Things should not care or mostly even know if they’re being run in docker.
Well, that is boldly assuming:
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that endlessly duplicating services across containers causes no overhead: you probably already have a SQL server, a Redis server, a PHP daemon, a Web server, … but a docker image doesn’t know, and indeed, doesn’t care about redundancy and wasting storage and memory
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that the sum of those individual components work as well and as efficiently as a single (highly-optimized) pooled instance: every service/database in its own container duplicates tight event loops, socket communications, JITs, caches, … instead of pooling it and optimizing globally for the whole server, wasting threads, causing CPU cache misses, missing optimization paths, and increasing CPU load in the process
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that those images are configured according to your actual end-users needs, and not to some packager’s conception of a “typical user”: do you do mailing? A/V calling? collaborative document editing? … Your container probably includes (and runs) those things, and more, whether you want it or not
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that those images are properly tuned for your hardware, by somehow betting on the packager to know in advance (and for every deployment) about your usable memory, storage layout, available cores/threads, baseline load and service prioritization
And this is even before assuming that docker abstractions are free (which they are not)
Most containers don’t package DB servers, Precisely so you don’t have to run 10 different database servers. You can have one Postgres container or whatever. And if it’s a shitty container that DOES package the db, you can always make your own container.
that those images are configured according to your actual end-users needs, and not to some packager’s conception of a “typical user”: do you do mailing? A/V calling? collaborative document editing? … Your container probably includes (and runs) those things, and more, whether you want it or not
that those images are properly tuned for your hardware, by somehow betting on the packager to know in advance (and for every deployment) about your usable memory, storage layout, available cores/threads, baseline load and service prioritization
You can typically configure the software in a docker container just as much as you could if you installed it on your host OS… what are you on about? They’re not locked up little boxes. You can edit the config files, environment variables, whatever you want.
Most containers don’t package DB programs. Precisely so you don’t have to run 10 different database programs. You can have one Postgres container or whatever.
Well, that’s not the case of the official Nextcloud image: https://hub.docker.com/_/nextcloud (it defaults to sqlite which might as well be the reason of so many complaints), and the point about services duplication still holds: https://github.com/docker-library/repo-info/tree/master/repos/nextcloud
You can typically configure the software in a docker container just as much as you could if you installed it on your host OS…
True, but how large do you estimate the intersection of “users using docker by default because it’s convenient” and “users using docker and having the knowledge and putting the effort to fine-tune each and every container, optimizing/rebuilding/recomposing images as needed”?
I’m not saying it’s not feasible, I’m saying that nextcloud’s packaging can be quite tricky due to the breadth of its scope, and by the time you’ve given yourself fair chances for success, you’ve already thrown away most of the convenience docker brings.
