feat: psql flake

flake.nix

@@ -1,7 +1,9 @@
 {
   description = "nix flakes";
 
-  outputs = {self}: {
+  outputs =
+    { self }:
+    {
       templates = {
         c = {
           path = ./c;
@@ -23,6 +25,10 @@
           path = ./odin;
           description = "odin template";
         };
+        psql = {
+          path = ./psql;
+          description = "psql template";
+        };
         crystal = {
           path = ./crystal;
           description = "crystal template";

psql/.envrc

@@ -0,0 +1 @@
+use flake

psql/.gitignore

@@ -0,0 +1 @@
+.postgres*

psql/flake.nix

@@ -0,0 +1,57 @@
+{
+  # original via @estebxn
+  description = "Tiny PostgreSQL flake";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs =
+    { nixpkgs, ... }:
+    let
+      system = "x86_64-linux";
+      pkgs = import nixpkgs { inherit system; };
+      pg = pkgs.postgresql_16;
+    in
+    {
+      apps.${system}.default = {
+        type = "app";
+        program = toString (
+          pkgs.writeShellScript "run-postgres" ''
+            set -euo pipefail
+
+            : ''${PGDATA:=$PWD/.postgres}
+            : ''${PGHOST:=$PWD/.postgres-socket}
+            : ''${PGPORT:=5432}
+            : ''${PGUSER:=postgres}
+            : ''${PGDATABASE:=app}
+
+            mkdir -p "$PGHOST"
+
+            if [ ! -d "$PGDATA" ]; then
+              ${pg}/bin/initdb -D "$PGDATA" --auth=trust --username="$PGUSER"
+              cat >> "$PGDATA/postgresql.conf" <<EOF
+            listen_addresses = '127.0.0.1'
+            port = $PGPORT
+            unix_socket_directories = '$PGHOST'
+            EOF
+            fi
+
+            ${pg}/bin/pg_ctl -D "$PGDATA" -l "$PGDATA/postgres.log" start
+            trap '${pg}/bin/pg_ctl -D "$PGDATA" stop' EXIT
+
+            until ${pg}/bin/pg_isready -h "$PGHOST" -p "$PGPORT" >/dev/null 2>&1; do
+              sleep 1
+            done
+
+            ${pg}/bin/psql -h "$PGHOST" -p "$PGPORT" -U "$PGUSER" postgres \
+              -tc "SELECT 1 FROM pg_database WHERE datname = '$PGDATABASE'" \
+              | grep -q 1 || ${pg}/bin/createdb -h "$PGHOST" -p "$PGPORT" -U "$PGUSER" "$PGDATABASE"
+
+            echo "Postgres is running on port $PGPORT"
+            echo "psql -h $PGHOST -p $PGPORT -U $PGUSER $PGDATABASE"
+
+            while true; do sleep 60; done
+          ''
+        );
+      };
+    };
+}