A flake to create an environment-local postgreSQL database

This flake provides a set of commands to set up and work with a postgres database inside a specific folder, without any need to install/configure any containers.

How to use

When launching the dev-shell

nix develop github:hermann-p/nix-postgres-dev-db

there will be three commands available. All commands need an environment variable $PG_ROOT set, else they will fail saying so.

• start-database launches a postgres server keeping all data in $PG_ROOT. If there is no postgreSQL-folder at that location, everything will be set up and three databases will be created, named dev, test and whatever $USER is set to. Note it will try to bind to port 5432 and fail if that port is not available.
• stop-database stops the postgres server at $PG_ROOT. If it fails it tries to remove stale lock files from there.
• psql-wrapped is just psql set up with the correct port and host parameters to access the local postgres server.

Use it in your dev shell

To use the convenience setup for your own dev env, you will need to import the three commands seperately. Don't forget to provide your desired postgres version in buildInputs!
Something like the following flake.nix will work:

{
  inputs = {
    utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    nixpkgs.inputs.nixpkgs.follows = "nixpkgs";
    devDB.url = "github:hermann-p/nix-postgres-dev-db";
    devDB.inputs.nixpkgs.follows = "nixpkgs";
  };
  outputs = { self, nixpkgs, utils, devDB }:
    utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
        db = devDB.outputs.packages.${system};
      in {
        devShell = with pkgs;
          mkShell {
            buildInputs = [
              postgresql_15
              db.start-database
              db.stop-database
              db.psql-wrapped
            ];
            shellHook = ''
              export PG_ROOT=$(git rev-parse --show-toplevel)
            '';
          };

      });
}