feat(Prometheus/ServiceMonitor): add configurable tlsConfig & bearerTokenFile for authentication

[eyenx]

This implements a configurable tlsConfig for the serviceMonitor used to grab metrics from the Vault API.

Additionally it adds the possibility to set a bearerTokenFile for authentication purposes.

[eyenx]

@tvoran @swenson @tomhjp

Anyone able to review this pls? It's kinda sad this is laying around without reaction for more than 3 months.

[dtrts]

I would also like to see this feature added to the chart.

If possible the chance to configure bearerTokenSecret would also be welcomed.

[eyenx]

I would also like to see this feature added to the chart.

If possible the chance to configure bearerTokenSecret would also be welcomed.

Would be nice I know, but HashiCorp does not care about contributions from outsiders. This will be laying around forever or they will implement it by themselves.

[eyenx]

[tomhjp]

Thanks for the PR - I appreciate it's been stuck without feedback for a long time, but if you're still interested I'm happy to help you get this landed. I've triggered the test suite and have a few minor comments but this looks pretty close to merging.

[eyenx]

Thank you @tomhjp will look at it today

[eyenx]

@tomhjp ready for a review :)

[tomhjp]

Hey @eyenx, thanks for your patience. I wanted to try writing a proper integration test that exercised these options for real, I've pushed some WIP in (EDIT) c66c9a2.

One thing I learnt while I was looking deeper is that the bearerTokenFile option is deprecated, with users directed to authorization instead: https://prometheus-operator.dev/docs/operator/api/#monitoring.coreos.com/v1.Endpoint. It does seem like a safer and improved pattern, WDYT about supporting authorization instead of bearerTokenFile in this PR?

[tomhjp]

Merged in #1025 - thanks again!