ctop – top-like interface for monitoring Docker containers

ctop is a very simple, but very useful tool for when you run a number of Docker containers and want to have a top-like overview of their CPU, memory, and network usage.

This article provides more details on how to install, run, and use ctop effectively, including container filtering, single container view, etc.

dive – Docker image explorer

dive is a Docker image explorer. This is a very handy tool when you are trying to figure out how a Docker image was built and what’s in it, and you don’t have the original Dockerfile.

It uses the meta information for each layer to show you which command was used to create the layer, and which files were added, removed, or changed.

Additionally, you can use dive to make sure your Docker images are optimized and their size is under control. You can even integrate dive into your CI/CD pipeline!

Fedora 31: Docker Fix

I’ve updated my laptop to Fedora 31 over the Christmas holidays. Pretty much everything works as it did before. Except for Docker, which suddenly fails to start the service.

A quick Google search pointed to the discussion in this bug report, where I found the solution that worked for me:

  1. Edit /etc/sysconfig/grub
  2. Append systemd.unified_cgroup_hierarchy=0 to the GRUB_CMDLINE_LINUX variable
  3. Run “grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
  4. Reboot

Once the machine came back up gambling bitcoin, docker service was running normally.

Lazydocker – a simple terminal UI for both docker and docker-compose

Lazydocker is a simple terminal UI for easier management of Docker. This is particularly useful for new Docker users, but can as well save plenty of keystrokes to the seasoned administrators.

Container misconceptions

Ricard Bejarano points out a few container misconceptions. I particular like the bit about Swarm as a better option than Kubernetes for individual projects and small setups (1-2 nodes):

Swarm is Docker, Inc.’s orchestrator. It started development five years ago. It’s built into the Docker Engine, which makes it the same to run it on development machines as in production servers.
In my opinion, it is much less powerful than Kubernetes, and I would vote against using it in a business environment.
That said, I’m a happy admin of a single-node Swarm running all of my personal services at home. But that’s it. I wouldn’t use it for anything with more than 1-2 nodes, but for those applications, I feel is the right tool for the job.