I don't get the differentiation between "rkt" and "docker". What complexity does Docker add? Separate networking? Difficulty communicating between processes?
Just trying to understand why rkt is less overhead...
Just trying to understand why rkt is less overhead...
Since then, Docker has improved quite a bit on these so the most in your face practical differences are smaller, but there are still philosophical differences that affects it.
E.g. rkt comes out of CoreOS. CoreOS does a lot around embracing systemd to its full extent. Systemd can provide a lot of the capabilities that Docker did itself, and parts of rkt's design flows from that. E.g. restarting, querying status, capturing the logs, so in a systemd based system, Docker integrated fairly poorly in that systemd would be starting and keeping track of a Docker client rather than the process actually controlling the container, while rkt fits right in.
Again, the difference is getting smaller, and various tools like runc etc. from Docker now allows you narrow the gap even more (if you put in extra effort).
Try both, basically - they're similar enough that it's worth figuring out which "flavor" you like best.
The docker daemon has historically had some stability issues as well as some security implications. Running a command line tool like rkt is a vastly smaller attack surface and less complex stack overall.
You are namespaced, so the linux kernel promises that even though you're root, you're not dangerous, and there is syscall filtering and shit going on.... but that historically has not really fared that well!
But your statement is false. You're root with and without privileged. Privileged gives you back CAPABILITIES which are different than USER, so your claim is bullshit.
That is objectively false.
uid = 0 is "privileged" basically everywhere in the kernel, from filesystem management (reading a file bindmounted in that's owned by root e.g.) to binding to low ports (like 80).
As you can see from the docs, it says "the most important security improvement is that, by default, container processes running as the root user will have expected administrative privilege (with some restrictions) inside the container but will effectively be mapped to an unprivileged uid on the host."
This implies the reverse, that if you don't use userns then your process as root in the container will be mapped to a privilege uid on the host.
This is all I'm saying is true. You clearly don't understand what I'm saying.
This API has to enabled explicitly. Docker daemon works by using a unix socket instead ( "/var/run/docker.sock" ).
> acts more or less like an init for containers
There is Docker daemon and there is Docker CLI. Both have separate scopes.
Docker CLI is glorified curl, everything happens in the daemon (containerd being logically -- but finally not physically -- part of the daemon).
If you'll indulge me putting on my corporate hat for a minute: we've had some customers very happy scheduling a high volume of containers at a high rate on nomad:
- https://www.hashicorp.com/c1m.html (mentions a docker bug even)
- https://www.youtube.com/watch?v=MRtRwhL5lwM
If at all possible I'd recommend using our Java or exec drivers as they use builtin containerization and avoid the overhead of docker or rkt.