Good afternoon! Newbie here, I’ve tried to install Lemmy using Ansible (Debian stable) and I ended up having an issue with the Postgresql connectivity (localhost via socket).

The error message I have is:

thread 'main' panicked at 'Error connecting to postgresql:///lemmy?user=lemmy&host=/var/run/postgresql: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: No such file or directory

I have updated my /etc/postgresql/15/main/pg_hba.conf from peer to trust to md5 with no success (rebooting Postresql each time).

My config.hjson is:

database: {
 uri: "postgresql:///lemmy?user=lemmy&host=/var/run/postgresql"
 password: "{{ postgres\_password }}"
}

Any idea / suggestion? Thanks!

PS: cross-posted on the Matrix.org install support chat

  • idefixOP
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    11 months ago

    My investigations so far have led me to the conclusion that the Ansible install creates multiple docker containers, including one for Lemmy and one for Postgresql. I need now to figure out how inter-container communications work but the host itself is not used.

    • taaz@biglemmowski.win
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      11 months ago

      Ah right, I assumed you were trying to connect the lemmy container to postgres running outside of docker.

      One important thing to remember with all docker compose files - the service name (the first keys in the services: configuration) is also the hostname of that container so to ping lemmy (from some other container in that docker compose) you would do ping lemmy, same for postgres ping postgres - but if the postgres service was named db0 then it would be ping db0.
      You also do not have to expose ports - all containers in that compose share one network (exposing is for outside access).
      All together your postgres config for lemmy should like this:

       database: { 
        # name of the postgres database for lemmy
        database: "lemmy" 
        # username to connect to postgres 
        user: "postgres"
        # password to connect to postgres
        password: "xxxxxxx"
        # host where postgres is running
        host: "postgres" 
        # port where postgres can be accessed
        port: 5432
        # maximum number of active sql connections
        pool_size: 10
      }
      
      • idefixOP
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        11 months ago

        Ok, the good news is that it works. The bad news is that I don’t understand what changed. 🤨

        • taaz@biglemmowski.win
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          11 months ago

          I don’t get what you mean here. Communication over (linux) socket file and TCP/IP is very different.

          • idefixOP
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            11 months ago

            After reading your comment, I went back to investigate my install. I can’t remember having changed anything relevant but Lemmy started to function properly, connecting as it should the database. It’s been stable since, even after reboots.

            As you suggested, I am using “postgres” as the host, as the service is described in the docker-compose.yml file. The communication is then via TCP/IP and not socket.