How to configure UDP services with Kong API Gateway

02 Jun, 2022
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Since version 2.2 Kong API Gateway supports UDP services, but the documentation illustrates this with a very complex Kubernetes setup. In this blog I will show you the easiest way to configure a udp service. Without further ado: to configure a UDP service in Kong, you just have to do three things:

  1. define a Kong service with the udp protocol
  2. define a Kong route with the udp protocol
  3. configure Kong to listen on UDP

In this setup, I will configure the Google DNS nameservers as a udp service and route traffic from localport 5353.

define kong udp service

To define the kong UDP service, type:

$ curl -sS --fail \
     -X POST http://localhost:8001/services \
     -d name=google-dns \
     -d protocol=udp \
     -d host= \
     -d port=53

define kong udp route

To define the kong UDP route to the service, type:

curl -sS --fail  \
     -X POST http://localhost:8001/services/google-dns/routes \
     -H 'Content-Type: application/json' \
     -d '{"protocols": [ "udp"], "destinations": [{"port": 5353}]}'

configure Kong to listen on UDP

To configure Kong to listen on UDP, start kong with the property stream_listen set:

KONG_STREAM_LISTEN=" udp" kong ...

Bonus enable logging

The enable logging of udp requests, make you configure the udp protocol on the plugin too.

curl -sS --fail \
    -X POST http://localhost:8001/plugins \
    --data name=file-log \
    --data protocols=udp \
    --data protocols=http \
    --data protocols=https \
    --data config.path=/tmp/request.log


The guide on Using UDP in Kong is more a guide into the complexity of kubernetes. In this blog, I showed you how easy it really is!

Image by Gerd Altmann from Pixabay

Mark van Holsteijn
Mark van Holsteijn is a senior software systems architect at Xebia Cloud-native solutions. He is passionate about removing waste in the software delivery process and keeping things clear and simple.

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