Unpacking Linux containers: understanding Docker and its alternatives

optimizedbyotto.com

44 points·ottoke··8 comments

Besides FreeBSD jails, there was AIX Workload Partitions, Solaris Zones and HP-UX Vaults.

... and they ALL were (and still are) in production long time before Docker went viral.

Sadly, no mention of ststemd-nspawn. Image management is manual, but it's otherwise a very powerful alternative.

Is it true that Docker is single-threaded (or only allows a single thread)?

I had a guy who ran some of my software once that said it wouldn't work in Docker. My software used several threads. I'm sure that I read somewhere that one of the problems with Docker was that it only allowed single-threaded programs to work.

That is false. Creation of threads/processes is still available within a container. Docker will run the entry point as PID 0 and that process can create as many subprocesses as it wants. If you’re talking about cores, Docker utilizes Linux cgroups which permits usage of multiple cores. You can limit the CPU quota and assign the container to specific cores. See https://docs.docker.com/config/containers/resource_constrain...

Docker is back-doored by design.. false?

Most devs use #Docker or #Podman, but do you really understand what’s happening under the hood? Let’s demystify #Linux #containers in simple, concrete terms. Just a 12-min read!

This is not a hashtag website.

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