The env block consists of a heading, then one or more environment variable/value pairs.

For example:

---
  ...
  env:
    RAILS_ENV: production
    RACK_ENV: production

cf push deploys the application to a container on the server. The variables belong to the container environment.

While the application is running, Cloud Foundry allows you to operate on environment variables.

Environment variables interact with manifests in the following ways: