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
  • Developing Go plugins
  • Overview
  • Configuration
    • Struct
    • The New() constructor
    • The main() function
    • Phase handlers
    • Version and priority
  • Example configuration
  • More information
Kong Gateway
3.2.x (latest)
  • Home
  • Kong Gateway
  • Plugin Development
  • Pluginserver
  • Write plugins in Go

Write plugins in Go

Developing Go plugins

Kong Gateway supports the Go language with the Go PDK, a library that provides Go bindings for Kong Gateway.

Overview

To write a Kong Gateway plugin in Go, you need to:

  1. Define a structure type to hold configuration.
  2. Write a New() function to create instances of your structure.
  3. Add methods to that structure to handle phases.
  4. Include the go-pdk/server sub-library.
  5. Add a main() function that calls server.StartServer(New, Version, Priority).
  6. Compile as an executable with go build.

Note: The Kong Go plugins repository contains example Go plugins.

Configuration

Struct

The plugin you write needs a way to handle incoming configuration data from the data store or the Admin API. You can use a struct to create a schema of the incoming data.

type MyConfig struct {
    Path   string
    Reopen bool
}

Because this plugin will be processing configuration data, you are going to want to control encoding using the encoding/json package. Go fields that start with a capital letter can be exported, making them accessible outside of the current package, including by the encoding/json package. If you want the fields to have a different name in the data store, add tags to the fields in your struct.

type MyConfig struct {
    Path   string `json:"my_file_path"`
    Reopen bool   `json:"reopen"`
}

The New() constructor

The plugin must define a function called New. This function should instantiate the MyConfig struct and return it as an interface.

func New() interface{} {
    return &MyConfig{}
}

The main() function

Each plugin is compiled as a standalone executable. Include github.com/Kong/go-pdk in the imports list, and add a main() function:

func main () {
  server.StartServer(New, Version, Priority)
}

Executables can be placed somewhere in your path (for example, /usr/local/bin). The common -h flag shows a usage help message:

my-plugin -h

Output:

Usage of my-plugin:
  -dump
        Dump info about plugins
  -help
        Show usage info
  -kong-prefix string
        Kong prefix path (specified by the -p argument commonly used in the Kong CLI) (default "/usr/local/kong")

When you run the plugin without arguments, it creates a socket file within the kong-prefix and the executable name, appending .socket. For example, if the executable is my-plugin, the socket file would be /usr/local/kong/my-plugin.socket.

Phase handlers

In Kong Gateway Lua plugins, you can implement custom logic to be executed at various points of the request processing lifecycle. For example, to execute custom Go code during the access phase, create a function named Access with the following function signature:

func (conf *MyConfig) Access (kong *pdk.PDK) {
  ...
}

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.

Version and priority

You can define the version number and priority of execution by declaring the following constants within the plugin code:

const Version = "1.0.0"
const Priority = 1

Kong Gateway executes plugins from highest priority to lowest.

Example configuration

To load plugins using the kong.conf configuration file, you have to map existing Kong Gateway properties to aspects of your plugin. Here are two examples of loading plugins within kong.conf:

pluginserver_names = my-plugin,other-one

pluginserver_my_plugin_socket = /usr/local/kong/my-plugin.socket
pluginserver_my_plugin_start_cmd = /usr/local/bin/my-plugin
pluginserver_my_plugin_query_cmd = /usr/local/bin/my-plugin -dump

pluginserver_other_one_socket = /usr/local/kong/other-one.socket
pluginserver_other_one_start_cmd = /usr/local/bin/other-one
pluginserver_other_one_query_cmd = /usr/local/bin/other-one -dump

The socket and start command settings coincide with their defaults and can be omitted:

pluginserver_names = my-plugin,other-one
pluginserver_my_plugin_query_cmd = /usr/local/bin/my-plugin -dump
pluginserver_other_one_query_cmd = /usr/local/bin/other-one -dump

More information

  • PDK Reference
  • Plugins with Containers
  • Develop plugins with Python
  • Develop plugins with JavaScript
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