Skip to content
Kong Logo | Kong Docs Logo
search
  • We're Hiring!
  • Docs
    • Kong Gateway
    • Kong Konnect
    • Kong Mesh
    • Plugin Hub
    • decK
    • Kubernetes Ingress Controller
    • Insomnia
    • Kuma

    • Docs contribution guidelines
  • Plugin Hub
  • Support
  • Community
  • Kong Academy
Get a Demo Start Free Trial
  • Kong Gateway
  • Kong Konnect
  • Kong Mesh
  • Plugin Hub
  • decK
  • Kubernetes Ingress Controller
  • Insomnia
  • Kuma

  • Docs contribution guidelines
  • 3.2.x (latest)
  • 3.1.x
  • 3.0.x
  • 2.8.x
  • 2.7.x
  • 2.6.x
  • Older Enterprise versions (2.1-2.5)
  • Older OSS versions (2.1-2.5)
  • Archive (pre-2.1)
    • Overview of Kong Gateway
      • Version Support Policy
      • Third Party Dependencies
      • Browser Support
    • Stability
    • Release Notes
      • Services
        • Overview
        • Configure Routes with Expressions
      • Upstreams
      • Plugins
      • Routing Traffic
      • Load Balancing
      • Health Checks and Circuit Breakers
      • Kong Performance Testing
    • Glossary
    • Get Kong
    • Services and Routes
    • Rate Limiting
    • Proxy Caching
    • Key Authentication
    • Load-Balancing
      • Overview
        • Overview
        • Deploy Kong Gateway in Hybrid mode
      • DB-less Deployment
      • Traditional
      • Overview
        • Helm
        • OpenShift with Helm
        • kubectl apply
        • Kubernetes Deployment Options
        • Using docker run
        • Build your own Docker images
        • Amazon Linux
        • Debian
        • Red Hat
        • Ubuntu
      • Running Kong as a non-root user
      • Securing the Admin API
      • Using systemd
      • Start Kong Gateway Securely
      • Programatically Creating Admins
      • Enabling RBAC
      • Overview
      • Download your License
      • Deploy Enterprise License
      • Using the License API
      • Monitor Licenses Usage
      • Default Ports
      • DNS Considerations
      • Network and Firewall
      • CP/DP Communication through a Forward Proxy
        • Configure PostgreSQL TLS
        • Troubleshooting PostgreSQL TLS
    • Kong Configuration File
    • Environment Variables
    • Serving a Website and APIs from Kong
      • Overview
      • Prometheus
      • StatsD
      • Datadog
      • Overview
      • Writing a Custom Trace Exporter
      • Tracing API Reference
    • Resource Sizing Guidelines
    • Security Update Process
    • Blue-Green Deployments
    • Canary Deployments
    • Clustering Reference
      • Log Reference
      • Dynamic log level updates
      • Customize Gateway Logs
      • Upgrade Kong Gateway 3.x.x
      • Migrate from OSS to Enterprise
    • Overview
      • Overview
      • Metrics
      • Analytics with InfluxDB
      • Analytics with Prometheus
      • Estimate Analytics Storage in PostgreSQL
      • Overview
      • Getting Started
      • Advanced Usage
        • Overview
        • Environment Variables
        • AWS Secrets Manager
        • Google Secrets Manager
        • Hashicorp Vault
        • Securing the Database with AWS Secrets Manager
      • Reference Format
      • Overview
      • Get Started with Dynamic Plugin Ordering
      • Overview
      • Enable the Dev Portal
      • Publish an OpenAPI Spec
      • Structure and File Types
      • Themes Files
      • Working with Templates
      • Using the Editor
        • Basic Auth
        • Key Auth
        • OIDC
        • Sessions
        • Adding Custom Registration Fields
        • Manage Developers
        • Developer Roles and Content Permissions
        • Authorization Provider Strategy
        • Enable Application Registration
        • Enable Key Authentication for Application Registration
          • External OAuth2 Support
          • Set up Okta and Kong for External Oauth
