nixos/hosts/common/optional/docker/postgres.nix

{ pkgs, lib, inputs, config, ... }:
let
  admin_dbPasswordFile = lib.optionalString (lib.hasAttr "sops-nix" inputs) config.sops.secrets."software/postgres/admin_db/password".path;
in
{
  sops.secrets = {
    "software/postgres/admin_db/password" = { };
  };
  virtualisation.arion = {
    backend = "docker";
    projects = {
      "db".settings.services."db".service = {
        restart = "unless-stopped";
        build.context = "/nix/store";
        build.dockerfile = builtins.baseNameOf "${pkgs.writeScript "pgDockerfile" ''
            FROM postgres:16
            # install packages
            RUN apt-get update \
                && apt-get install -y --no-install-recommends \
                    postgresql-16-postgis \
                    jq \
                && rm -rf /var/lib/apt/lists/*
          ''}";
        environment = {
          POSTGRES_PASSWORD_FILE = admin_dbPasswordFile;
          POSTGRES_USER = "admin";
          POSTGRES_DB = "admin_db";
          PGDATA = "/var/lib/postgresql/data/pgdata";
          POSTGRES_MULTIPLE_DATABASES = ''
            [
              {
                "osm": {
                  "user": "gis",
                  "extensions": [
                    "hstore",
                    "postgis"
                  ]
                },
                "bitcoin": {
                  "user": "satoshi",
                  "extensions": []
                },
                "btc_models": {
                  "user": "dbt",
                  "extensions": []
                },
                "dev_btc_models": {
                  "user": "dbt",
                  "extensions": []
                }
                "test": {
                  "user": "test",
                  "extensions": [hstore]
                }
              }
            ]
          '';
        };
        ports = [ "5432:5432" ];
        volumes = [
          "/mnt/postgres:/var/lib/postgresql/data"

          # Need to mount secret file 
          "${admin_dbPasswordFile}:${admin_dbPasswordFile}"

          # PG init script to parse json specified in POSTGRES_MULTIPLE_DATABASES
          # creates databases, users and installs extensions for each database.
          "${pkgs.writeScript "init.sh" ''
            #!/bin/bash
            function create_user_and_database() {
              local database=$1
              local user=$2
              local extensions=$3
              echo "### admin user: $POSTGRES_USER ###"
              echo "  Creating database '$database'"
              echo "  Creating user  '$user'"
              psql -v --username "$POSTGRES_USER" -d "$POSTGRES_DB" <<-EOSQL
                  CREATE USER $user;
                  CREATE DATABASE $database;
                  GRANT ALL PRIVILEGES ON DATABASE $database TO $user;
            EOSQL
            
            # Loop through extensions and create them
            for ext in $(echo "$extensions" | tr ',' ' '); do
              echo "     - Installing extention $ext"
              psql -v --username "$POSTGRES_USER" -d "$database" -c "CREATE EXTENSION $ext;"
            done
            }
            
            if [ -n "$POSTGRES_MULTIPLE_DATABASES" ]; then
            
              # Parse the JSON string
              database_names=$(echo "$POSTGRES_MULTIPLE_DATABASES" | jq -r '.[0] | keys[]')
              echo "Multiple database creation requested: $(echo "$database_names" | tr "\n" " ")"
              
              # Loop through each database and create it
              for db_name in $database_names; do
                user=$(echo "$POSTGRES_MULTIPLE_DATABASES" | jq -r ".[0] | .''${db_name} | .user")
                extensions=$(echo "$POSTGRES_MULTIPLE_DATABASES" | jq -r ".[0] | .''${db_name} | .extensions | join(\",\")")
                create_user_and_database "$db_name" "$user" "$extensions"
              done
            fi
           ''}:/docker-entrypoint-initdb.d/init.sh"
        ];
      };
    };
  };
}