r/postgresql-server: Add script to upgrade database

The `postgresql-upgrade.sh` script arranges to run `pg_upgrade` after a
major PostgreSQL version update.  It's scheduled by a systemd unit,
_postgresql-upgrade.service_, which runs only after an OS update.

roles/postgresql-server/files/postgresql-upgrade.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Upgrade PostgreSQL database cluster
+Before=postgresql.service
+Before=systemd-update-done.service
+After=local-fs.target
+RequiresMountsFor=/var/lib/pgsql
+DefaultDependencies=no
+ConditionNeedsUpdate=/var
+
+[Service]
+Type=oneshot
+User=postgres
+ExecStart=+/usr/local/libexec/postgresql-upgrade
+Environment=PG_COLOR=always
+WorkingDirectory=~
+
+[Install]
+RequiredBy=postgresql.service

roles/postgresql-server/files/postgresql-upgrade.sh

@@ -0,0 +1,40 @@
+#!/bin/sh
+# vim: set sw=4 ts=4 sts=4 et :
+
+set -e
+
+CONFIG_DIR=/etc/postgresql
+
+data_directory=$(
+    runuser -u postgres -- postgres -D "${CONFIG_DIR}" -C data_directory
+)
+old_version=$(cat "${data_directory}"/PG_VERSION)
+current_version=$(postgres --version | sed -r 's/.*\s+([0-9]+).*/\1/')
+
+if [ "${old_version}" = "${current_version}" ]; then
+    exit 0
+fi
+
+config_dir_old="${CONFIG_DIR}.${old_version}"
+rm -rf "${config_dir_old}"
+cp -a "${CONFIG_DIR}" "${config_dir_old}"
+
+sed -ri.orig \
+    -e 's/data_directory\s*=\s*'\''(.*?)'\''/data_directory = '\''\1.'"${old_version}"\''/' \
+    -e 's/^(\s*ssl\s*=\s*)(.*)$/\1off/' \
+    "${config_dir_old}"/postgresql.conf
+sed -i.orig \
+    -e '$alocal all postgres peer' \
+    -e d \
+    "${config_dir_old}"/pg_hba.conf
+mv "${data_directory}" "${data_directory}.${old_version}"
+runuser -u postgres -- initdb -A peer --no-instructions "${data_directory}"
+
+runuser -u postgres -- pg_upgrade \
+    -b "/usr/lib64/pgsql/postgresql-${old_version}"/bin \
+    -B /usr/bin \
+    -d "${config_dir_old}" \
+    -D "${CONFIG_DIR}" \
+    -o '-c restore_command= -c archive_command=' \
+    -O '-c restore_command= -c archive_command=' \
+    -k

roles/postgresql-server/meta/main.yml

@@ -0,0 +1,2 @@
+dependencies:
+- systemd-base

roles/postgresql-server/tasks/main.yml

@@ -1,6 +1,8 @@
 - name: ensure postgresql-server is installed
   package:
-    name: postgresql-server
+    name:
+    - postgresql-server
+    - postgresql-upgrade
     state: present
   tags:
   - install
@@ -130,6 +132,35 @@
   tags:
   - systemd
 
+- name: ensure postgresql-upgrade script is installed
+  copy:
+    src: postgresql-upgrade.sh
+    dest: /usr/local/libexec/postgresql-upgrade
+    owner: root
+    group: root
+    mode: u=rwx,go=rx
+  tags:
+  - postgresql-upgrade
+- name: ensure postgresql-upgrade systemd unit is installed
+  copy:
+    src: postgresql-upgrade.service
+    dest: /etc/systemd/system/postgresql-upgrade.service
+    owner: root
+    group: root
+    mode: u=rw,go=r
+  notify:
+  - reload systemd
+  tags:
+  - postgresql-upgrade
+  - systemd
+
+- name: ensure postgresql-upgrade service starts when needed
+  service:
+    name: postgresql-upgrade
+    enabled: true
+  tags:
+  - postgresql-upgrade
+  - service
 - name: ensure postgresql starts at boot
   service:
     name: postgresql