RateLimit

The RateLimit middleware ensures that services will receive a fair amount of requests, and allows one to define what fair is.

It is based on a token bucket implementation. In this analogy, the average parameter (defined below) is the rate at which the bucket refills, and the burst is the size (volume) of the bucket.

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Configuration Options

average

Field	Description
average	average is the maximum rate, by default in requests per second, allowed from a given source.

It defaults to 0, which means no rate limiting.

The rate is actually defined by dividing average by period.
For a rate below 1 req/s, one needs to define a period larger than a second.

Rate limit of 100 reqs/s

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    average: 100

period

Field	Description
period	period, in combination with average, defines the actual maximum rate.

Example:

r = average / period

It defaults to 1 second.

Rate limit of 6 reqs/minute

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    period: 1m
    average: 6

burst

Field	Description
burst	burst is the maximum number of requests allowed to go through in the same arbitrarily small period of time.

It defaults to 1.

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    burst: 100

sourceCriterion

Field	Description
sourceCriterion	The sourceCriterion option defines what criterion is used to group requests as originating from a common source.

If several strategies are defined at the same time, an error will be raised.
If none are set, the default is to use the request's remote address field (as an ipStrategy).

sourceCriterion.ipStrategy

Field	Description
sourceCriterion.ipStrategy	The ipStrategy option defines two parameters that configures how Traefik determines the client IP: depth, and excludedIPs.

info

As a middleware, rate-limiting happens before the actual proxying to the backend takes place.
In addition, the previous network hop only gets appended to X-Forwarded-For during the last stages of proxying, that is after it has already passed through rate-limiting.
Therefore, during rate-limiting, as the previous network hop is not yet present in X-Forwarded-For, it cannot be found and/or relied upon.

ipStrategy.depth

Field	Description
ipStrategy.depth	The depth option tells Traefik to use the X-Forwarded-For header and select the IP located at the depth position (starting from the right).

• If depth is greater than the total number of IPs in X-Forwarded-For, then the client IP is empty.
• depth is ignored if its value is less than or equal to 0.

Example of Depth & X-Forwarded-For

If depth is set to 2, and the request X-Forwarded-For header is "10.0.0.1,11.0.0.1,12.0.0.1,13.0.0.1" then the "real" client IP is "10.0.0.1" (at depth 4) but the IP used as the criterion is "12.0.0.1" (depth=2).

X-Forwarded-For	depth	clientIP
"10.0.0.1,11.0.0.1,12.0.0.1,13.0.0.1"	1	"13.0.0.1"
"10.0.0.1,11.0.0.1,12.0.0.1,13.0.0.1"	3	"11.0.0.1"
"10.0.0.1,11.0.0.1,12.0.0.1,13.0.0.1"	5	""

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      ipStrategy:
        depth: 2

ipStrategy.excludedIPs

info

Contrary to what the name might suggest, this option is not about excluding an IP from the rate limiter, and therefore cannot be used to deactivate rate limiting for some IPs.
If depth is specified, excludedIPs is ignored.

excludedIPs is meant to address two classes of somewhat distinct use-cases:

1. Distinguish IPs which are behind the same (set of) reverse-proxies so that each of them contributes, independently to the others, to its own rate-limit "bucket" (cf the leaky bucket analogy). In this case, excludedIPs should be set to match the list of X-Forwarded-For IPs that are to be excluded, in order to find the actual clientIP.

Each IP as a distinct source

X-Forwarded-For	excludedIPs	clientIP
"10.0.0.1,11.0.0.1,12.0.0.1"	"11.0.0.1,12.0.0.1"	"10.0.0.1"
"10.0.0.2,11.0.0.1,12.0.0.1"	"11.0.0.1,12.0.0.1"	"10.0.0.2"

2. Group together a set of IPs (also behind a common set of reverse-proxies) so that they are considered the same source, and all contribute to the same rate-limit bucket.

Group IPs together as same source

X-Forwarded-For	excludedIPs	clientIP
"10.0.0.1,11.0.0.1,12.0.0.1"	"12.0.0.1"	"11.0.0.1"
"10.0.0.2,11.0.0.1,12.0.0.1"	"12.0.0.1"	"11.0.0.1"
"10.0.0.3,11.0.0.1,12.0.0.1"	"12.0.0.1"	"11.0.0.1"

For completeness, below are additional examples to illustrate how the matching works.
For a given request the list of X-Forwarded-For IPs is checked from most recent to most distant against the excludedIPs pool, and the first IP that is not in the pool (if any) is returned.

Matching for clientIP

X-Forwarded-For	excludedIPs	clientIP
"10.0.0.1,11.0.0.1,13.0.0.1"	"11.0.0.1"	"13.0.0.1"
"10.0.0.1,11.0.0.1,13.0.0.1"	"15.0.0.1,16.0.0.1"	"13.0.0.1"
"10.0.0.1,11.0.0.1"	"10.0.0.1,11.0.0.1"	""

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      ipStrategy:
        excludedIPs:
        - 127.0.0.1/32
        - 192.168.1.7

sourceCriterion.requestHeaderName

Field	Description
sourceCriterion.requestHeaderName	Name of the header used to group incoming requests.

Kubernetes CR

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
  sourceCriterion:
      requestHeaderName: username

sourceCriterion.requestHost

Field	Description
sourceCriterion.requestHost	Whether to consider the request host as the source.

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      requestHost: true

Example

Allowing burst

# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 200 requests is allowed.
apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    average: 100
    burst: 200