Project: Kong (Orchestration & Management / API Gateway)
File: DEVELOPER.md

We encourage community contributions to Kong. To make sure it is a smooth experience (both for you and for the Kong team), please read , , and before you start. If you are planning on developing on Kong, you'll need a development installation. The `master` branch holds the latest unreleased source code. You can read more about writing your own plugins in the [Plugin Development Guide](https://docs.konghq.com/gateway/latest/plugin-development/), or browse an online version of Kong's source code documentation in the [Plugin Development Kit (PDK) Reference](https://docs.konghq.com/latest/pdk/). For a quick start with custom plugin development, check out and the explained in detail below. Kong comes in many shapes. While this repository contains its core's source code, other repos are also under active development: : Use Kong for Kubernetes Ingress. : A Dockerfile for running Kong in Docker. : Pre-built packages for Debian, Red Hat, and OS X distributions (shipped with each release). : Homebrew Formula for Kong. : Kong AMI on the AWS Marketplace. : Run Kong using Azure Resource Manager. : Deploy Kong on Heroku in one click. - How to deploy Kong on IBM Cloud : Let Instaclustr manage your Cassandra cluster. : Docker images for each commit in the `master` branch. You can find every supported distribution on the . is a CLI tool that are specific for plugin development. It is docker-compose based and will create local test environments including all dependencies. Core features are running tests, integrated linter, config initialization, CI support, and custom dependencies. The provides a basic plugin and is considered a best-practices plugin repository. When writing custom plugins, we strongly suggest you start by using this repository as a starting point. It contains the proper file structures, configuration files, and CI setup to get up and running quickly. This repository seamlessly integrates with . This is the hard way to build a development environment, and also a good start for beginners to understand how everything fits together. Kong is mostly an OpenResty application made of Lua source files, but also requires some additional third-party dependencies, some of which are compiled with tweaked options, and kong runs on a modified version of OpenResty with patches. To install from the source, first, we clone the repository: ```shell git clone https://github.com/Kong/kong cd kong git checkout master ``` Then we will install the dependencies: Ubuntu/Debian: ```shell sudo apt update \ && sudo apt install -y \ automake \ build-essential \ curl \ file \ git \ libyaml-dev \ libprotobuf-dev \ m4 \ perl \ pkg-config \ procps \ unzip \ valgrind \ zlib1g-dev ``` Fedora/RHEL: ```shell dnf install \ automake \ gcc \ gcc-c++ \ git \ libyaml-devel \ make \ patch \ perl \ perl-IPC-Cmd \ protobuf-devel \ unzip \ valgrind \ valgrind-devel \ zlib-devel ``` macOS ```shell /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)" brew install libyaml ``` Now, we have to set environment variable `GITHUB_TOKEN` to download some essential repos. You can follow to generate an access

It does not need to have any other permission than `Public Repositories (read-only)`. ```bash ``` Finally, we start the build process: ``` make build-venv ``` contains a troubleshooting section if you face any problems. It also describes the build process in detail, if you want to development on the build system itself. Now you can start Kong: ```shell . bazel-bin/build/kong-dev-venv.sh . bazel-bin/build/kong-dev-venv.fish start_services kong start kong stop deactivate ``` By default, the development environment adds current directory to Lua files search path. Modifying the and directives will allow Kong to find your custom plugin's source code wherever it might be in your system. Install the development dependencies (, ) with: ```shell make dev ``` Kong relies on three test suites using the testing library: Unit tests Integration tests, which require Postgres and Cassandra to be up and running Plugins tests, which require Postgres to be running The first can simply be run after installing busted and running: ``` make test ``` However, the integration and plugins tests will spawn a Kong instance and perform their tests against it. Because these test suites perform their tests against the Kong instance, you may need to edit the `spec/kong_tests.conf` configuration file to make your test instance point to your Postgres/Cassandra servers, depending on your needs. You can run the integration tests (assuming both Postgres and Cassandra are running and configured according to `spec/kong_tests.conf`) with: ``` make test-integration ``` And the plugins tests with: ``` make test-plugins ``` Finally, all suites can be run at once by simply using: ``` make test-all ``` Consult the script for more advanced example usage of the test suites and the Makefile. Finally, a very useful tool in Lua development (as with many other dynamic languages) is performing static linting