Inject Custom Headers into Aeraki Mesh Using MetaRouter CRD

Installation of Example Programs

Install Aeraki, Istio, and the sample applications. After installation two namespaces, meta-dubbo and meta-thrift, appear, each containing a sample service for Dubbo or Thrift.

kubectl get ns | grep meta
meta-dubbo        Active   16m
meta-thrift       Active   16m

Modifying Request Message Header

Aeraki supports header mutation via a MetaRouter custom resource. The following manifest adds two headers ( foo: bar and foo1: bar1) to outgoing Thrift requests.

apiVersion: metaprotocol.aeraki.io/v1alpha1
kind: MetaRouter
metadata:
  name: test-metaprotocol-thrift-route
  namespace: meta-thrift
spec:
  hosts:
    - thrift-sample-server.meta-thrift.svc.cluster.local
  routes:
    - name: header-mutation
      route:
        - destination:
            host: thrift-sample-server.meta-thrift.svc.cluster.local
      requestMutation:
        - key: foo
          value: bar
        - key: foo1
          value: bar1

Apply the manifest: kubectl apply -f - Sidecar logs show the injected headers:

2022-03-10T06:42:25.605305Z	info	envoy filter	thrift: codec mutation foo : bar
2022-03-10T06:42:25.605316Z	info	envoy filter	thrift: codec mutation foo1 : bar1

Underlying Mechanism

Aeraki configures an outbound listener for the Thrift service and inserts the envoy.filters.network.meta_protocol_proxy filter. The filter points to Aeraki’s internal RDS server, which receives the translated routing rules from the MetaRouter resource.

Outbound listener configuration (JSON):

{
  "name": "envoy.filters.network.meta_protocol_proxy",
  "typed_config": {
    "@type": "type.googleapis.com/udpa.type.v1.TypedStruct",
    "type_url": "type.googleapis.com/aeraki.meta_protocol_proxy.v1alpha.MetaProtocolProxy",
    "value": {
      "stat_prefix": "outbound|9090||thrift-sample-server.meta-thrift.svc.cluster.local",
      "application_protocol": "thrift",
      "rds": {
        "config_source": {
          "api_config_source": {
            "api_type": "GRPC",
            "grpc_services": [
              {
                "envoy_grpc": {
                  "cluster_name": "aeraki-xds"
                }
              }
            ],
            "transport_api_version": "V3"
          },
          "resource_api_version": "V3"
        },
        "route_config_name": "thrift-sample-server.meta-thrift.svc.cluster.local_9090"
      },
      "codec": {
        "name": "aeraki.meta_protocol.codec.thrift"
      },
      "meta_protocol_filters": [
        {
          "name": "aeraki.meta_protocol.filters.router"
        }
      ]
    }
  }
}

The RDS dump confirms that the route named “header‑mutation” contains the request_mutation entries for the two headers:

{
  "@type": "type.googleapis.com/aeraki.meta_protocol_proxy.admin.v1alpha.RoutesConfigDump",
  "dynamic_route_configs": [
    {
      "version_info": "1641896797",
      "route_config": {
        "@type": "type.googleapis.com/aeraki.meta_protocol_proxy.config.route.v1alpha.RouteConfiguration",
        "name": "thrift-sample-server.meta-thrift.svc.cluster.local_9090",
        "routes": [
          {
            "name": "header-mutation",
            "route": {
              "cluster": "outbound|9090||thrift-sample-server.meta-thrift.svc.cluster.local"
            },
            "request_mutation": [
              { "key": "foo", "value": "bar" },
              { "key": "foo1", "value": "bar1" }
            ]
          }
        ]
      },
      "last_updated": "2022-03-10T06:26:24.083Z"
    }
  ],
  "last_updated": "2022-01-11T10:26:37.357Z"
}

To view the sidecar proxy configuration, run:

aerakictl_sidecar_config client meta-thrift | fx