Best practices for REST API that access multiple environments - rest

Question

When writing a RESTful API that needs to access different environments such as a lab/test database and a production database, what's the best practices around setting up the API?
Should there be a #PathParam?:
/employee/{emp_id}/{environment}
/{environment}/employee/{emp_id}/
Should there be a #QueryParam?:
/employee/{emp_id}/?environment="test"
/employee/{emp_id}/?environment="prod"
Should there be a field in the payload?:
{"emp_id":"123","environment":"test"}
{"emp_id":"123","environment":"production"}

Answer 1

In fact I see two ways to handle this. The reason to use one or the other corresponds to what is the most convenient to implement in your RESTful application.
Using a path parameter
With this approach, it should be a path parameter at the very beginning of the resource path. So URL would be like this: /{environment}/employee/{emp_id}. Such approach is convenient if you have several applications deployed under different root paths. For example:
/test: application packaged with the configuration for the test environment
/prod: application packaged with the configuration for the production
In this case, applications for each environment are isolated.
Using a custom header
You could also a custom header to specify on which environment to route. Github uses something like that to select the version of the API to use. See this link: https://developer.github.com/v3/#current-version. It's not exactly the same thing but you could have something like that:
GET /employee/{emp_id}
x-env: test
A reverse proxy could handle this header and route the request to the right environment.
I'm not convinced by the approach within the payload since an field environment isn't actually a part of the representation for element resource employee. Regarding the query parameter approach, it's similar since such parameters apply to the request on the resource.
Hope it helps you,