of your code. You can use \(installed with `make dev`\) for this: ``` make lint ``` Kong Gateway supports no-downtime upgrades through its database schema migration mechanism (see ). Each schema migration needs to be written in a way that allows the previous and the current version of Kong Gateway run against the same database during upgrades. Once all nodes have been upgraded to the current version of Kong Gateway, additional changes to the database can be made that are incompatible with the previous version. To support that, each migration is split into two parts, an `up` part that can only make backwards-compatible changes, and a `teardown` part that runs after all nodes have been upgraded to the current version. Each migration that is contained in Kong Gateway needs to be accompanied with a test that verifies the correct operation of both the previous and the current version during an upgrade. These tests are located in the directory and must be named after the migration they test such that the migration `kong//*.lua` has a test in `spec/05-migration//*_spec.lua`. The presence of a test is enforced by the shell script which is through a GitHub

The shell script works as follows: A new Kong Gateway installation is brought up using , consisting of one node containing the previous version of Kong Gateway ("OLD"), one node containing the current version of Kong Gateway ("NEW") and a shared database server (PostgreSQL or Cassandra). NEW: The database is initialized using `kong migrations bootstrap`. OLD: The `setup` phase of all applicable migration tests is run. NEW: `kong migrations up` is run to run the `up` part of all applicable migrations. OLD: The `oldafterup` phase of all applicable migration tests is run. NEW: The `newafterup` phase of all applicable migration tests is run. NEW: `kong migrations finish` is run to invoke the `teardown` part of all applicable migrations. NEW: The `newafterfinish` phase of all applicable migration tests is run. Upgrade tests are run using . To support the specific testing method of upgrade testing, a number of helper functions are defined in the module. Migration tests use functions from this module to define test cases and associate them with phases of the upgrade testing process. Consequently, they are named `setup`, `oldafterup`, `newafterup` and `newafterfinish`. Additionally, the function `all_phases` can be used to run a certain test in the three phases `oldafterup`, `newafterup` and `newafterfinish`. These functions replace the use of busted's `it` function and accept a descriptive string and a function as argument. It is important to note that upgrade tests need to run on both the old and the new version of Kong. Thus, they can only use features that are available in both versions (i.e. from helpers.lua). The module is copied from the new version into the container of the old version and it can be used to make new library functionality available to migration tests. When developing, you can use the `Makefile` for doing the following operations: | Name | Description | | :| -| | `install` | Install the Kong luarock globally | | `dev` | Install development dependencies | | `lint` | Lint Lua files in `kong/` and `spec/` | | `test` | Run the unit tests suite | | `test-integration` | Run the integration tests suite | | `test-plugins` | Run the plugins test suite | | `test-all` | Run all unit + integration + plugins tests at once | You can follow the steps given below to setup a hybrid mode environment. Activate the venv ```bash ``` Following to generate a certificate/key pair. Create CP and DP configuration files, such as `kong-cp.conf` and `kong-dp.conf`. Following to configure CP using `kong.conf`. Following to configure DP using `kong.conf`. Unset environment variable `KONG_PREFIX` to ensure configuration directive `prefix` in configuration file is enabled. Modify or add the directive `prefix` to `kong-cp.conf` and `kong-dp.conf` to be `prefix=servroot-cp` and `prefix=servroot-dp`, or other names you want, but make sure they are different. Use the pre-defined docker-compose file to bring up databases,

```bash ``` If it is the first time to start Kong, you have to execute the following command to CP node. ```bash ``` Start CP and DP. `kong start -c kong-cp.conf` and `kong start -c kong-dp.conf`. To stop CP and DP, you can execute `kong stop -p servroot-cp` and `kong stop -p servroot-dp` in this example. Names `servroot-cp` and `servroot-dp` are set in configuration file in step 7. If you have a Linux development environment (either virtual or bare metal), the build is done in four separate steps: Development dependencies and runtime libraries, including: Prerequisite packages. Mostly compilers, tools, and libraries required to compile everything else. OpenResty system, including Nginx, LuaJIT, PCRE, etc. Databases. Kong uses Postgres, Cassandra, and Redis. We have a handy setup with docker-compose to keep each on its container. Kong itself. Final deployments are typically on a Linux machine or container, so even if all components are