EB Deploy to multiple environments

You can make the eb cli refer to different environments from different branches by adding config like the following to your .elasticbeanstalk/config.yml file:

branch-defaults:
  main:
    environment: staging
  production:
    environment: production

In this example When you run eb deploy from the "main" branch, it will deploy to your environment named "staging", whereas when you run it from the "production" branch, it will deploy to your environment named "production".

This approach requires each environment have a dedicated branch. To push one branch to multiple environments, you can use @adnan's answer and specify a branch when you use the eb deploy command:

eb deploy <environment_name>

To answer my own question. The AWS EB CLI 3+ has a nice interface to deploy to multiple environments. If you add another environment to your application you can simply deploy by using

eb deploy <environment-name>