From 7de29bd26f5e514e95d5d261c08f3029337eecb3 Mon Sep 17 00:00:00 2001
From: Oliver Charles <ollie@ocharles.org.uk>
Date: Sun, 6 Apr 2014 11:56:43 +0100
Subject: [PATCH 1/2] Create the 'postgres' superuser

Old PostgreSQL installations were created using the 'root' database
user. In this case, we need to create a new 'postgres' account, as we
now assume that this is the superuser account.

Unfortunately, these machines will be left with a 'root' user as
well (which will have ownership of some databases). While PostgreSQL
does let you rename superuser accounts, you can only do that when you
are connected as a *different* database user. Thus we'd have to create a
special superuser account to do the renaming. As we default to using
ident authentication, we would have to create a system level user to do
this. This all feels rather complex, so I'm currently opting to keep the
'root' user on these old machines.
---
 nixos/modules/services/databases/postgresql.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/nixos/modules/services/databases/postgresql.nix b/nixos/modules/services/databases/postgresql.nix
index 33ee7244e3f4..08a9cdd9f5da 100644
--- a/nixos/modules/services/databases/postgresql.nix
+++ b/nixos/modules/services/databases/postgresql.nix
@@ -197,6 +197,7 @@ in
                 fi
                 rm -f ${cfg.dataDir}/*.conf
                 touch "${cfg.dataDir}/.first_startup"
+                touch "${cfg.dataDir}/postgresql-user-created"
             fi
 
             ln -sfn "${configFile}" "${cfg.dataDir}/postgresql.conf"
@@ -230,6 +231,11 @@ in
                 sleep 0.1
             done
 
+            if ! [ -e ${cfg.dataDir}/postgresql-user-created ]; then
+              createuser --superuser postgres
+              touch ${cfg.dataDir}/postgresql-user-created
+            fi
+
             if test -e "${cfg.dataDir}/.first_startup"; then
               ${optionalString (cfg.initialScript != null) ''
                 cat "${cfg.initialScript}" | su -s ${pkgs.stdenv.shell} postgres -c 'psql postgres'

From e2066841106a6b89093ab685368742efa4e3c2c1 Mon Sep 17 00:00:00 2001
From: Oliver Charles <ollie@ocharles.org.uk>
Date: Sun, 6 Apr 2014 12:00:02 +0100
Subject: [PATCH 2/2] Use PostgreSQL 9.3's `pg_isready` to wait for
 connectivity

The postgresql module has a postStart section that waits for a database
to accept connections before continuing. However, this assumes various
properties about the database - specifically the database user
and (implicitly) the database name. This means that for old
installations, this command fails because there is no 'postgres' user,
and the service never starts.

While 7deff39 does create the 'postgres' user, a better solution is to
use `pg_isready`, who's sole purpose is to check if the database is
accepting connections. This has no dependency on users, so should be
more robust.
---
 nixos/modules/services/databases/postgresql.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nixos/modules/services/databases/postgresql.nix b/nixos/modules/services/databases/postgresql.nix
index 08a9cdd9f5da..ed66c15e304d 100644
--- a/nixos/modules/services/databases/postgresql.nix
+++ b/nixos/modules/services/databases/postgresql.nix
@@ -226,7 +226,7 @@ in
         # Wait for PostgreSQL to be ready to accept connections.
         postStart =
           ''
-            while ! su -s ${pkgs.stdenv.shell} postgres -c 'psql postgres -c ""' 2> /dev/null; do
+            while ! ${pkgs.postgresql93}/bin/pg_isready > /dev/null; do
                 if ! kill -0 "$MAINPID"; then exit 1; fi
                 sleep 0.1
             done