A basic sample application that demonstrates blue/green deployment with a share database:
1. Login to a scratch org and space
2. Deploy a database using the `dto-shared-pgsql` broker. This database must be called `blue-green-db` as this matches the name of the service in `manifest.yml`
`cf create-service dto-shared-pgsql shared-psql blue-green-db`
3. `cf push`
cf will push the `blue` app, then the `green` app.
TODO: currently you get two apps, `blue.domain` and `green.domain`, binding them to a single route is not working yet.