          • Set up Azure AD and Kong for External Authentication
        • Manage Applications
        • Theme Editing
        • Migrating Templates Between Workspaces
        • Markdown Rendering Module
        • Customizing Portal Emails
        • Adding and Using JavaScript Assets
        • Single Page App in Dev Portal
        • Alternate OpenAPI Renderer
      • SMTP
      • Workspaces
      • Helpers CLI
      • Portal API Documentation
    • Audit Logging
    • Keyring and Data Encryption
    • Workspaces
    • Consumer Groups
    • Event Hooks
    • Configure Data Plane Resilience
    • About Control Plane Outage Management
      • Overview
      • Install the FIPS Compliant Package
      • FIPS 140-2 Compliant Plugins
    • Overview
    • Enable Kong Manager
      • Services and Routes
      • Rate Limiting
      • Proxy Caching
      • Authentication with Consumers
      • Load Balancing
      • Overview
      • Create a Super Admin
      • Workspaces and Teams
      • Reset Passwords and RBAC Tokens
      • Basic Auth
        • Configure LDAP
        • LDAP Service Directory Mapping
        • Configure OIDC
        • OIDC Authenticated Group Mapping
      • Sessions
        • Overview
        • Enable RBAC
        • Add a Role and Permissions
        • Create a User
        • Create an Admin
    • Networking Configuration
    • Workspaces
    • Create Consumer Groups
    • Sending Email
    • Overview
    • File Structure
    • Implementing Custom Logic
    • Plugin Configuration
    • Accessing the Data Store
    • Storing Custom Entities
    • Caching Custom Entities
    • Extending the Admin API
    • Writing Tests
    • (un)Installing your Plugin
      • Overview
      • kong.client
      • kong.client.tls
      • kong.cluster
      • kong.ctx
      • kong.ip
      • kong.jwe
      • kong.log
      • kong.nginx
      • kong.node
      • kong.request
      • kong.response
      • kong.router
      • kong.service
      • kong.service.request
      • kong.service.response
      • kong.table
      • kong.tracing
      • kong.vault
      • kong.websocket.client
      • kong.websocket.upstream
      • Go
      • Javascript
      • Python
      • Running Plugins in Containers
      • External Plugin Performance
    • Overview
        • Overview
        • OpenID Connect with Curity
        • OpenID Connect with Azure AD
        • OpenID Connect with Google
        • OpenID Connect with Okta
        • OpenID Connect with Auth0
        • OpenID Connect with Cognito
      • Authentication Reference
      • Allow Multiple Authentication Plugins
    • Rate Limiting Plugin
      • Add a Body Value
    • GraphQL
      • gRPC Plugins
      • Configure a gRPC service
    • Overview
    • Information Routes
    • Health Routes
    • Tags
    • Debug Routes
    • Services
    • Routes
    • Consumers
    • Plugins
    • Certificates
    • CA Certificates
    • SNIs
    • Upstreams
    • Targets
    • Vaults
    • Keys
    • Licenses
    • Workspaces
    • RBAC
    • Admins
    • Developers
    • Consumer Groups
    • Event Hooks
    • Keyring and Data Encryption
    • Audit Logs
    • kong.conf
    • Injecting Nginx Directives
    • CLI
    • Key Management
    • Performance Testing Framework
    • Router Expressions Language
    • FAQ

github-edit-pageEdit this page

report-issueReport an issue

enterprise-switcher-iconSwitch to OSS

On this page
  • Install
  • Development
  • Phase handlers
  • PDK functions
  • Plugin dependencies
    • Testing
  • More Information
Kong Gateway
3.2.x (latest)
  • Home
  • Kong Gateway
  • Plugin Development
  • Pluginserver
  • Plugins in Other Languages Javascript

Plugins in Other Languages Javascript

Kong Gateway support for the JavaScript language is provided by the JavaScript PDK. The library provides a plugin server that provides a runtime for JavaScript bindings for Kong Gateway.

