I never understood how to use Docker, what makes it so special? I would really like to use it on my Rapsberry Pi 3 Model B+ to ease the setup process of selfhosting different things.
I’m currently running these things without Docker:
- Mumble server with a Discord bridge and a music bot
- Maubot, a plugin-based Matrix bot
- FTP server
- Two Discord Music bots
All of these things are running as systemd services in the background. Should I change this? A lot of the things I’m hosting offer Docker images.
It would also be great if someone could give me a quick-start guide for Docker. Thanks in advance!
IMHO with docker and containerization in general you are trading drive space for consistency and relative simplicity.
a hypothetical:
You set up your mumble server and it requires the leftpad 3.7 package to run. you install it and everything is fine.
Now you install your ftp server but it needs leftpad 5.5. what do you do? hope the function that mumble uses in 3.7 still exists in 5.5? run each app in its own venv?
Docker and containerization resolve this by running each app in its own mini virtual machine. A container running mumble and leftpad 3.7 can coexist on host that also has a container running a ftp server with leftpad 5.5.
Here is a good video on what hole docker and containerization looks to fill
https://www.youtube.com/watch?v=Nm1tfmZDqo8
Doesn’t that mean that docker containers use up much more resources since you’re installing numerous instances & versions of each program like mumble and leftpad?
Kinda, but it depends on the size of the dependencies, with drive space bing so cheap these days do you really worry about 50Mb of storage being wasted on 4 different versions of glib or leftpad
Docker containers aren’t running in a virtual machine. They’re running what amounts to a fancy chroot jail… It’s just an isolated environment that takes advantage of several kernel security features to make software running inside the environment think everything is normal despite being locked down.
This is a very important distinction because it means that docker containers are very light weight compared to a VM. They use but a fraction of the resources a VM would and can be brought up and down in milliseconds since there’s no hardware to emulate.
To put it in simpler terms, I’d say that containers virtualise only the operating system rather than the whole underlying machine.I guess not then.