Publish a Zino Docker image

[lunkwill42]

As suggested by the NORDUnet Networking Monitoring WG, a Docker image to run Zino should be published, for ease of installation (for some users).

Instructions for how to use must also be published.

[hmpf]

I'm thinking it should be a base image, since it needs a minimum of two settings files. Otherwise we need some other clever method for getting those settings files to where they are needed. I'm guessing zino.toml won't change often but the two others needs to be updatable somehow, I don't know how acceptable it is to copy files into a running image.

Maybe have a mounted settings volume?

[lunkwill42]

Not sure what you mean by "base image".

The image should be runnable, but since Zino requires at least a secrets file to run (and can really do no good without polldevs.conf), I would suggest the image should expect a bind mount for a "working directory", where the config files should be placed. Remember, Zino also needs to store its running state in a file, and also needs a directory to dump evicted events from its running state.

The Dockerfile itself should do a basic two-phase build, so the resulting image is as small as possible (no need for lots of development dependencies in a production image).

Additionally, it would be preferable that we add a Github workflow (like the one we use in Argus) that will trigger on each Zino release to build and publish an official image to ghcr.io - so that the official instructions for testing Zino with only Docker on your system could be something as simple as like docker run -v $PWD:/zino ghcr.io/uninett/zino:2.2.1

Sub-issues might be in order to split this task into

1. Make a working image definition
2. Make a workflow to publish the image on release triggers
3. Add documentation on how to use it.