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Response Rate Limiting

This plugin allows you to limit the number of requests a developer can make based on a custom response header returned by the upstream service. You can arbitrary set as many rate-limiting objects (or quotas) as you want and instruct Kong to increase or decrease them by any number of units. Each custom rate-limiting object can limit the inbound requests per seconds, minutes, hours, days, months or years.

If the underlying Service/Route (or deprecated API entity) has no authentication layer, the Client IP address will be used, otherwise the Consumer will be used if an authentication plugin has been configured.

Note: The functionality of this plugin as bundled with versions of Kong prior to 0.13.1 and Kong Enterprise prior to 0.32 differs from what is documented herein. Refer to the CHANGELOG for details.

Terminology

  • plugin: a plugin executing actions inside Kong before or after a request has been proxied to the upstream API.
  • Service: the Kong entity representing an external upstream API or microservice.
  • Route: the Kong entity representing a way to map downstream requests to upstream services.
  • Consumer: the Kong entity representing a developer or machine using the API. When using Kong, a Consumer only communicates with Kong which proxies every call to the said upstream API.
  • Credential: a unique string associated with a Consumer, also referred to as an API key.
  • upstream service: this refers to your own API/service sitting behind Kong, to which client requests are forwarded.
  • API: a legacy entity used to represent your upstream services. Deprecated in favor of Services since CE 0.13.0 and EE 0.32.

Configuration

This plugin is compatible with requests with the following protocols:

  • http
  • https

This plugin is partially compatible with DB-less mode.

The plugin will run fine with the `local` policy (which doesn't use the database) or the `redis` policy (which uses an independent Redis, so it is compatible with DB-less). The plugin will not work with the `cluster` policy, which requires writes to the database.

Enabling the plugin on a Service

Configure this plugin on a Service by making the following request:

$ curl -X POST http://kong:8001/services/{service}/plugins \
    --data "name=response-ratelimiting"  \
    --data "config.limits.{limit_name}=" \
    --data "config.limits.{limit_name}.minute=10"
  • service: the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

Configure this plugin on a Route with:

$ curl -X POST http://kong:8001/routes/{route_id}/plugins \
    --data "name=response-ratelimiting"  \
    --data "config.limits.{limit_name}=" \
    --data "config.limits.{limit_name}.minute=10"
  • route_id: the id of the Route that this plugin configuration will target.

Enabling the plugin on a Consumer

You can use the http://localhost:8001/plugins endpoint to enable this plugin on specific Consumers:

$ curl -X POST http://kong:8001/plugins \
    --data "name=response-ratelimiting" \
    --data "consumer_id={consumer_id}"  \
    --data "config.limits.{limit_name}=" \
    --data "config.limits.{limit_name}.minute=10"

Where consumer_id is the id of the Consumer we want to associate with this plugin.

You can combine consumer_id and service_id

in the same request, to furthermore narrow the scope of the plugin.

Enabling the plugin on an API

If you are using an older version of Kong with the legacy API entity (deprecated in favor of Services since CE 0.13.0 and EE 0.32.), you can configure this plugin on top of such an API by making the following request:

$ curl -X POST http://kong:8001/apis/{api}/plugins \
    --data "name=response-ratelimiting"  \
    --data "config.limits.{limit_name}=" \
    --data "config.limits.{limit_name}.minute=10"
  • api: either id or name of the API that this plugin configuration will target.

Global plugins

All plugins can be configured using the http://kong:8001/plugins/ endpoint. A plugin which is not associated to any Service, Route or Consumer (or API, if you are using an older version of Kong) is considered "global", and will be run on every request. Read the Plugin Reference and the Plugin Precedence sections for more information.