multiplatform, it's easier to use it for development too. If you use macOS or Windows machines, setting up a virtual machine is easy enough now. Most of us use the freely available VirtualBox without any trouble. If you use Linux for your desktop, you can skip this section. There are no "hard" requirements on any Linux distro, but RHEL and CentOS can be more of a challenge to get recent versions of many packages; Fedora, Debian, or Ubuntu are easier for this. To avoid long compilation times, give the VM plenty of RAM (8GB recommended) and all the CPU cores you can. You will need to setup port forwarding on VirtualBox to be able to ssh into the box which can be done as follows: Select the virtual machine you want to use and click "Settings" Click the "Network" tab Click the "Advanced" dropdown Click "Port Forwarding" Add a new rule in the popup. The only thing you will need is "Host Port" to be 22222 and "Guest Port" to be 22. Everything else can be left default (see screenshot below) Click "Ok" Now you should be able to `ssh <your_name>@127.1 -p 22222` to get SSH prompt. However, this requires us to type a long command and password every time we sign in. It is recommended you set up a public key and SSH alias to make this process simpler: On your host machine, generate a keypair for SSH into the guest: `ssh-keygen -t ed25519`. Just keep hitting Enter until the key is generated. You do not need a password for this key file since it is only used for SSH into your guest Type `cat .ssh/id_ed25519.pub` and copy the public key SSH into the guest using the command above Create the ssh config directory (if it doesn't exist) `$ mkdir -p .ssh` Edit the authorized keys list: `vim .ssh/authorized_keys` Paste in the content of .ssh/id_ed25519.pub Adjust the required privileges: `chmod 700 .ssh/` and `chmod 400 .ssh/authorized_keys` Logout of guest and make sure you are not promoted password when SSH again Edit the

file on your host and put in the following content: ``` Host dev HostName 127.1 Port 22222 User <yourusername> ``` Now try `ssh dev` on your host, you should be able to get into the guest directly. The `devcontainer.json` file in Kong's project tells VS Code how to access (or create) a development container with a well-defined tool and runtime stack. See . See . is a plugin for IntelliJ IDEA and VSCode that provides Lua language support. It comes with debugger support that makes it possible to set breakpoints in Lua code and inspect variables. Kong Gateway can be debugged using EmmyLua by following these steps: Download and install IntelliJ IDEA from . Note that IntelliJ is a commercial product and requires a paid license after the trial period. Download and install MS Visual Studio Code from . Go to the `Settings`->`Plugins`->`Marketplace` and search for `EmmyLua`. Install the plugin. Go to the `Settings`->`Extensions` and search for `EmmyLua`. Install the plugin (publisher is `Tangzx`). The is a standalone C++ program that runs on the same machine as Kong Gateway and that mediates between the IDE's debugger and the Lua code running in Kong Gateway. It can be downloaded from . The release ZIP file contains a single share library named emmycore.so (Linux) or emmycore.dylib (macOS). Place this file in a directory that is convenient for you and remember the path. Depending on your Linux version, you may need to compile on your own system as the release binaries published on GitHub assume a pretty recent version of GLIBC to be present. To enable the EmmyLua debugger, the `KONGEMMYDEBUGGER` environment variable must be set to the absolute path of the debugger shared library file when Kong Gateway is started. It is also advisable to start Kong Gateway with only one worker process, as debugging multiple worker processes is not supported. For example: ```shell KONGEMMYDEBUGGER=/path/to/emmycore.so KONGNGINXWORKERPROCESSES=1 kong start ``` Go to `Run`->`Edit Configurations` and click the `+` button to add a new configuration. Select `Emmy Debugger(NEW)` as the configuration type. Enter a descriptive name for the configuration, e.g. "Kong Gateway Debug". Click `OK` to save the configuration. Go to `Run`->`Add Configuration` and choose `EmmyLua New Debugger`. Enter a descriptive name for the configuration, e.g. "Kong Gateway Debug". Save `launch.json`. To connect the EmmyLua debugger to Kong Gateway, click the `Run`->`Debug` menu item in IntelliJ (`Run`->`Start Debugging` in VSCode) and select the configuration that you've just created. You will notice that the restart and stop buttons on the top of your IDE will change to solid green and red colors. You can now set breakpoints in your Lua code and start debugging. Try setting a breakpoint in the global `access` function that is defined `runloop/handler.lua` and send a proxy request to the Gateway. The debugger should stop at the breakpoint and you can inspect the variables in the request context. Refer to the for more information. Learn about . Learn about . Learn about the fork of OpenResty. For profiling, see , the SystemTap framework for OpenResty.