Add a `POSTGRES_HOST` variable to backend deployment

[ohaiwalt]

This can be created preemptively until the backend actually supports it.

The operationcode_backend has its Postgres host hardcoded per environment, which makes it very difficult to create N number of environments for any given purpose.

[sethbergman]

This may be of use to you:
https://github.com/next-stack/stolon-chart/blob/master/stolon/templates/NOTES.txt

[ohaiwalt]

@sethbergman The issue is that the database host cannot be specified at runtime, as it's hardcoded. Can you expand on how that link would help?

[sethbergman]

I am not 100% sure, but the way the repo is setup seems to be the key. This may provide more clarity:
https://github.com/next-stack/stolon-chart/blob/master/stolon/README.md

[ohaiwalt]

Stolon, and particularly the Stolon Helm chart, are for running databases in containers, which is orthogonal to this issue. It doesn't matter where the database is running, we still need to be able to configure its hostname in in the application.

[sethbergman]

Ahh I see. Thank you for clarifying. I'm still learning HELM and kubernetes. 😃

[sethbergman]

It seems that there may be a solution here:
https://chat.stackexchange.com/rooms/56392/discussion-between-ypercube-and-davidechicco-it which is a continued discussion from this question:
https://dba.stackexchange.com/questions/168793/postgresql-what-is-the-hostname-address-of-my-default-database

[ohaiwalt]

@sethbergman you're overthinking it. This issue requests an environment variable be added to the deployment.yml file for the OpCode backend, in order for the backend application to make use of that to find its database. Very simple, 3-4 line change, would look like all the other environment variables present in the deployment.yml