Enabling Rate Limits using Envoy

 7 minute read     page test

This task shows you how to use Envoy’s native rate limiting to dynamically limit the traffic to an Istio service. In this task, you will apply a global rate-limit for the productpage service through ingress gateway that allows 1 requests per minute across all instances of the service. Additionally, you will apply a local rate-limit for each individual productpage instance that will allow 4 requests per minute. In this way, you will ensure that the productpage service handles a maximum of 1 request per minute through the ingress gateway, but each productpage instance can handle up to 4 requests per minute, allowing for any in-mesh traffic.

Before you begin

  1. Setup Istio in a Kubernetes cluster by following the instructions in the Installation Guide.

  2. Deploy the Bookinfo sample application.

Rate limits

Envoy supports two kinds of rate limiting: global and local. Global rate limiting uses a global gRPC rate limiting service to provide rate limiting for the entire mesh. Local rate limiting is used to limit the rate of requests per service instance. Local rate limiting can be used in conjunction with global rate limiting to reduce load on the global rate limiting service.

In this task you will configure Envoy to rate limit traffic to a specific path of a service using both global and local rate limits.

Global rate limit

Envoy can be used to set up global rate limits for your mesh. Global rate limiting in Envoy uses a gRPC API for requesting quota from a rate limiting service. A reference implementation of the API, written in Go with a Redis backend, is used below.

  1. Use the following configmap to configure the reference implementation to rate limit requests to the path /productpage at 1 req/min, a value api for the coming advanced example, and all other requests at 100 req/min.

    $ kubectl apply -f - <<EOF apiVersion: v1 kind: ConfigMap metadata: name: ratelimit-config data: config.yaml: | domain: ratelimit descriptors: - key: PATH value: "/productpage" rate_limit: unit: minute requests_per_unit: 1 - key: PATH value: "api" rate_limit: unit: minute requests_per_unit: 2 - key: PATH rate_limit: unit: minute requests_per_unit: 100 EOF

  2. Create a global rate limit service which implements Envoy’s rate limit service protocol. As a reference, a demo configuration can be found here, which is based on a reference implementation provided by Envoy.

    Zip
    $ kubectl apply -f @samples/ratelimit/rate-limit-service.yaml@

  3. Apply an EnvoyFilter to the ingressgateway to enable global rate limiting using Envoy’s global rate limit filter.

    The patch inserts the envoy.filters.http.ratelimit global envoy filter into the HTTP_FILTER chain. The rate_limit_service field specifies the external rate limit service, outbound|8081||ratelimit.default.svc.cluster.local in this case.

    $ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: EnvoyFilter metadata: name: filter-ratelimit namespace: istio-system spec: workloadSelector: # select by label in the same namespace labels: istio: ingressgateway configPatches: # The Envoy config you want to modify - applyTo: HTTP_FILTER match: context: GATEWAY listener: filterChain: filter: name: "envoy.filters.network.http_connection_manager" subFilter: name: "envoy.filters.http.router" patch: operation: INSERT_BEFORE # Adds the Envoy Rate Limit Filter in HTTP filter chain. value: name: envoy.filters.http.ratelimit typed_config: "@type": type.googleapis.com/envoy.extensions.filters.http.ratelimit.v3.RateLimit # domain can be anything! Match it to the ratelimter service config domain: ratelimit failure_mode_deny: true timeout: 10s rate_limit_service: grpc_service: envoy_grpc: cluster_name: outbound|8081||ratelimit.default.svc.cluster.local authority: ratelimit.default.svc.cluster.local transport_api_version: V3 EOF

  4. Apply another EnvoyFilter to the ingressgateway that defines the route configuration on which to rate limit. This adds rate limit actions for any route from a virtual host named bookinfo.com:80.

    $ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: EnvoyFilter metadata: name: filter-ratelimit-svc namespace: istio-system spec: workloadSelector: labels: istio: ingressgateway configPatches: - applyTo: VIRTUAL_HOST match: context: GATEWAY routeConfiguration: vhost: name: "" route: action: ANY patch: operation: MERGE # Applies the rate limit rules. value: rate_limits: - actions: # any actions in here - request_headers: header_name: ":path" descriptor_key: "PATH" EOF

Global rate limit advanced case

This example uses regex to match /api/* uri and defines a rate limit action inserted at the route level using the VirtualService http name. The PATH value api inserted in the prior example comes into play.

  1. Change VirtualService so the prefix /api/v1/products is moved to a route called api:

    $ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: bookinfo spec: gateways: - bookinfo-gateway hosts: - '*' http: - match: - uri: exact: /productpage - uri: prefix: /static - uri: exact: /login - uri: exact: /logout route: - destination: host: productpage port: number: 9080 - match: - uri: prefix: /api/v1/products route: - destination: host: productpage port: number: 9080 name: api EOF

  2. Apply an EnvoyFilter to add the rate limits action at the route level on any 1 to 99 product:

    $ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: EnvoyFilter metadata: name: filter-ratelimit-svc-api namespace: istio-system spec: workloadSelector: labels: istio: ingressgateway configPatches: - applyTo: HTTP_ROUTE match: context: GATEWAY routeConfiguration: vhost: name: "*:8080" route: name: "api" patch: operation: MERGE value: route: rate_limits: - actions: - header_value_match: descriptor_key: "PATH" descriptor_value: "api" headers: - name: ":path" safe_regex_match: google_re2: {} regex: "/api/v1/products/[1-9]{1,2}" EOF

Local rate limit

Envoy supports local rate limiting of L4 connections and HTTP requests. This allows you to apply rate limits at the instance level, in the proxy itself, without calling any other service.

