feat: add support for custom initContainers

[hqdncw]

Description

Adding custom initialization containers gives users more fine-grained control over their deployments. Adding custom initContainers is possible in Bitnami charts as well.

One example use-case is ensuring that another service is available.

TODO

• Add unit tests

[james-d-elliott]

Thanks for choosing to contribute! We don't currently unit test the charts as we have not invested time into that, you're welcome to skip it if you want. Otherwise we can probably assist with this if you have a particular unit testing tool you are familiar with.

One comment I'd add is I'm not too sure if it's better as is or better to limit the rendering to the elements that exist within the spec, rather than just arbitrarily rendering values the user adds. There are benefits to both (i.e. one shows an error the other silently ignores it).

Also you'll need to sign the DCO: https://www.authelia.com/contributing/guidelines/commit-message/#developer-certificate-of-origin

[ajgon]

Hey @uid54289 , thank you very much for this. Since, you're implementing this - can you also add support for sidecar containers as well? These can be super-handy for tools like k8s-sidecars.

[thomaspetit]

Any update on this feature? :) Might wanna look into it myself as I want to be able to create users_database.yml file (bounded to a PVC).

[james-d-elliott]

Taken over in #230