Anyone with experience using NixOS to create a Lemmy instance, please share any caveats and troubleshooting tips you have.

  • neoney@lemmy.neoney.dev
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    1 year ago

    Okay, I’ve actually figured simplifying it out, it’s not that bad. Let me share my config:

    First, since the PR isn’t in nixos-unstable yet, I’m adding the fork as a flake input

    inputs = {
      nixpkgs-lemmy.url = "github:CobaltCause/nixpkgs/lemmy-module-improvements";
    };
    

    then, in my system configuration, I add this:

    # Not sure if this is required, maybe caddy auto-allows it
    networking.firewall.interfaces.eth0.allowedTCPPorts = [443 80];
    
    # Override the lemmy module with the one from the PR
    disabledModules = ["services/web-apps/lemmy.nix"];
    imports = [
      "${inputs.nixpkgs-lemmy}/nixos/modules/services/web-apps/lemmy.nix"
    ];
    
    services.lemmy = {
      database.createLocally = true;
      database.uri = "postgres:///lemmy?host=/run/postgresql&user=lemmy";
      enable = true;
      settings = {
        hostname = "<YOUR_HOSTNAME>";
      };
      caddy.enable = true;
    };
    

    and, that’s it!
    However, I’m not sure if it will cleanly deploy, as you might get an error while starting.
    If so, please check postgresql logs sudo journalctl -fu postgresql. The error will most likely be something like this:
    […] [10289] ERROR: permission denied: "RI_ConstraintTrigger_a_16639" is a system trigger […]

    If that happens, you need to manually run the migration until the fix is merged into Lemmy. Here’s how I did it:

    1. sudo su - postgres
    2. psql -v ON_ERROR_STOP=1 lemmy postgres
    3. (in psql) SET ROLE lemmy;
    4. Paste the SQL code from here: https://github.com/LemmyNet/lemmy/issues/2784#issuecomment-1578337686

    After that’s done, you can exit the postgres CLI by typing \q, exit the postgres user and just simply sudo systemctl restart lemmy which should start properly now, and be accessible to the outside network.
    Open it and it will give you the initial setup screen. Good luck!

    • neoney@lemmy.neoney.dev
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      1 year ago

      Note that the PR got merged into nixpkgs now, but hasn’t made it’s way forward (see https://nixpk.gs/pr-tracker.html?pr=236295), so that’s why you need to do the override for now Also, a fix for the issue with the migrations (if still occuring) has been merged yesterday, but it’s not in any release yet, and especially not in nixpkgs. You could most likely get around it by using overrideAttrs to change the source to make it build from a newer commit.

      • ericjmorey@lemmy.worldOP
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        1 year ago

        Is this sort of lag the nature of package managers that will inherently be part of NixOS and nixpk?

        • neoney@lemmy.neoney.dev
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          1 year ago

          While we were talking I updated lemmy-server using overrideAttrs for my own use. It’s honestly not that hard. You change the commit, specify some random incorrect hashes, build it, nix screams at you that the hash is incorrect (and generously provides the correct one), put the correct hash, and build again. Done.