Portable database health check (#70)

* Portable database health check

to ensure that the Django migrations do not run until the database is
fully up.

The previous solution, to use the long form of `depends_on:` in our
compose.yaml file, isn't supported by podman-compose:
containers/podman-compose#453

* Switch to using a bash heredoc

to more readably construct the Python script to be run.

Author: jbradberry

tools/docker-compose/compose.yaml

@@ -6,10 +6,8 @@ services:
       context: $PWD
       dockerfile: wisdom-service.Containerfile
     depends_on:
-      redis:
-        condition: service_started
-      db:
-        condition: service_healthy
+      - redis
+      - db
     restart: always
     volumes:
       - $PWD/ansible_wisdom:/var/www/ansible_wisdom
@@ -43,8 +41,6 @@ services:
       - POSTGRES_DB=wisdom
       - POSTGRES_USER=wisdom
     restart: always
-    healthcheck:
-      test: pg_isready -U wisdom
     networks:
       - dbnet
 # Disabled because this doesn't work properly on MacOS.

tools/scripts/launch-wisdom.sh

@@ -1,4 +1,24 @@
 #!/bin/bash
+set -o errexit
+
+database_ready() {
+/var/www/venv/bin/python ansible_wisdom/manage.py shell <<EOF
+import sys
+from django.db import connection
+
+try:
+    connection.ensure_connection()
+except Exception:
+    sys.exit(1)
+EOF
+}
+
+until database_ready
+do
+    echo "Waiting until the database is ready..."
+    sleep 5
+done
+
 /var/www/venv/bin/python ansible_wisdom/manage.py migrate --noinput
 
 cd ansible_wisdom/