Route requests to different Upstreams based on headers

Uses: Kong Gateway decK

Deployment Platform:

Prerequisites

Kong Konnect

This is a Konnect tutorial. If you don’t have a Konnect account, you can get started quickly with our onboarding wizard.

The following Konnect items are required to complete this tutorial:
- Personal access token (PAT): Create a new personal access token by opening the Konnect PAT page and selecting Generate Token.
- Control Plane Name: You can use an existing Control Plane or create a new one to use for this tutorial.
- Konnect Proxy URL: By default, a self-hosted Data Plane uses http://localhost:8000. You can set up Data Plane nodes for your Control Plane from the Gateway Manager in Konnect.

Set the personal access token, the Control Plane name, the Control Plane URL, and the Konnect proxy URL as environment variables:

 export DECK_KONNECT_TOKEN='YOUR KONNECT TOKEN'
 export DECK_KONNECT_CONTROL_PLANE_NAME='YOUR CONTROL PLANE NAME'
 export KONNECT_CONTROL_PLANE_URL=https://us.api.konghq.com
 export KONNECT_PROXY_URL='KONNECT PROXY URL'

Kong Gateway running

This tutorial requires Kong Gateway Enterprise. If you don’t have Kong Gateway set up yet, you can use the quickstart script with an enterprise license to get an instance of Kong Gateway running almost instantly.

Export your license to an environment variable:

 export KONG_LICENSE_DATA='LICENSE-CONTENTS-GO-HERE'

Run the quickstart script:

 curl -Ls https://get.konghq.com/quickstart | bash -s -- -e KONG_LICENSE_DATA 

Once Kong Gateway is ready, you will see the following message:

 Kong Gateway Ready

decK

decK is a CLI tool for managing Kong Gateway declaratively with state files. To complete this tutorial you will first need to install decK.

Required entities

For this tutorial, you’ll need Kong Gateway entities, like Gateway Services and Routes, pre-configured. These entities are essential for Kong Gateway to function but installing them isn’t the focus of this guide. Follow these steps to pre-configure them:

Run the following command:

echo '
_format_version: "3.0"
services:
  - name: example-service
    url: http://httpbin.konghq.com/anything
routes:
  - name: example-route
    paths:
    - "/anything"
    service:
      name: example-service
' | deck gateway apply -

To learn more about entities, you can read our entities documentation.

Create two Upstreams

In this example, we’ll route requests based on a location header where the value can be either us-east or us-west. We’ll create one Upstream for each location:

echo '
_format_version: "3.0"
upstreams:
  - name: east-upstream
    targets:
    - target: httpbingo.org:80
      weight: 100
  - name: west-upstream
    targets:
    - target: httpbun.com:80
      weight: 100
' | deck gateway apply -

Enable the Route by Header plugin on the Service

Enable the Route by Header plugin on the Gateway Service we created in the prerequisites to route requests with the us-east header value to east-upstream and requests with the us-weast value to west-upstream. Note that this will override the URL defined in the Service configuration.

echo '
_format_version: "3.0"
plugins:
  - name: route-by-header
    service: example-service
    config:
      rules:
      - upstream_name: east-upstream
        condition:
          location: us-east
      - upstream_name: west-upstream
        condition:
          location: us-west
' | deck gateway apply -

Validate

To validate, you can try sending requests with both header values and check the host in the response.

This request is routed to httpbingo.org:

curl "$KONNECT_PROXY_URL/anything" \
     -H "location:us-east"

curl "http://localhost:8000/anything" \
     -H "location:us-east"

This request is routed to httpbun.com:

curl "$KONNECT_PROXY_URL/anything" \
     -H "location:us-west"

curl "http://localhost:8000/anything" \
     -H "location:us-west"

If you send a request without the header, or with a header value not specified in the Route by Header plugin, the request will be routed to the URL defined in the Service configuration, httpbin.konghq.com in this example:

curl "$KONNECT_PROXY_URL/anything" \
     -H "location:eu-west"

curl "http://localhost:8000/anything" \
     -H "location:eu-west"

Cleanup

Clean up Konnect environment

If you created a new control plane and want to conserve your free trial credits or avoid unnecessary charges, delete the new control plane used in this tutorial.

Destroy the Kong Gateway container

curl -Ls https://get.konghq.com/quickstart | bash -s -- -d