From 638c4d62abd060cb6aab8adfafb57ed1c30c315f Mon Sep 17 00:00:00 2001
From: Joshua Potter <jrpotter2112@gmail.com>
Date: Sun, 26 Nov 2023 15:44:53 -0700
Subject: [PATCH] Add postgres spec.

---
 specs/postgres/runner               |  3 +++
 specs/postgres/template/.envrc      |  3 +++
 specs/postgres/template/README.md   | 27 +++++++++++++++++++++++
 specs/postgres/template/default.nix | 10 +++++++++
 specs/postgres/template/flake.nix   | 34 +++++++++++++++++++++++++++++
 5 files changed, 77 insertions(+)
 create mode 100755 specs/postgres/runner
 create mode 100644 specs/postgres/template/.envrc
 create mode 100644 specs/postgres/template/README.md
 create mode 100644 specs/postgres/template/default.nix
 create mode 100644 specs/postgres/template/flake.nix

diff --git a/specs/postgres/runner b/specs/postgres/runner
new file mode 100755
index 0000000..e423c2c
--- /dev/null
+++ b/specs/postgres/runner
@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+cp -r template/. "$OUT"
diff --git a/specs/postgres/template/.envrc b/specs/postgres/template/.envrc
new file mode 100644
index 0000000..b9238c3
--- /dev/null
+++ b/specs/postgres/template/.envrc
@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+use flake
diff --git a/specs/postgres/template/README.md b/specs/postgres/template/README.md
new file mode 100644
index 0000000..05fc50b
--- /dev/null
+++ b/specs/postgres/template/README.md
@@ -0,0 +1,27 @@
+# Postgres Flake Template
+
+This is a template for constructing a working environment for local
+[Postgres](https://www.postgresql.org/) (version 15.5) usage. [direnv](https://direnv.net/)
+can be used to a launch a dev shell upon entering this directory (refer to
+`.envrc`). Otherwise run via:
+```bash
+$> nix develop
+```
+
+## Quickstart
+
+To begin, create a new database:
+```bash
+pg_ctl initdb
+```
+If the flake's default `devShell` is loaded, this will create a database cluster
+at `$PWD/data`. To start the database, run the following:
+```bash
+pg_ctl start -o --unix_socket_directories="$PGDATA"
+```
+To shut the database down, run:
+```bash
+pg_ctl stop
+```
+You can also specify a different location for the database cluster using the
+`-D` option in each of the above commands.
diff --git a/specs/postgres/template/default.nix b/specs/postgres/template/default.nix
new file mode 100644
index 0000000..f620865
--- /dev/null
+++ b/specs/postgres/template/default.nix
@@ -0,0 +1,10 @@
+(import
+  (
+    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = lock.nodes.flake-compat.locked.url or "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  { src = ./.; }
+).defaultNix
diff --git a/specs/postgres/template/flake.nix b/specs/postgres/template/flake.nix
new file mode 100644
index 0000000..7ed71d3
--- /dev/null
+++ b/specs/postgres/template/flake.nix
@@ -0,0 +1,34 @@
+{
+  description = ''
+    An opinionated postgres flake.
+
+    To generate a copy of this template elsewhere, run:
+    $> bootstrap postgres
+  '';
+
+  inputs = {
+    flake-compat.url = "https://flakehub.com/f/edolstra/flake-compat/1.tar.gz";
+    flake-utils.url = "github:numtide/flake-utils";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            postgresql_15
+          ];
+          shellHook = ''
+            # The server will try to use the data directory named by this
+            # environment variable whenever `-D` is not specified (for e.g.
+            # `postgres` and `pg_ctl`).
+            # https://www.postgresql.org/docs/15/server-start.html
+            export PGDATA="$PWD/data"
+          '';
+        };
+      });
+}