# RateLimit

To Control the Number of Requests Going to a Service
{: .subtitle }

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

## Configuration Example

```yaml tab="Docker"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
  - "traefik.http.middlewares.test-ratelimit.ratelimit.burst=50"
```

```yaml tab="Kubernetes"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    average: 100
    burst: 50
```

```yaml tab="Consul Catalog"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
- "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
- "traefik.http.middlewares.test-ratelimit.ratelimit.burst=50"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.average": "100",
  "traefik.http.middlewares.test-ratelimit.ratelimit.burst": "50"
}
```

```yaml tab="Rancher"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
  - "traefik.http.middlewares.test-ratelimit.ratelimit.burst=50"
```

```yaml tab="File (YAML)"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        average: 100
        burst: 50
```

```toml tab="File (TOML)"
# Here, an average of 100 requests per second is allowed.
# In addition, a burst of 50 requests is allowed.
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    average = 100
    burst = 50
```

## Configuration Options

### `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`.
So for a rate below 1 req/s, one needs to define a `period` larger than a second.

```yaml tab="Docker"
# 100 reqs/s
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
```

```yaml tab="Kubernetes"
# 100 reqs/s
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    average: 100
```

```yaml tab="Consul Catalog"
# 100 reqs/s
- "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.average": "100",
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=100"
```

```yaml tab="File (YAML)"
# 100 reqs/s
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        average: 100
```

```toml tab="File (TOML)"
# 100 reqs/s
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    average = 100
```

### `period`

`period`, in combination with `average`, defines the actual maximum rate, such as:

```go
r = average / period
```

It defaults to `1` second.

```yaml tab="Docker"
# 6 reqs/minute
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=6"
  - "traefik.http.middlewares.test-ratelimit.ratelimit.period=1m"
```

```yaml tab="Kubernetes"
# 6 reqs/minute
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    period: 1m
    average: 6
```

```yaml tab="Consul Catalog"
# 6 reqs/minute
- "traefik.http.middlewares.test-ratelimit.ratelimit.average=6"
- "traefik.http.middlewares.test-ratelimit.ratelimit.period=1m"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.average": "6",
  "traefik.http.middlewares.test-ratelimit.ratelimit.period": "1m",
}
```

```yaml tab="Rancher"
# 6 reqs/minute
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.average=6"
  - "traefik.http.middlewares.test-ratelimit.ratelimit.period=1m"
```

```yaml tab="File (YAML)"
# 6 reqs/minute
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        average: 6
        period: 1m
```

```toml tab="File (TOML)"
# 6 reqs/minute
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    average = 6
    period = "1m"
```

### `burst`

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

It defaults to `1`.

```yaml tab="Docker"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.burst=100"
```

```yaml tab="Kubernetes"
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    burst: 100
```

```yaml tab="Consul Catalog"
- "traefik.http.middlewares.test-ratelimit.ratelimit.burst=100"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.burst": "100",
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.burst=100"
```

```yaml tab="File (YAML)"
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        burst: 100
```

```toml tab="File (TOML)"
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    burst = 100
```

### `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`

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

##### `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 "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`     | `""`         |

```yaml tab="Docker"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.depth=2"
```

```yaml tab="Kubernetes"
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      ipStrategy:
        depth: 2
```

```yaml tab="Consul Catalog"
- "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.depth=2"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.depth": "2"
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.depth=2"
```

```yaml tab="File (YAML)"
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        sourceCriterion:
          ipStrategy:
            depth: 2
```

```toml tab="File (TOML)"
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    [http.middlewares.test-ratelimit.rateLimit.sourceCriterion.ipStrategy]
      depth = 2
```

##### `ipStrategy.excludedIPs`

!!! important "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."

!!! important "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](https://wikipedia.org/wiki/Leaky_bucket)).
   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.

    !!! example "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.

    !!! example "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.

!!! example "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"` | `""`         |

```yaml tab="Docker"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.excludedips=127.0.0.1/32, 192.168.1.7"
```

```yaml tab="Kubernetes"
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      ipStrategy:
        excludedIPs:
        - 127.0.0.1/32
        - 192.168.1.7
```

```yaml tab="Consul Catalog"
- "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.excludedips=127.0.0.1/32, 192.168.1.7"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.excludedips": "127.0.0.1/32, 192.168.1.7"
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.ipstrategy.excludedips=127.0.0.1/32, 192.168.1.7"
```

```yaml tab="File (YAML)"
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        sourceCriterion:
          ipStrategy:
            excludedIPs:
              - "127.0.0.1/32"
              - "192.168.1.7"
```

```toml tab="File (TOML)"
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    [http.middlewares.test-ratelimit.rateLimit.sourceCriterion.ipStrategy]
      excludedIPs = ["127.0.0.1/32", "192.168.1.7"]
```

#### `sourceCriterion.requestHeaderName`

Name of the header used to group incoming requests.

```yaml tab="Docker"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requestheadername=username"
```

```yaml tab="Kubernetes"
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
	sourceCriterion:
      requestHeaderName: username
```

```yaml tab="Consul Catalog"
- "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requestheadername=username"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requestheadername": "username"
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requestheadername=username"
```

```yaml tab="File (YAML)"
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        sourceCriterion:
          requestHeaderName: username
```

```toml tab="File (TOML)"
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    [http.middlewares.test-ratelimit.rateLimit.sourceCriterion]
      requestHeaderName = "username"
```

#### `sourceCriterion.requestHost`

Whether to consider the request host as the source.

```yaml tab="Docker"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requesthost=true"
```

```yaml tab="Kubernetes"
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: test-ratelimit
spec:
  rateLimit:
    sourceCriterion:
      requestHost: true
```

```yaml tab="Consul Catalog"
- "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requesthost=true"
```

```json tab="Marathon"
"labels": {
  "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requesthost": "true"
}
```

```yaml tab="Rancher"
labels:
  - "traefik.http.middlewares.test-ratelimit.ratelimit.sourcecriterion.requesthost=true"
```

```yaml tab="File (YAML)"
http:
  middlewares:
    test-ratelimit:
      rateLimit:
        sourceCriterion:
          requestHost: true
```

```toml tab="File (TOML)"
[http.middlewares]
  [http.middlewares.test-ratelimit.rateLimit]
    [http.middlewares.test-ratelimit.rateLimit.sourceCriterion]
      requestHost = true
```
