Basic Request Rate Limiting

Security

Not all of your endpoints are equally resilient. If you want to limit the amount of requests to a less resilient endpoint no matter the user, you can do so with basic request rate limiting.

The QoTM service deployed from the Ambassador directory exposes the routes /qotm/limited/ and /qotm/open/. The /qotm/limited/ can only handle as much load as is defined by the REQUEST_LIMIT environment variable (defaults to 5), meaning that after 5 requests in a minute, the server will return a 500 error. The /qotm/open/ endpoint, however, can handle higher loads.

You can test this by running the ratelimit.sh script in "basic" mode which sends a request every second. After the fifth request you will see the server a 500 error.

To protect our QoTM app, we need to put a rate limit on the number of requests that are allowed to the /qotm/limited/ route.

  1. Install Ambassador Pro

    Ambassador Pro is a commercial version of Ambassador that includes integrated Single Sign-On, powerful rate limiting, custom filters, and more. Ambassador Pro also uses a certified version of Ambassador OSS that undergoes additional testing and validation.

    1. Clone the Ambassador Pro configuration repository

      Ambassador Pro consists of a series of modules that communicate with Ambassador. The core Pro module is typically deployed as a sidecar to Ambassador. This means it is an additional process that runs on the same pod as Ambassador. Ambassador communicates with the Pro sidecar locally. Pro thus scales in parallel with Ambassador. Ambassador Pro also relies on a Redis instance for its rate limit service and several Custom Resource Definitions (CRDs) for configuration.

      For this installation, we'll start with a standard set of Ambassador Pro configuration files.

      git clone https://github.com/datawire/pro-ref-arch
    2. License Key

      Copy env.sh.example to env.sh, and add your specific license key to the env.sh file. If you don’t have a license key, you can request a free 14-day trial key now.

      Note: Ambassador Pro will not start without a valid license key.

    3. Deploy Ambassador Pro

      If you're on GKE, first, create the following ClusterRoleBinding:

      kubectl create clusterrolebinding my-cluster-admin-binding \
      --clusterrole=cluster-admin \
      --user=$(gcloud info --format="value(config.account)")
      

      Then, deploy Ambassador Pro:

      make apply-ambassador

      This make command will use kubectl to deploy Ambassador Pro and a basic test configuration to the cluster.

      Verify that Ambassador Pro is running:

      kubectl get pods | grep ambassador
      ambassador-79494c799f-vj2dv            2/2       Running            0         1h
      ambassador-pro-redis-dff565f78-88bl2   1/1       Running            0         1h
      

      Note: If you are not deploying in a cloud environment that supports the LoadBalancertype, you will need to change the ambassador/ambassador-service.yaml to a different service type (e.g., NodePort).

      By default, Ambassador Pro uses ports 8081 and 8082 for rate-limiting and filtering, respectively. If for whatever reason those assignments are problematic (perhaps you set service_port to one of those), you can set adjust these by setting environment variables:

      • GRPC_PORT: Which port to serve the RateLimitService on; 8081 by default.
      • APRO_AUTH_PORT: Which port to serve the filtering AuthService on; 8082 by default.

      If you have deployed Ambassador with AMBASSADOR_NAMESPACE, AMBASSADOR_SINGLE_NAMESPACE, or AMBASSADOR_ID set, you will also need to set them in the Pro container.

  2. In the pro-ref-arch directory, observe the Mappings in ambassador/05-qotm.yaml we deployed earlier.

    You will see a labels applied to the qotm_limited_mapping. This configures Ambassador to label the request with the string qotm. We will configure Ambassador to RateLimit off this label.

      ---
      apiVersion: ambassador/v1
      kind: Mapping
      name: qotm_limited_mapping
      prefix: /qotm/limited/
      rewrite: /limited/
      service: qotm
      labels:
        ambassador:
          - string_request_label:
            - qotm

    Note: There is no label applied to the qotm_open_mapping.

  3. Configure the RateLimit:

    kubectl apply -f ratelimit/rl-basic.yaml

    We have now configured Ambassador to limit requests containing the label qotm to 5 requests per minute.

  4. Test the RateLimit:

    ratelimit/ratelimit-test.sh basic

    This is a simple bash script that sends a cURL to http://$AMBASSADOR_IP/qotm/limited/ every second. You will notice that after the 5th request, Ambassador is returning a 429 instead of 200 to requests to the /qotm/limited/ endpoint.

    The /qotm/open/ endpoint does not have the same load restrictions and therefore does not need to be rate limited.

Summary

To quickly enable basic request rate limiting on your website, get started with a free 14-day trial of Ambassador Pro, or contact sales today.