TIL: Some Docker & Linux

My Linux & docker background

I’ve been setting up my dev environment on a Linux machine, and I’m a relative noob to Linux, I know enough to get shit done, but given the option, I’d rather Windows or Mac. Basically here because I have no option. Same with containers/docker, I’ve been pretty much staying away from those unless I had no option.

I had a very good primers though, did a little bit of Linux Essentials certification sometime in 2015/16, thanks to Kapil.

I followed that up with Brian Holt’s Complete Intro to Containers (feat. Docker). Check out Brian Holt & Jem Young on Frontendmasters if you’re a frontender trying to learn more Linux & backend - they’ve been good to me.


Docker Compose

  • Makes it easy to get your multiple container application going.
  • Works in all environments, staging, development, production, testing, & CI.
  • You define your application in a docker-compose.yml file.
  • docker compose up will start & run your application
    • you can also specify the services you want to run, just pass them as extra arguments like so: docker compose up service1 service2

Docker system prune

Remove all unused containers, networks, images (both dangling and unreferenced), and optionally, volumes.

Okay but how does it determine what’s unused?

unused in this context means “the container isn’t running”


Graphics - Wayland & X

I’m running the latest Ubuntu LTS (22.04). Now, this uses a 3D graphics rendering engine to power your UI, and that’s called Wayland. In the past, Ubuntu used X, which is a 2D engine.

Wayland seems to be powering Ubuntu by default, but Ubuntu still ships with X, for backwards compatibility, and as a fallback.

The problem: I installed a Slack & Edge (via their debian packages) and they just wouldn’t launch.

The fix: Disabling wayland & switching to X did the trick. They’ve been launching fine since. And I haven’t felr like I’m losing out on anything around the rest of the UI.

User Groups

User groups are a way of managing permissions. The most useful usecase I’ve seen for them is the following scenario:

Single dev on a machine, there’s certain tasks I’m guaranteed to do everytime I’m on the machine, such as running docker containers. Docker commands need root permission, so you have to sudo docker ... everytime you’re doing anything docker related, which can be a waste of time.

If you add your user to the docker group (created automatically, when you install docker), you won’t have to sudo anymore. Handy trick I was first taught by Brian Holt.

Linode has beautiful docs on User Groups, good reference.


Low level util that does a lot of stuff, seems best suited to long running processes

systemd is a Linux initialization system and service manager that includes features like on-demand starting of daemons, mount and automount point maintenance, snapshot support, and processes tracking using Linux control groups.

systemd not only manages system initialization, but also provides alternatives for other well known utilities, like cron and syslog.

Again, Linode docs for reference