Run migrations on the first web instance startup

manifest.yml

@@ -21,7 +21,7 @@ applications:
       - type: web
         instances: ((web_instances))
         memory: ((web_memory))
-        command: ./scripts/run_app_paas.sh gunicorn -c ./gunicorn_config.py application
+        command: ./scripts/migrate_and_run_web.sh
       - type: worker
         instances: ((worker_instances))
         memory: ((worker_memory))

scripts/migrate_and_run_web.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if [[ $CF_INSTANCE_INDEX -eq 0 ]]; then
+  flask db upgrade
+fi
+
+${HOME}/scripts/run_app_paas.sh gunicorn -c ${HOME}/gunicorn_config.py application