Kong Response Size Limiting

Block upstream responses whose body is greater than a specific size in megabytes.

Proxy consumers will receive an HTTP Status of 413 and message body “Response size limit exceeded” in the event the body is greater than configured size.

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.

Configuration

Enabling the plugin on a Service

With a database

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

$ curl -X POST http://kong:8001/services/{service}/plugins \
    --data "name=kong-response-size-limiting"  \
    --data "config.allowed_payload_size=128"

Without a database

Configure this plugin on a Service by adding this section do your declarative configuration file:

plugins:
- name: kong-response-size-limiting
  service: {service}
  config: 
    allowed_payload_size: 128

In both cases, {service} is the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

With a database

Configure this plugin on a Route with:

$ curl -X POST http://kong:8001/routes/{route}/plugins \
    --data "name=kong-response-size-limiting"  \
    --data "config.allowed_payload_size=128"

Without a database

Configure this plugin on a Route by adding this section do your declarative configuration file:

plugins:
- name: kong-response-size-limiting
  route: {route}
  config: 
    allowed_payload_size: 128

In both cases, {route} is the id or name of the Route that this plugin configuration will target.

Enabling the plugin on a Consumer

With a database

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

$ curl -X POST http://kong:8001/consumers/{consumer}/plugins \
    --data "name=kong-response-size-limiting" \
     \
    --data "config.allowed_payload_size=128"

Without a database

Configure this plugin on a Consumer by adding this section do your declarative configuration file:

plugins:
- name: kong-response-size-limiting
  consumer: {consumer}
  config: 
    allowed_payload_size: 128

In both cases, {consumer} is the id or username of the Consumer that this plugin configuration will target.

You can combine consumer_id and service_id

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

Global plugins

• Using a database, all plugins can be configured using the http://kong:8001/plugins/ endpoint.
• Without a database, all plugins can be configured via the plugins: entry on the declarative configuration file.

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:

Caveat

This plugin currently accomplishes response limiting by validating the Content-Length header on upstream responses. If the upstream lacks the response header, then this plugin will allow the response to pass.

Installation

Recommended:

$ luarocks install kong-response-size-limiting

Other:

$ git clone https://github.com/Optum/kong-response-size-limiting.git /path/to/kong/plugins/kong-response-size-limiting
$ cd /path/to/kong/plugins/kong-response-size-limiting
$ luarocks make *.rockspec

Maintainers

jeremyjpj0916
rsbrisci

Feel free to open issues, or refer to our Contribution Guidelines if you have any questions.