Build modmailbot and host on docker hub

[randyhoover]

As a user of modmailbot I don't want to have to clone the source and then create my own dockerfile, or copy a created one in. I want to be able to just pull down the newest version of modmailbot with my configuration file mounted, and my logs and other things mounted so I can quickly and easily upgrade the version.

Detailed Description

The bot should have some sort of CI build process to build/test the image to ensure it works, then on a tagged release it should upload to the dockerhub public registry and be tagged as latest and as a specific version (IE 2.28.0)

Context

This change is important for me as it'll allow ease of deployment and upgrades as long as migrations and other things are handled properly. This will allow other users to easily deploy the bot with basic minimal configuration options quite easily.

Possible Implementation

• Could link with DockerHub and do auto-building from there.
• Could use github actions to do the build and release to docker-hub.
• Could use travis-ci since this an open source project.
• Could use gitlab-ci to handle the build and upload part.

Your Environment

• Version used: 2.28.0
• Operating System and version: Ubuntu Linux 18.04
• Docker Version: 18.06.0-ce

Additional Information

I'm more than happy to help create the Dockerfile, the documentation, and docker-compose.yaml necessary to facilitate most of that work. But I think if it is going to be released on the docker hub it should be owned by the project owner and not me.

[LynnAU]

A bit late to this issue, I've already gone through this process for my fork that I update every so often. I build the base image, then another image with the specified configuration and changes like postgres support.

I'm happy to have my jenkins pipeline watch this repo and build with an appropriate pipeline script, then push to dockerhub.

[randyhoover]

While I don't inherently think that's a bad idea, docker hub does offer building/hosting for free if the project owner links it with their GitHub repository, which I think would be a better idea. (I've updated my original issue with that as the first implementation suggestion.

[angeloanan]

Now that we have GitHub Packages, wouldn't it make much more sense if we are publishing it there?