templates: bump max postgres connections to 10

By default, pgxpool.Pool has 4 connections (or number of cpus if higher).
Currently, we have 3 replicas, that means max 3*4=12 DB connections.

The dequeue operation is actually blocking - when a worker is waiting for
a job, one connection is blocked. My theory is that with 16 workers, we just
don't have enough connections that causes all sorts of weird slowdowns.

This commit bumps the number of connection from one replica to 10, therefore
we should be at 30 connections in total.

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

templates/composer.yml

@@ -92,6 +92,8 @@ objects:
                 key: db.password
           - name: PGSSLMODE
             value: "${PGSSLMODE}"
+          - name: PGMAXCONNS
+            value: "${PGMAXCONNS}"
           ports:
           - name: composer-api
             protocol: TCP
@@ -229,6 +231,9 @@ parameters:
   - description: postgres sslmode to use when connecting to the db
     name: PGSSLMODE
     value: "require"
+  - description: postgres maximum connections per pod
+    name: PGMAXCONNS
+    value: "10"
   - description: base sso url
     name: SSO_BASE_URL
     required: true

test/cases/api.sh

@@ -79,6 +79,7 @@ pg_database = "osbuildcomposer"
 pg_user = "postgres"
 pg_password = "foobar"
 pg_ssl_mode = "disable"
+pg_max_conns = 10
 EOF
 
 sudo systemctl restart osbuild-composer