Implement the upstream enhancement
https://github.com/argoproj/argo-cd/issues/20619

Summary

Today secrets such as REDIS_USERNAME are only readable via os.GetEnv() which means we cannot mount secrets from disk.
For some

Motivation

Within some environments I work in we can only mount secrets from disk following gatekeeper policies, this means today I cannot run argocd in these environments as the rules around this block me.

Proposal

Where we are reading secrets today we could either:

Give the env var an alternative _FILEPATH and read the file from there
Have a config file which can be read from using a tool like viper to give users the option.
Potential additional benefits are that when secrets change (such as a redis password rotation) the change can be automatically picked up without needing a pod restart.

Notes

I am happy to start implementing this if people agree, it's more an RFP before putting in the work