TypeScript is also supported in the following ways:

  • The PDK includes type definitions for PDK functions that allow type checking when developing plugins in TypeScript.
  • Plugins written in TypeScript can be loaded directly to Kong Gateway and transpiled.

Install

JavaScript PDK can be installed using npm. To install the plugin server binary globally:

npm install kong-pdk -g

Development

A valid JavaScript plugin implementation should export the following object:

module.exports = {
  Plugin: KongPlugin,
  Schema: [
    { message: { type: "string" } },
  ],
  Version: '0.1.0',
  Priority: 0,
}
  • The Plugin attribute defines the class that implements this plugin.
  • The Schema defines the configuration schema of the plugin.
  • Version and Priority variables set to the version number and priority of execution.

Note: This repository contains examples of plugins built with JavaScript.

Phase handlers

You can implement custom logic to be executed at various points in the request processing lifecycle. To execute custom JavaScript code in the access phase, define a function named access:

class KongPlugin {
  constructor(config) {
    this.config = config
  }
  async access(kong) {
    // ...
  }
}

You can implement custom logic during the following phases using the same function signature:

  • certificate
  • rewrite
  • access
  • response
  • preread
  • log

The presence of the response handler automatically enables the buffered proxy mode.

PDK functions

Kong interacts with the PDK through network-based inter-rocess communication. Each function returns a promise instance. You can use async/await keywords in the phase handlers for better readability.

class KongPlugin {
  constructor(config) {
    this.config = config
  }
  async access(kong) {
    let host = await kong.request.getHeader("host")
    // do something to host
  }
}

Alternatively, use the then method to resolve a promise:

class KongPlugin {
  constructor(config) {
    this.config = config
  }
  async access(kong) {
    kong.request.getHeader("host")
      .then((host) => {
        // do something to host
      })
  }
}

Plugin dependencies

When using the plugin server, plugins are allowed to have extra dependencies, as long as the directory that holds plugin source code also includes a node_modules directory.

Assuming plugins are stored under /usr/local/kong/js-plugins, the extra dependencies are then defined in /usr/local/kong/js-plugins/package.json. Developers also need to run npm install under /usr/local/kong/js-plugins to install those dependencies locally into /usr/local/kong/js-plugins/node_modules.

The Node.js version and architecture that runs the plugin server and the one that runs npm install under plugins directory must match.

Testing

The JavaScript PDK provides a mock framework to test plugin code using jest.

Install jest as a development dependency, then add the test script in package.json:

npm install jest --save-dev

The package.json contains information like this:

{
  "scripts": {
    "test": "jest"
  },
  "devDependencies": {
    "jest": "^26.6.3",
    "kong-pdk": "^0.3.2"
  }
}

Run the test through npm with:

npm test

This repository contains examples of writing tests with jest.

More Information

  • PDK Reference
  • Plugins with Containers
  • Develop plugins with Python
  • Develop plugins with Go
Thank you for your feedback.
Was this page useful?
  • Kong
    THE CLOUD CONNECTIVITY COMPANY

    Kong powers reliable digital connections across APIs, hybrid and multi-cloud environments.

    • Company
    • Customers
    • Events
    • Investors
    • Careers Hiring!
    • Partners
    • Press
    • Contact
  • Products
    • Kong Konnect
    • Kong Gateway
    • Kong Mesh
    • Get Started
    • Pricing
  • Resources
    • eBooks
    • Webinars
    • Briefs
    • Blog
    • API Gateway
    • Microservices
  • Open Source
    • Install Kong Gateway
    • Kong Community
    • Kubernetes Ingress
    • Kuma
    • Insomnia
  • Solutions
    • Decentralize
    • Secure & Govern
    • Create a Dev Platform
    • API Gateway
    • Kubernetes
    • Service Mesh
Star
  • Terms•Privacy
© Kong Inc. 2023