The following EnvoyFilter enables local rate limiting for any traffic through the productpage service. The HTTP_FILTER patch inserts the envoy.filters.http.local_ratelimit local envoy filter into the HTTP connection manager filter chain. The local rate limit filter’s token bucket is configured to allow 4 requests/min. The filter is also configured to add an x-local-rate-limit response header to requests that are blocked.

$ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: EnvoyFilter metadata: name: filter-local-ratelimit-svc namespace: istio-system spec: workloadSelector: labels: app: productpage configPatches: - applyTo: HTTP_FILTER match: context: SIDECAR_INBOUND listener: filterChain: filter: name: "envoy.filters.network.http_connection_manager" patch: operation: INSERT_BEFORE value: name: envoy.filters.http.local_ratelimit typed_config: "@type": type.googleapis.com/udpa.type.v1.TypedStruct type_url: type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit value: stat_prefix: http_local_rate_limiter token_bucket: max_tokens: 4 tokens_per_fill: 4 fill_interval: 60s filter_enabled: runtime_key: local_rate_limit_enabled default_value: numerator: 100 denominator: HUNDRED filter_enforced: runtime_key: local_rate_limit_enforced default_value: numerator: 100 denominator: HUNDRED response_headers_to_add: - append: false header: key: x-local-rate-limit value: 'true' EOF

The above configuration applies local rate limiting to all vhosts/routes. Alternatively, you can restrict it to a specific route.

The following EnvoyFilter enables local rate limiting for any traffic to port 9080 of the productpage service. Unlike the previous configuration, there is no token_bucket included in the HTTP_FILTER patch. The token_bucket is instead defined in the second (HTTP_ROUTE) patch which includes a typed_per_filter_config for the envoy.filters.http.local_ratelimit local envoy filter, for routes to virtual host inbound|http|9080.

$ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: EnvoyFilter metadata: name: filter-local-ratelimit-svc namespace: istio-system spec: workloadSelector: labels: app: productpage configPatches: - applyTo: HTTP_FILTER match: context: SIDECAR_INBOUND listener: filterChain: filter: name: "envoy.filters.network.http_connection_manager" patch: operation: INSERT_BEFORE value: name: envoy.filters.http.local_ratelimit typed_config: "@type": type.googleapis.com/udpa.type.v1.TypedStruct type_url: type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit value: stat_prefix: http_local_rate_limiter - applyTo: HTTP_ROUTE match: context: SIDECAR_INBOUND routeConfiguration: vhost: name: "inbound|http|9080" route: action: ANY patch: operation: MERGE value: typed_per_filter_config: envoy.filters.http.local_ratelimit: "@type": type.googleapis.com/udpa.type.v1.TypedStruct type_url: type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit value: stat_prefix: http_local_rate_limiter token_bucket: max_tokens: 4 tokens_per_fill: 4 fill_interval: 60s filter_enabled: runtime_key: local_rate_limit_enabled default_value: numerator: 100 denominator: HUNDRED filter_enforced: runtime_key: local_rate_limit_enforced default_value: numerator: 100 denominator: HUNDRED response_headers_to_add: - append: false header: key: x-local-rate-limit value: 'true' EOF

Verify the results

Verify global rate limit

Send traffic to the Bookinfo sample. Visit http://$GATEWAY_URL/productpage in your web browser or issue the following command:

$ for i in {1..2}; do curl -s "http://$GATEWAY_URL/productpage" -o /dev/null -w "%{http_code}\n"; sleep 3; done 200 429 
$ for i in {1..3}; do curl -s "http://$GATEWAY_URL/api/v1/products/${i}" -o /dev/null -w "%{http_code}\n"; sleep 3; done 200 200 429

For /productpage, you will see the first request go through but every following request within a minute will get a 429 response. And for /api/v1/products/* you will need to hit twice, with any number in between 1-99, until you get the 429 response within a minute.

Verify local rate limit

Although the global rate limit at the ingress gateway limits requests to the productpage service at 1 req/min, the local rate limit for productpage instances allows 4 req/min. To confirm this, send internal productpage requests, from the ratings pod, using the following curl command:

$ kubectl exec "$(kubectl get pod -l app=ratings -o jsonpath='{.items[0].metadata.name}')" -c ratings -- bash -c 'for i in {1..5}; do curl -s productpage:9080/productpage -o /dev/null -w "%{http_code}\n"; sleep 1; done' 200 200 200 200 429

You should see no more than 4 req/min go through per productpage instance.

Cleanup

Zip
$ kubectl delete envoyfilter filter-ratelimit -nistio-system $ kubectl delete envoyfilter filter-ratelimit-svc -nistio-system $ kubectl delete envoyfilter filter-ratelimit-svc-api -nistio-system $ kubectl delete envoyfilter filter-local-ratelimit-svc -nistio-system $ kubectl delete cm ratelimit-config $ kubectl delete -f @samples/ratelimit/rate-limit-service.yaml@
Was this information useful?
Do you have any suggestions for improvement?

Thanks for your feedback!