traefik-cluster-ratelimit

Traefik comes with a default rate limiter middleware, but the rate limiter doesn't share a state if you are using several instance of Traefik (think kubernetes HA deployment for example).

This plugin is here to solve this issue: using a Redis as a common state, this plugin implement the token bucket algorithm.

Configuration

You need to setup the static and dynamic configuration

The following declaration (given here in YAML) defines the plugin:

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# Static configuration

experimental:
  plugins:
    clusterRatelimit:
      moduleName: "github.com/nzin/traefik-cluster-ratelimit"
      version: "v1.1.1"

Here is an example of a file provider dynamic configuration (given here in YAML), where the interesting part is the http.middlewares section:

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# Dynamic configuration

http:
  routers:
    my-router:
      rule: host(`demo.localhost`)
      service: service-foo
      entryPoints:
        - web
      middlewares:
        - my-middleware

  services:
   service-foo:
      loadBalancer:
        servers:
          - url: http://127.0.0.1:5000
  
  middlewares:
    my-middleware:
      plugin:
        clusterRatelimit:
          average: 50
          burst: 100

With a kubernetesingress provider:

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apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: clusterratelimit
  namespace: ingress-traefik
spec:
  clusterRatelimit:
    average: 100
    burst: 200
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
  namespace: ingress-traefik
  annotations:
    traefik.ingress.kubernetes.io/router.middlewares: ingress-traefik-clusterratelimit@kubernetescrd
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: example-service
            port:
              number: 80

Extra configuration

The average and the burst are the number of allowed connection per second, there are other variables:

Variable	Description	default
period	the period (in seconds) of the rate limiter window	1
average	allowed requests per "period" ( 0 = unlimited)
burst	allowed burst requests per "period"
redisAddress	address of the redis server	redis:6379
redisDb	redis db to use	0
redisPassword	redis authentication (if any)
sourceCriterion.*	defines what criterion is used to group requests. See next	ipStrategy
sourceCriterion.ipStrategy	client IP based source
sourceCriterion.ipStrategy.depth	tells Traefik to use the X-Forwarded-For header and select the IP located at the depth position
sourceCriterion.ipStrategy.excludedIPs	list of X-Forwarded-For IPs that are to be excluded
sourceCriterion.requestHost	based source on request host
sourceCriterion.requestHeaderName	Name of the header used to group incoming requests
breakerThreshold	number of failed connection before pausing Redis	3
breakerReattempt	nb seconds before attempting to reconnect to Redis	15
redisConnectionTimeout	redis connection timeout (in seconds)	2

Notes:

• for more information about sourceCriteron check the Traefik ratelimit page
• regarding redispassword, if you dont want to set it in clear text in the traefik configuration, you can specify a variable name starting with '$'. For example $REDIS_PASSWORD will use the REDIS_PASSWORD environment variable

A full example would be

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# Dynamic configuration

http:
  ...
  middlewares:
    my-middleware:
      plugin:
        clusterRatelimit:
          average: 5
          burst: 10
          period: 10
          sourceCriterion:
            ipStrategy:
              depth: 2
              excludedIPs:
              - 127.0.0.1/32
              - 192.168.1.7          
          redisAddress: redis:6379
          redisPassword: $REDIS_AUTH_PASSWORD
          redisConnectionTimeout: 2

Circuit-breaker

If the Redis server is not available, we will stop talking to it, and let pass through. As mentionned above there are 2 variables you can use to change the default behaviour: breakerThreshold and breakerReattempt. Usually you dont need to tweak that.

Benchmark

You can test traefik with the rate limiter with some tools. For example with vegeta (you probably need to install it):

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docker-compose up -d

echo "GET http://localhost:8000/" | vegeta attack -duration=5s -rate=200 | tee results.bin | vegeta report