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Privileged mode: Running ctop in docker under SELinux

Felix Terkhorn
Independent software producer specialized in data and distributed systems. Past: tech lead for Disney+ DRM (NYC), consulting and contracting (NYC), startup scene, Salesforce, full-time lab staff.
・Updated on ・1 min read

Some programs like ctop are nice to run using docker containers, so that you don't have to manually download a binary and copy it into /usr/local/bin, where it will sit in a sad little corner, unmanaged by apt or yum.

GitHub logo bcicen / ctop

Top-like interface for container metrics

ctop

release homebrew

Top-like interface for container metrics

ctop provides a concise and condensed overview of real-time metrics for multiple containers:

ctop

as well as a single container view for inspecting a specific container.

ctop comes with built-in support for Docker and runC; connectors for other container and cluster systems are planned for future releases.

Install

Fetch the latest release for your platform:

Debian/Ubuntu

Maintained by a third party

echo "deb http://packages.azlux.fr/debian/ buster main" | sudo tee /etc/apt/sources.list.d/azlux.list
wget -qO - https://azlux.fr/repo.gpg.key | sudo apt-key add -
sudo apt update
sudo apt install docker-ctop
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Arch

ctop is available for Arch in the AUR

Linux (Generic)

sudo wget https://github.com/bcicen/ctop/releases/download/v0.7.5/ctop-0.7.5-linux-amd64 -O /usr/local/bin/ctop
sudo chmod +x /usr/local/bin/ctop
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OS X

brew install ctop
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or

sudo curl -Lo /usr/local/bin/ctop https://github.com/bcicen/ctop/releases/download/v0.7.5/ctop-0.7.5-darwin-amd64
sudo chmod +x /usr/local/bin/ctop
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Docker

docker run --rm -ti \
  --name=ctop \
  --volume /var/run/docker.sock:/var/run/docker.sock:ro \
  quay.io/vektorlab/ctop:latest
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Building

Build steps can be found here.

Usage

ctop requires…

But if you run an SELinux-enabled distribution, you'll find that running ctop as the documentation suggests, fails:

docker run --rm -ti \
  --name=ctop \
  --volume /var/run/docker.sock:/var/run/docker.sock:ro \
  quay.io/vektorlab/ctop:latest
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🐳 🐳 🐳

ctop - error ───────
  │                                                                                 │
  │  [12:54:15 UTC] attempting to reconnect...                                      │
  │                                                                                 │
  │  [12:54:16 UTC] Get http://unix.sock/info: dial unix /var/run/docker.sock: con  │
  │  nect: permission denied                                               
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What's going on here? Presumably SELinux is blocking the ctop container's access to information necessary for monitoring the other containers.

The Fix

Luckily, there's a very easy fix for this! You can just run the ctop container in privileged mode:

docker run --privileged --rm -ti  \
  --name=ctop   \
  --volume /var/run/docker.sock:/var/run/docker.sock:ro   quay.io/vektorlab/ctop:latest
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Now you can see all your favorite containers, interact with their log interfaces, dip into their shells, etc:

  ctop - 12:57:42 UTC   8 containers

     NAME        CID         CPU         MEM         NET RX/TX   IO R/W      PIDS

   ◉  bugout_bot… 8f84fe3983…      1%       2M / 944M 19M / 16M   1M / 0B     6
   ◉  bugout_bug… 16f1479be4…      0%       3M / 944M 1M / 1M     6M / 0B     5
   ◉  bugout_gat… fc951914df…      0%       3M / 944M 56M / 35M   256K / 0B   21
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