Copy Postgres data across to a fresh DB when migrating on Heroku

This works around #183 by avoiding reuse of the old Ruby app.

Note that we don't copy over the Redis data; this is only used to sync
websockets and considered ephemeral.

Author: textbook

deployment/README.md

@@ -91,6 +91,8 @@ So you're ready to set Postfacto up, choose a name for your app. We'll refer to
 
 ### Migrating a deployment
 
+ > ⚠️ **Warning**: the Heroku migration will attempt to migrate your data to a new database instance and delete the old one. Take a look at what the script is doing and make sure you understand the implications before running it.
+
 1. If you'd previously deployed a version of Postfacto prior to 4.0, run the migration script from the `heroku` directory:
     ```bash
     ./migrate.sh <web-app-name> <api-app-name>

deployment/migrate-heroku.sh

@@ -45,7 +45,11 @@ SESSION_TIME=${SESSION_TIME:-'""'}
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 "$SCRIPT_DIR/mixpanel.sh" "Heroku $(basename "${BASH_SOURCE[0]}")" "$@"
 
-ENABLE_ANALYTICS=false "$SCRIPT_DIR/upgrade.sh" ${API_HOST}
+heroku addons:create heroku-postgresql:hobby-dev -a ${WEB_HOST}
+heroku pg:copy DATABASE ${WEB_HOST}::DATABASE -a ${API_HOST} --confirm ${API_HOST}
+heroku addons:create heroku-redis:hobby-dev -a ${WEB_HOST}
+heroku config:set WEBSOCKET_PORT=4443 SESSION_TIME=${SESSION_TIME} -a ${WEB_HOST}
 
-heroku apps:delete -a ${WEB_HOST} -c ${WEB_HOST}
-heroku apps:rename -a ${API_HOST} ${WEB_HOST}
+ENABLE_ANALYTICS=false "$SCRIPT_DIR/upgrade.sh" ${WEB_HOST}
+
+heroku apps:delete -a ${API_HOST} -c ${API_HOST}