public OpenGrok demo - autodeploy on push with successful build and test

[vladak]

As asked in #1736 , there should be a public demo server that indexes OpenGrok code, running the latest master.

[vladak]

Need to sort out these things:

• deploy mechanism (some sort of Github hook ? Travis ? https://docs.travis-ci.com/user/deployment/)
• domain name + registration
• hosting: AWS/Google cloud/Oracle cloud/Heroku ? (who is going to sponsor this ?)

[vladak]

I think Heroku is clear winner as it provides:

• webapp deployment via webapp-runner (https://devcenter.heroku.com/articles/java-webapp-runner)
• domain name (.herokuapp.com)
• deploy via Travis (https://docs.travis-ci.com/user/deployment/heroku/)
• way to run commands after deploy (so that indexer can run)

and is quite cheap ($7/month for Hobby version - https://www.heroku.com/pricing).

[vladak]

According to https://atmos.org/github-services/auto-deployment/ it is not necessary to deploy via Travis. One can deploy from Github directly to Heroku. For that 2 Services are needed:

• Autodeploy - automatically creates deployment Github objects (https://developer.github.com/v3/repos/deployments/#create-a-deployment), can be set so that deployments are created only for successful CI runs ('Deploy on status').
• HerokuBeta - performs the actual app deployment upon seeing new deployment object being created

This seems to be cleaner than deploying via Travis (and does not extend the dependency - Travis can be replaced by different CI in the future) and provides tracking via the deployment objects.

[vladak]

There is demo.opengrok.org however it would be nice to have this more seamless, ideally with ping-back via webhook to see if the deploy was successful.

[vladak]

Given that there is Docker image it would be shame not to use it since it wraps most of the complexity in usable package. Initially my idea was to deploy using the existing Travis pipeline however that is not needed - I stumbled upon https://stackoverflow.com/a/38593838/11582827 that recommends to use https://github.com/containrrr/watchtower that polls Docker image status and restarts existing containers with the latest image.

So, this basically boils down to couple of things:

• finding a provider that can run Docker (ideally for free)
• mapping demo.opengrok.org to the IP of the VPS
• adding functionality to the OpenGrok Docker image to detect incompatible index and reindex from scratch (based on environment variable that would not be set by default)
• making the Docker container to index demo repositories (OpenGrok repo would suffice)
  • maybe even create new Docker image based on the existing OpenGrok image that would do it