Header-based routing

Emissary can route to target services based on HTTP headers with the headers and regex_headers specifications. Multiple mappings with different annotations can be applied to construct more complex routing rules.

The headers annotation

The headers attribute is a dictionary of header: value pairs. Emissary will only allow requests that match the specified header: value pairs to reach the target service.

Example

---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-backend
spec:
  prefix: /backend/
  service: quote
  headers:
    x-quote-mode: backend
    x-random-header: datawire

will allow requests to /backend/ to succeed only if the x-quote-mode header has the value backend and the x-random-header has the value datawire.

Regex headers

You can also set the value of a regex header to ".*" to test for the existence of a header.

Conditional example

---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-mode
spec:
  prefix: /backend/
  service: quote-mode
  regex_headers:
    x-quote-mode: ".*"

---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-regular
spec:
  prefix: /backend/
  service: quote-regular

will send requests that contain the x-quote-mode header to the quote-mode target, while routing all other requests to the quote-regular target.

The following mapping will route mobile requests from Android and iPhones to a mobile service:

---
apiVersion: getambassador.io/v3alpha1
kind:  Mapping
metadata:
  name:  quote-backend
spec:
  regex_headers:
    user-agent: ".*(iPhone|(a|A)ndroid).*"
  prefix: /backend/
  service: quote