To anyone that hasn’t yet seen the movie Idiocracy, watch it now. Best documentary you’ll ever watch.

CyberArk is a commercial product that attacks this problem space. It puts an agent process on the host next to your app. Only processes whose fingerprint matches those authorized to access a credential are allowed to fetch it. That fingerprint can be based on the host (known list of production hosts), the os user ID that owns the pid, the path to the executable for the pid, and probably a few more items.

Under that model your app just needs to know the environment that it wants (inject however you want) and the userid it wants to use. At runtime it reaches out to the local cyberark agent to obtain the password secret.