csana/docker-debug repository overview

⁠Docker container for debugging

This is a simple container for debugging purposes. You can use it as a companion container to an existing one. You can find the image on Dockerhub (https://hub.docker.com/r/csana/docker-debug/⁠)

The idea based on Janoszen's container (github.com/janoszen/docker-debug/) what he used on his devopsakademia.hu course (https://devopsakademia.hu/termek/hibakereses-docker-kornyezetben/⁠), I just added few more apps I often use.

⁠Usage

First, you need to indentify the already running container you want to debug (eg. docker ps). If your container is not running, this will not work.

Next, you have to launch this container while joining the existing containers namespaces. This will enable you to see its processes and network interface:

export TARGET="target container ID here"
docker run \
  --pid container:$TARGET \
  --net container:$TARGET \
  --cap-add NET_RAW \
  --cap-add NET_ADMIN \
  --cap-add SYS_PTRACE \
  --rm \
  -ti
  csana/docker-debug

or I usually using it as a bash function:

docker-debug() { docker run \
  --pid container:$1 \
  --net container:$1 \
  --cap-add NET_RAW \
  --cap-add NET_ADMIN \
  --cap-add SYS_PTRACE \
  --rm \
  -ti \
  csana/docker-debug; } 

then simply use:

docker-debug containerID

You are now in a container that has more privileges than your normal running container (you can strace, etc) but sees the same processes and network interface as the container you wish to debug.