Research way to keep content when updating a dockerimage

[stoerr]

We have a docker image to run Composum, which could be modified to run production systems. When you want to run a production system with that, we would need a nice clean way to keep the JCR content and possibly configuration. Describe and test ways to do that.

[stoerr]

That might be an approach for internal testing systems, too, though that is not quite clear. There are 3 ways to deploy a system:

• via package manager. For internal systems this can be done every time, after each push.
• via features. That needs restarting the system and is thus more complicated.
• via exchanging the whole system (e.g. as docker image). That needs a docker registry and is thus likely more infrequent, or has to be done through an internal docker registry (which might be OK, Sonatype Nexus Repository Manager supports that).

[stoerr]

@ist-rw :

Discussion of variants and a summary is in https://github.com/ist-dresden/composum-launch/blob/develop/documentation/PermanentDockerSystem.md (permalink to current version https://github.com/ist-dresden/composum-launch/blob/62e514de87ad32281e440a74dc6b88518f6c6055/documentation/PermanentDockerSystem.md ). I did some tests and don't see a principal problem using docker for hosting the various environments, but of course that depends on the provider. Excerpt from that:

Test results:

• permanency of JCR works without problems when mounted from an external volume
• Package updated in docker container -> is updated on restart in the system
• configuration: changed configurations are saved in the JCR and are updated in felix when the new container is started.
• Added packages are saved in JCR, incl. bundles -> permanent, too.

Open points

1. The test system is used for daily deployments through the "Develop - Build and Deploy Snapshot" jobs. That is so far done using the package manager. Replacing this through building a (850MB) new docker image each time is probably not a good idea -> can, however be combined by continuing with package manager here and replacing the docker image once in a while.
2. Where to store the (due to the non public projects) internal docker images? Possible solutions:
   • https://repo.ist-software.com/ can be configured for docker images
   • solve licensing topic and make them public
3. Where / how are /opt/sling/launcher/repository and /opt/sling/launcher/logs stored? -> depends on the provider hosting the server.