From 1bb1c981b04f8e65f604cfbd43c3fc684b057235 Mon Sep 17 00:00:00 2001
From: Greg Hellings <greg.hellings@gmail.com>
Date: Tue, 9 Apr 2024 16:27:27 -0500
Subject: [PATCH] Add Postgres upgrade script

---
 hosts/myself/matrix.nix         |  2 ++
 modules/nixos/db.nix            |  1 +
 overlays/default.nix            |  1 +
 overlays/upgrade-pg-cluster.nix | 24 ++++++++++++++++++++++++
 4 files changed, 28 insertions(+)
 create mode 100644 overlays/upgrade-pg-cluster.nix

diff --git a/hosts/myself/matrix.nix b/hosts/myself/matrix.nix
index bc0b4c5..8dc250d 100644
--- a/hosts/myself/matrix.nix
+++ b/hosts/myself/matrix.nix
@@ -5,6 +5,8 @@ let
 	conn = "postgresql:///dendrite?sslmode=disable&host=/run/postgresql";
 in
 {
+	environment.systemPackages = with pkgs; [ upgrade-pg-cluster ];
+
 	greg.containers.matrix = {
 		tailscale = true;
 		subnet = "204";
diff --git a/modules/nixos/db.nix b/modules/nixos/db.nix
index 60c4d56..ec551d1 100644
--- a/modules/nixos/db.nix
+++ b/modules/nixos/db.nix
@@ -18,6 +18,7 @@ in {
 		services = {
 			postgresql = {
 				enable = true;
+				package = pkgs.postgresql_15;
 				checkConfig = true;
 				ensureDatabases = dbs;
 				ensureUsers = map (db: { name = db; ensureDBOwnership = true; }) dbs;
diff --git a/overlays/default.nix b/overlays/default.nix
index 0a660f9..648d8cf 100644
--- a/overlays/default.nix
+++ b/overlays/default.nix
@@ -60,6 +60,7 @@ in rec {
 	setup-ssh = prev.callPackage ./setup-ssh {
 		pkgs = final.pkgs;
 	};
+	upgrade-pg-cluster = prev.callPackage ./upgrade-pg-cluster.nix {};
 
 	# Overrides of packages
 	brew = prev.callPackage ./homebrew.nix {};
diff --git a/overlays/upgrade-pg-cluster.nix b/overlays/upgrade-pg-cluster.nix
new file mode 100644
index 0000000..a22e36e
--- /dev/null
+++ b/overlays/upgrade-pg-cluster.nix
@@ -0,0 +1,24 @@
+{ postgresql_15, postgresql_14, writeScriptBin, ... }:
+
+let
+	newPostgres = postgresql_15;
+	oldPostgres = postgresql_14;
+in writeScriptBin "upgrade-pg-cluster" ''
+	set -eux
+	systemctl stop postgresql
+
+	export NEWDATA="/var/lib/postgresql/${newPostgres.psqlSchema}"
+	export NEWBIN="${newPostgres}/bin"
+
+	export OLDDATA="/var/lib/postgresql/${oldPostgres.psqlSchema}"
+	export OLDBIN="${oldPostgres}/bin"
+
+	install -d -m 0700 -o postgres -g postgres "$NEWDATA"
+	cd "$NEWDATA"
+	sudo -u postgres "$NEWBIN/initdb" -D "$NEWDATA"
+
+	sudo -u postgres "$NEWBIN/pg_upgrade" \
+	    --old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \
+	    --old-bindir "$OLDBIN" --new-bindir "$NEWBIN" \
+	    "$@"
+''