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If you're running multiple containers of images that are themselves derived from a same image, is it still a one-time cost? Is Docker smart enough to run "only

by rtpg 9y ago

If you're running multiple containers of images that are themselves derived from a same image, is it still a one-time cost? Is Docker smart enough to run "only one" instance of Ubuntu, for example?

stormbrew 9y ago
What resources are you concerned about being consumed? - There will only ever be one running kernel with docker. - The base filesystem layer, if identically hashed, will be shared as an overlay filesystem. - The memory footprint of whatever each container runs (which will generally not be a full from runlevel0 system) will not be shared, except in the sense that binaries loaded into ram from the same overlay filesystem will have some of their disk pages shared.
- kosinus 9y ago
  In practice, the base layers update often, and not all apps will be running from the same version.
  - stormbrew 9y ago
    That's true, but it is something that is potentially within your control as well.
ealexhudson 9y ago
What stormbrew said above. It's probably not an absolutely O(1) cost but in practice I haven't noticed the difference. I definitely have noticed a saving from pushing many different "slim" alpine images around (alpine is not at fault here, but the more differences your images have, the less you get to re-use existing layers).