Apply PGTune recommendations to PostgreSQL in prod

This is just using the recommendations from PGTune for a web application
being hosted on a server with the prod server's specs. I'm sure they're
not the best values, but should be better than the defaults.

salt/salt/postgresql/prod-config.sls

@@ -0,0 +1,25 @@
+# Values from PGTune (https://pgtune.leopard.in.ua/)
+{% set setting_values = {
+    "checkpoint_completion_target": "0.7",
+    "default_statistics_target": "100",
+    "effective_cache_size": "24GB",
+    "effective_io_concurrency": 200,
+    "maintenance_work_mem": "2GB",
+    "max_parallel_workers": "8",
+    "max_parallel_workers_per_gather": "4",
+    "max_wal_size": "2GB",
+    "max_worker_processes": "8",
+    "min_wal_size": "1GB",
+    "random_page_cost": "1.1",
+    "shared_buffers": "8GB",
+    "wal_buffers": "16MB",
+    "work_mem": "10485kB",
+} %}
+
+{% for setting, value in setting_values.items() %}
+postgresql-conf-set-{{ setting }}:
+  file.replace:
+    - name: /etc/postgresql/{{ pillar['postgresql_version'] }}/main/postgresql.conf
+    - pattern: '^#?{{ setting }} = (?!{{ value }}).*$'
+    - repl: '{{ setting }} = {{ value }}'
+{% endfor %}

salt/salt/top.sls

@@ -31,6 +31,7 @@ base:
   'prod':
     - nginx.shortener-config
     - nginx.static-sites-config
+    - postgresql.prod-config
     - prod-config
   'monitoring':
     - nginx