Parameters

Here's a list of all the parameters which can be used in this plugin's configuration:

form parameterdefaultdescription
nameThe name of the plugin to use, in this case response-ratelimiting
service_idThe id of the Service which this plugin will target.
route_idThe id of the Route which this plugin will target.
enabledtrueWhether this plugin will be applied.
consumer_idThe id of the Consumer which this plugin will target.
api_idThe id of the API which this plugin will target. Note: The API Entity is deprecated in favor of Services since CE 0.13.0 and EE 0.32.
config.limits.{limit_name}

This is a list of custom objects that you can set, with arbitrary names set in the {limit_name} placeholder, like config.limits.sms.minute=20 if your object is called “SMS”.
config.limits.{limit_name}.second
semi-optional

The amount of HTTP requests the developer can make per second. At least one limit must exist.
config.limits.{limit_name}.minute
semi-optional

The amount of HTTP requests the developer can make per minute. At least one limit must exist.
config.limits.{limit_name}.hour
semi-optional

The amount of HTTP requests the developer can make per hour. At least one limit must exist.
config.limits.{limit_name}.day
semi-optional

The amount of HTTP requests the developer can make per day. At least one limit must exist.
config.limits.{limit_name}.month
semi-optional

The amount of HTTP requests the developer can make per month. At least one limit must exist.
config.limits.{limit_name}.year
semi-optional

The amount of HTTP requests the developer can make per year. At least one limit must exist.
config.header_name
optional

X-Kong-Limit

The name of the response header used to increment the counters.
config.block_on_first_violation
optional

false

A boolean value that determines if the requests should be blocked as soon as one limit is being exceeded. This will block requests that are supposed to consume other limits too.
config.limit_by
optional

consumer

The entity that will be used when aggregating the limits: consumer, credential, ip. If the consumer or the credential cannot be determined, the system will always fallback to ip.
config.policy
optional

cluster

The rate-limiting policies to use for retrieving and incrementing the limits. Available values are local (counters will be stored locally in-memory on the node), cluster (counters are stored in the datastore and shared across the nodes) and redis (counters are stored on a Redis server and will be shared across the nodes).
config.fault_tolerant
optional

true

A boolean value that determines if the requests should be proxied even if Kong has troubles connecting a third-party datastore. If true requests will be proxied anyways effectively disabling the rate-limiting function until the datastore is working again. If false then the clients will see 500 errors.
config.hide_client_headers
optional

false

Optionally hide informative response headers.
config.redis_host
semi-optional

When using the redis policy, this property specifies the address to the Redis server.
config.redis_port
optional

6379

When using the redis policy, this property specifies the port of the Redis server.
config.redis_password
optional

When using the redis policy, this property specifies the password to connect to the Redis server.
config.redis_timeout
optional

2000

When using the redis policy, this property specifies the timeout in milliseconds of any command submitted to the Redis server.
config.redis_database
optional

0

When using the redis policy, this property specifies Redis database to use.

Configuring Quotas

After adding the plugin, you can increment the configured limits by adding the following response header:

Header-Name: Limit=Value [,Limit=Value]

Since X-Kong-Limit is the default header name (you can optionally change it), it will look like:

X-Kong-Limit: limitname1=2, limitname2=4

That will increment the limit limitname1 by 2 units, and limitname2 by 4 units.

You can optionally increment more than one limit by comma separating the entries. The header will be removed before returning the response to the original client.

Headers sent to the client

When this plugin is enabled, Kong will send some additional headers back to the client telling how many units are available and how many are allowed. For example if you created a limit/quota called “Videos” with a per-minute limit:

X-RateLimit-Limit-Videos-Minute: 10
X-RateLimit-Remaining-Videos-Minute: 9

or it will return a combination of more time limits, if more than one is being set:

X-RateLimit-Limit-Videos-Second: 5
X-RateLimit-Remaining-Videos-Second: 5
X-RateLimit-Limit-Videos-Minute: 10
X-RateLimit-Remaining-Videos-Minute: 10

If any of the limits configured is being reached, the plugin will return a HTTP/1.1 429 status code and an empty body.

Upstream Headers

The plugin will append the usage headers for each limit before proxying it to the upstream service, so that you can properly refuse to process the request if there are no more limits remaining. The headers are in the form of X-RateLimit-Remaining-{limit_name}, like:

X-RateLimit-Remaining-Videos: 3
X-RateLimit-Remaining-Images: 0