Provide more context when wating for PostgreSQL takes too long (#3782)

{{cookiecutter.project_slug}}/compose/production/django/entrypoint

@@ -16,13 +16,17 @@ if [ -z "${POSTGRES_USER}" ]; then
 fi
 export DATABASE_URL="postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}"
 
-postgres_ready() {
 python << END
 import sys
+import time
 
 import psycopg2
 
-try:
+suggest_unrecoverable_after = 30
+start = time.time()
+
+while True:
+    try:
         psycopg2.connect(
             dbname="${POSTGRES_DB}",
             user="${POSTGRES_USER}",
@@ -30,16 +34,16 @@ try:
             host="${POSTGRES_HOST}",
             port="${POSTGRES_PORT}",
         )
-except psycopg2.OperationalError:
+        break
-    sys.exit(-1)
+    except psycopg2.OperationalError as error:
-sys.exit(0)
+        sys.stderr.write("Waiting for PostgreSQL to become available...\n")
 
+        if time.time() - start > suggest_unrecoverable_after:
+            sys.stderr.write("  This is taking longer than expected. The following exception may be indicative of an unrecoverable error: '{}'\n".format(error))
+
+    time.sleep(1)
 END
-}
+
-until postgres_ready; do
-  >&2 echo 'Waiting for PostgreSQL to become available...'
-  sleep 1
-done
 >&2 echo 'PostgreSQL is available'
 
 exec "$@"