Define custom headers

Media CDN lets you specify custom request and response headers.

Custom headers let you do the following:

• Return geographic data about the client, such as country, region, or city, that you can use to show localized content.
• Determine whether a response was served from cache (in full or in part) and which cache location it was served from.
• Remove, replace, or append to both request and response headers.

Set custom headers

Headers are set on each route, which lets you add and remove headers for different content, such as manifests or video segments.

Set per-route custom request headers early in the CDN processing path, prior to caching decisions. For example, if you set a cache-control header as a per-route custom header, it affects caching behavior in the CDN.

By default, added header values are comma-separated and appended to the response or request headers with the same field names.

To overwrite existing values, set replace to true.

gcloud edge-cache services describe prod-media-service

routeRules:
- priority: 1
   description: "video routes"
   matchRules:
      - prefixMatch: "/video/"
   headerAction:
      responseHeadersToAdd:
      # Return the country (or region) associated with the client's IP address.
      - headerName: "client-geo"
         headerValue: "{client_region}"
         replace: true
      requestHeadersToAdd:
      # Inform the upstream origin server the request is from Media CDN
      - headerName: "x-downstream-cdn"
         headerValue: "Media CDN"
      responseHeadersToRemove:
      - headerName: "X-User-ID"
      - headerName: "X-Other-Internal-Header"

route_rule {
  description = "video routes"
  priority    = 1
  match_rule {
    prefix_match = "/video/"
  }
  origin = google_network_services_edge_cache_origin.default.name
  header_action {
    response_header_to_add {
      # Return the country (or region) associated with the client's IP address.
      header_name  = "client-geo"
      header_value = "{client_region}"
      replace      = true
    }
    request_header_to_add {
      # Inform the upstream origin server that the request is from Media CDN.
      header_name  = "x-downstream-cdn"
      header_value = "Media CDN"
    }
    response_header_to_remove {
      header_name = "X-User-ID"
    }
    response_header_to_remove {
      header_name = "X-Other-Internal-Header"
    }
  }
}

This example does the following:

• Adds a custom client-geo header to the response by using the {client_region} variable, which returns the country (or region) associated with the client's IP address.
• Adds a custom x-downstream-cdn header to the request by using a static string.
• Removes two internal headers.

To configure origin-specific custom headers, see Configure origin-specific host rewrites or header modifications.

Dynamic header variables

Custom headers can contain one or more dynamic variables.

Request headers that are a part of cache key policy (cacheKeyPolicy.includedHeaderNames) can contain one or more custom variables. Request headers that contain other dynamic variables can't be a part of the cache key.