OPA input format for Http API requests

[gituserjava]

In a use-case where OPA is being used as authorization provider from Envoy, what is the format with which OPA receives input from Envoy?

From postman I am calling my endpoint by passing the header x-custom-header: foo. It is first routed to envoy sidecar which in turn calls OPA and forwards the request headers to OPA. What is the format/pattern in which OPA receives the Http request? Please advise.

Request example:

GET /api/v1/employees/departments
Accept: */*
x-custom-header : foo

[srenatus]

In a use-case where OPA is being used as authorization provider from Envoy, what is the format with which OPA receives input from Envoy?

The input format depends on the configured transport_api_version in Envoy 👇

          http_filters:
          - name: envoy.ext_authz
            typed_config:
              '@type': type.googleapis.com/envoy.extensions.filters.http.ext_authz.v3.ExtAuthz
              transport_api_version: V3

📚 See the documentation of the Input Document

For multiple headers, Envoy will include them in the AttributeContext separated by commas (source):

    // The HTTP request headers. If multiple headers share the same key, they
    // must be merged according to the HTTP spec. All header keys must be
    // lower-cased, because HTTP header keys are case-insensitive.

(I've included that because of the extra info from the issue you've filed here: open-policy-agent/opa#3985)

[gituserjava]

@srenatus, thank you for the response. This helped in understanding the format.