Supported running cleanup job on GCP (#719)

ref https://linear.app/ghost/issue/PROD-685

Connecting to CloudSQL isn't done in the usual way, we need to use the unix socket
which is mounted automatically for Cloud Run Jobs at /cloudsql/<instance-name>

Author: allouis

jobs/cleanup-expired-key-value-records/cleanup-expired-key-value-records

@@ -1,10 +1,17 @@
 #!/bin/sh
 set -e
 
-mysql \
-  --host="$MYSQL_HOST" \
-  --port="$MYSQL_PORT" \
-  --user="$MYSQL_USER" \
-  --password="$MYSQL_PASSWORD" \
-  --database="$MYSQL_DATABASE" \
-  -e "DELETE FROM key_value WHERE expires IS NOT NULL AND expires < UTC_TIMESTAMP();"
+PORT=${MYSQL_PORT:-3306}
+
+if [ -n "$MYSQL_SOCKET_PATH" ]; then
+  echo "Using Unix socket for $MYSQL_SOCKET_PATH"
+  SOCKET="--socket=$MYSQL_SOCKET_PATH"
+  HOSTPORT=""
+else
+  echo "Using TCP host $MYSQL_HOST:$PORT"
+  SOCKET=""
+  HOSTPORT="--host=$MYSQL_HOST --port=$PORT"
+fi
+
+mysql $SOCKET $HOSTPORT -u "$MYSQL_USER" -p"$MYSQL_PASSWORD" "$MYSQL_DATABASE" -e \
+  "DELETE FROM key_value WHERE expires IS NOT NULL AND expires < UTC_TIMESTAMP();"