash

And if you want to spin up a container on the host's network namespace.

$ kubectl run tmp-shell --rm -i --tty --overrides='{"spec": {"hostNetwork": true}}' --image nicolaka/netshoot -- /bin/bash