Connecting to postgres via a socket

For my side projects, I like to share one instance of postgres and connect to it over a socket, rather than fiddling with usernames and passwords or running dockerized postgres for each project or anything like that. If you’ve apt installed your postgres you also don’t have to mess with pg_hba.conf to allow connections unlike with user/pass auth (has that changed since I learned this? I don’t know).

For an elixir project using Ecto, it’s not trivially obvious from the docs how to configure a socket connection rather than user/pass - the diff to config/dev.exs (and matching change to config/test.exs) you’ll want looks like

--- a/config/dev.exs
+++ b/config/dev.exs
@@ -2,9 +2,7 @@ import Config

 # Configure your database
 config :rk, Project.Repo,
-  username: "postgres",
-  password: "postgres",
-  hostname: "localhost",
+  socket_dir: "/var/run/postgresql",
   database: "project_dev",
   stacktrace: true,
   show_sensitive_data_on_connection_error: true,

Posted here so that I won’t need to go hunting around for this again in the future.

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