I am looking for a good tutorial on how to move a current Nextcloud instance (NC 20, Ubuntu 14 LTS) to Docker. It is important that the local data folder is kept. The (mySQL) database should then also disappear a (different?) Docker container.
Since I have never worked with Docker, I am also not clear how I get after an update (ie the re-installation of a container) all apps, etc. again without installing this manually?
Is there a good tutorial on this (for a Docker beginner)?
it is always good idea to start with official docs. there is pretty comprehensive guide how to migrate to another server.
same applies for docker. this one is not actually a guide but one can start… but there are tons of get Nextcloud running for dummies for every technology one can imagine… Docker itself is not such different from another hardware but it has some special habits especially in in terms how one configure the system - user right mapping for files and running commands within containers confuse lot of beginners…
I would recommend you to setup a playground instance first look around how to setup it, create some files, backup, brake and restore it… once you get familiar you can move your existing installation there… great advantage of docker you can run lot of independent Nextcloud instances in parallel - e.g. one for testing/playing and another one for production… I run two where I test new apps and upgrade without touching my productive instance - the only shared resource is the entry point reverse proxy traefik which is happily serving both instances and doing all the heavy work with letsencrypt certificates, header rewriting and so on…