Is it weird that even after completing the tutorial, Docker says that there is no swap file detected?
I am not sure Docker is talking about what you think it is. Check the OS level indicators with
2GB Digital Ocean instance (with 1GB swap for safety)
total used free shared buffers cached Mem: 2002 1748 254 0 121 575 -/+ buffers/cache: 1051 951 Swap: 1023 43 980
2GB Digital Ocean instance (no swap)
total used free shared buffers cached Mem: 2002 1814 188 0 273 627 -/+ buffers/cache: 914 1088 Swap: 0 0 0
and also, CPU resource on cheap VPS is kinda of a luxury thing so just swap for now to be safe.
What is docker referring to?
But docker still says
WARNING: No swap limit support!
It means that it is unable to enforce a limit on amount of swap that the processes running inside the container are using. Either your kernel was compiled with the necessary cgroup (kernel options
MEMCG_SWAP, I believe) or it requires a command line option at boot to enable this feature.
In short, this has nothing to do with the presence of swap space and unless you’re hosting competing containers and must assure available private memory and swap you can safely disregard the message.
Edit: Gentoo has a HOWTO on setting up LXC containers; since Docker is a fancy frontend for LXC, the kernel configuration part of that HOWTO might be helpful:
@sam how about changing this message to “No swap quota support” - not exactly correct, but more likely to leave a correct first impression (i.e. that it’s a nice-to-have)?
It’s not coming from us, we would need to pipe STDERR and process it to fix that, better approach is raising a ticket with Docker to improve the message.
I have the same message, and same
Swap: 0 0 0 today, 2017… It is fine!
Although swap is generally recommended for systems utilizing traditional spinning hard drives, using swap with SSDs can cause issues with hardware degradation over time. Due to this consideration, we do not recommend enabling swap on DigitalOcean or any other provider that utilizes SSD storage. Doing so can impact the reliability of the underlying hardware for you and your neighbors. This guide is provided as reference for users who may have spinning disk systems elsewhere.