Adds db check

[pierreozoux]

I use docker compose to start my services.
It was just working 1 time over 4 tries.
This was due to the fact that the db was not ready when the web tried to connect to it.

This PR adds a loop to wait for the db to be ready before trying anything.

It is inspired from: https://github.com/tutumcloud/tutum-docker-wordpress-nosql/blob/master/run.sh

I didn't understand your indentation. Is it one tab of 8 spaces? I can redo the PR to match your codestyle.

Thanks!

Pierre

[pawohl]

• Similar pull request rejected by maintainer in Wait for mysql server to start #1
• needs rebase

[funkyfuture]

it would be great to get this rebased and merged.

yes, startup logic in entrypoint scripts can be a pita, but it's very common in the ecosystem. e.g. to check out an image quickly i use Docker Compose on my desktop machine. however the support for orchestrating startup sequences (which isn't a simple as 'wait x timeunits') was rejected by its maintainers.

[Rillke]

@funkyfuture We forked to uni-halle/etherpad-lite-docker, added support for the here requested feature and added an example docker-compose.yaml file as well as a sample .env among other adjustments we were in need of to use the pre-built image directly from docker hub.

[funkyfuture]

@Rillke good to see other academic institutions to take care of foss and to contribute back. i usually put example compose files into the README as it's rendered on the Docker hub's description page.

[funkyfuture]

oh @Rillke, is there an associated repository on the Docker hub?

[Rillke]

@funkyfuture Repository in docker hub: https://hub.docker.com/r/unihalle/etherpad-lite/