Couper Documentation

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Rate Limit (Beta)

Rate limiting protects backend services. It implements quota management used to avoid cascading failures or to spare resources.

Block name	Context	Label
`beta_rate_limit`	named `backend` block	no label

Attributes

Name	Type	Default	Description
`mode`	string	`"wait"`	If `mode` is set to `block` and the rate limit is exceeded, the client request is immediately answered with HTTP status code `429` (Too Many Requests) and no backend request is made. If `mode` is set to `wait` and the rate limit is exceeded, the request waits for the next free rate limiting period.
`per_period`	number	-	Defines the number of allowed backend requests in a period.
`period`	duration	-	Defines the rate limit period.
`period_window`	string	`"sliding"`	Defines the window of the period. A `fixed` window permits `per_period` requests within `period` after the first request to the parent backend. After the `period` has expired, another `per_period` request is permitted. The sliding window ensures that only `per_period` requests are sent in any interval of length `period`.

Duration

Values of type duration are provided as number string followed by a unit listed below.

Example: timeout = "300s"

Duration units	Description
`ns`	nanoseconds
`us` (or `µs`)	microseconds
`ms`	milliseconds
`s`	seconds
`m`	minutes
`h`	hours