Setting a different username on the image fails

[maxboone]

Bug report

• I confirm this is a bug with Supabase, not with my own application.
• I confirm I have searched the Docs, GitHub Discussions, and Discord.

Describe the bug

When a different username is passed using POSTGRES_USER the container will exit as the user doesn't exist:

docker run \        
-e POSTGRES_PASSWORD=custom \
-e POSTGRES_USER=custom \
-e POSTGRES_DB=custom \
supabase/postgres
...
server started
psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL:  Peer authentication failed for user "custom"
[local] 2023-06-26 10:09:42.844 UTC [68] custom@postgres LOG:  provided user name (custom) and authenticated user name (postgres) do not match
[local] 2023-06-26 10:09:42.844 UTC [68] custom@postgres FATAL:  Peer authentication failed for user "custom"
[local] 2023-06-26 10:09:42.844 UTC [68] custom@postgres DETAIL:  Connection matched pg_hba.conf line 83: "local  all  all    peer"
Error: exit status 2

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

docker run \      
-e POSTGRES_PASSWORD=custom \
-e POSTGRES_USER=custom \
-e POSTGRES_DB=custom \
supabase/postgres

Expected behavior

Database & user are created with passed environment variables

Screenshots

NA

System information

NA

Additional context

NA

[maxboone]

Main difference that "causes" this is that the base image doesn't use peer authentication for local executed commands, but rather trusts anything that comes from the unix domain.

Possible fix would be to add something in the entrypoint that appends the postgres → $POSTGRES_USER mapping to pg_ident if $POSTGRES_USER != postgres. I'd gladly write this and do a PR but not sure if opinions differ on that approach.