MariaDB not working properly with Django 3.0

[lpulley]

In the django3 branch, I've configured docker-compose.yml to use MariaDB instead of MongoDB, since MariaDB is now officially supported through the mysql stuff in Django, and Djongo appears to not work on Django 3.0 yet. Would be nice to move to first-party-supported databases anyway.

However, MariaDB takes some time to initialize itself on first start, and the project needs to be restarted before Django properly connects to it. I don't think the solution for this is bash scripts; there should be a clean first-party Docker/MariaDB/Django solution to this. I can look further into this over winter break.

[lpulley]

Actually, in its current state, it seems that Django can't connect at all to MariaDB. This definitely needs work and it's my top priority when I get time for this.

[lpulley]

MariaDB's Docker documentation seems to be aware of this issue.

[mgale456]

This stackexchange answer by Thalik got me hopeful for a simple first party thing in docker-compose.yml. Apparently what he does in his docker-compose.yml is no longer supported.

This lead me to read the docker-compose file documentation. The section for depends_on lead me to this page, which is about controlling startup order.

TL;DR Docker says it is best to have a resilient app that checks and reconnects itself if the db doesn't connect, but something like wait-for-it.sh is a decent alternative if you don't need that resilience

Also, I haven't searched much at all for ways to do this in Django, but I didn't find it at a glance.

[lpulley]

Yeah, it does sound like having Django do this would be the cleanest way. I'll look into have it retry the database connection.

[lpulley]

This one might not retry enough but seems like a clean solution if it does work: https://github.com/udemy/django-dbconn-retry

Can install with requirements.txt and INSTALLED_APPS.

[mgale456]

I tried that app, and it did not fix the startup. I also reverted that commit, so you can go back and see them if you want.

In browsing for another potential solution for this, I saw that it is the runserver command that is halting. We may want to see how Daphne handles startup, and it if hang up on the same db checks

[lpulley]

I've found that PostgreSQL takes a few seconds to initialize instead of a minute. Seems like PostgreSQL has the "cool kid" factor too, might be something we want to use for this project, especially if it plays more nicely with Docker.

[mgale456]

PostgreSQL seems to be supported by core Django unlike MongoDB was, so it seems like a fine candidate to me. idk anything else about it, and I'm not sure if there could really be any problems caused by it, since it is also a full featured database afaik.

If it improves our setup instructions by 2 steps, I'm all in. That's very nice for the future ease of CoGS.