Python

Requirements

Since v2.9, Tyk supports any currently stable Python 3.x version. The main requirement is to have the Python shared libraries installed. These are available as libpython3.x in most Linux distributions.

• Python3-dev
• Protobuf: provides Protocol Buffers support
• gRPC: provides gRPC support

Important Note Regarding Performance

Python plugins are embedded within the Tyk Gateway process. Tyk Gateway integrates with Python custom plugins via a cgo bridge.

Tyk Gateway <-> CGO <-> Python Custom Plugin

In order to integrate with Python custom plugins, the libpython3.x.so shared object library is used to embed a Python interpreter directly in the Tyk Gateway. Further details can be found here

This allows combining the strengths of both Python and Go in a single application. However, it’s essential to be aware of the potential complexities and performance implications of mixing languages, as well as the need for careful memory management when working with Python objects from Go.

The Tyk Gateway process initialises the Python interpreter using Py_initialize. The Python Global Interpreter Lock (GIL) allows only one thread to execute Python bytecode at a time, ensuring thread safety and simplifying memory management. While the GIL simplifies these aspects, it can limit the scalability of multi-threaded applications, particularly those with CPU-bound tasks, as it restricts parallel execution of Python code.

In the context of custom Python plugins, API calls are queued and the Python interpreter handles requests sequentially, processing them one at a time. Subsequently, this would consume large amounts of memory, and network sockets would remain open and blocked until the API request is processed.

Install the Python development packages

If you’re using Ubuntu/Debian:

apt install python3 python3-dev python3-pip build-essential

If you’re using Red Hat or CentOS:

yum install python3-devel python3-setuptools
python3 -m ensurepip

Install the Required Python Modules

Make sure that “pip” is now available in your system, it should be typically available as “pip”, “pip3” or “pipX.X” (where X.X represents the Python version):

pip3 install protobuf grpcio

Python versions

Newer Tyk versions provide more flexibility when using Python plugins, allowing the users to set which Python version to use. By default, Tyk will try to use the latest version available.

To see the Python initialisation log, run the Tyk gateway in debug mode.

To use a specific Python version, set the python_version flag under coprocess_options in the Tyk Gateway configuration file (tyk.conf).

Troubleshooting

To verify that the required Python Protocol Buffers module is available:

python3 -c 'from google import protobuf'

No output is expected from this command on successful setups.

How do I write Python Plugins?

We have created a demo Python plugin repository.

The project implements a simple middleware for header injection, using a Pre hook (see Tyk custom middleware hooks. A single Python script contains the code for it, see middleware.py.