About Kong Plugins

About Kong Plugins

What are plugins?

Kong Gateway is a Lua application designed to load and execute modules, which we commonly refer to as plugins. Plugins provide advanced functionality and extend the use of the Kong Gateway, allowing you to add more features to your implementation.

Kong provides a set of standard Lua plugins that get bundled with Kong Gateway and Konnect. The set of plugins you have access to depends on your license tier.

You can also develop custom plugins, adding your own custom functionality to Kong Gateway.

Scoping plugins

You can run plugins in various contexts, depending on your environment needs. Each plugin can run globally, or be scoped to some combination of the following:

Services
Routes
Consumers
Consumer groups

Using scopes, you can customize how Kong handles functions in your environment, either before a request is sent to your backend services or after it receives a response. For example, if you apply a plugin to a single route, that plugin will trigger only on the specific path requests take through your system. On the other hand, if you apply the plugin globally, it will run on every request, regardless of any other configuration.

Global scope

A global plugin is not associated to any service, route, consumer, or consumer group is considered global, and will be run on every request, regardless of any other configuration.

In self-managed Kong Gateway Enterprise, the plugin applies to every entity in a given workspace.
In self-managed Kong Gateway (OSS), the plugin applies to your entire environment.
In Konnect, the plugin applies to every entity in a given control plane.

Every plugin supports a subset of these scopes.

See the scope compatibility reference for all supported scopes for each plugin.

Precedence

A single plugin instance always runs once per request. The configuration with which it runs depends on the entities it has been configured for. Plugins can be configured for various entities, combinations of entities, or even globally. This is useful, for example, when you want to configure a plugin a certain way for most requests but make authenticated requests behave slightly differently.

Therefore, there is an order of precedence for running a plugin when it has been applied to different entities with different configurations. The number of entities configured to a specific plugin directly correlates to its priority. The more entities a plugin is configured for, the higher its order of precedence.

The complete order of precedence for plugins configured to multiple entities is:

Consumer + route + service: Highest precedence, affecting authenticated requests that match a specific consumer on a particular route and service.
Consumer group + service + route: Affects groups of authenticated users across specific services and routes.
Consumer + route: Targets authenticated requests from a specific consumer on a particular route.
Consumer + service: Applies to authenticated requests from a specific consumer accessing any route within a given service.
Consumer group + route: Affects groups of authenticated users on specific routes.
Consumer group + service: Applies to all routes within a specific service for groups of authenticated users.
Route + service: Targets all consumers on a specific route and service.
Consumer: Applies to all requests from a specific, authenticated consumer across all routes and services.
Consumer group: Affects all routes and services for a designated group of authenticated users.
Route: Specific to given route.
Service: Specific to given service.
Globally configured plugins: Lowest precedence, applies to all requests across all services and routes regardless of consumer status.

Note on precedence for consumer groups: When a consumer is a member of two consumer groups, each with a scoped plugin, Kong Gateway ensures deterministic behavior by executing only one of these plugins. However, the specific rules that govern this behavior are not defined and are subject to change in future releases.

Plugin compatibility with deployment types

Kong Gateway can be deployed in a variety of ways, and not all plugins are fully compatible with each mode. See Plugin Compatibility for a comparison.

Custom plugins

Developing custom plugins

Kong provides an entire development environment for developing plugins, including Plugin Development Kits (or PDKs), database abstractions, migrations, and more.

Plugins consist of modules interacting with the request/response objects or streams via a PDK to implement arbitrary logic. Kong provides PDKs in the following languages:

These PDKs are sets of functions that a plugin can use to facilitate interactions between plugins and the core (or other components) of Kong.

To start creating your own plugins, review the Getting Started documentation, or see the following references:

Third-party plugins

Through partnerships with third parties, Kong lists some third-party custom plugins on the Kong Plugin Hub. These plugins are maintained by Kong partners. If you would like to have your plugin featured on the Kong Plugin Hub, we encourage you to become a Kong Partner.

Overview