Configure a fallback Route

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.

Validate existing routing rules

In the prerequisites, you configured a Gateway Service and a Route. Let’s check that the Route works by accessing httpbin’s /anything Service, which will echo back the request:

curl -i "$KONNECT_PROXY_URL/anything"

curl -i "http://localhost:8000/anything"

You should get a 200 response back.

Now try to access the same proxy URL, but at the root path (/):

curl -i "$KONNECT_PROXY_URL/"

curl -i "http://localhost:8000/"

The request will fail with the message no Route matched with those values.

Create a fallback Gateway Service and Route

To avoid 404 errors, create a fallback Gateway Service and a Route with the path /. Together, they’ll catch any paths that don’t match other routing rules and redirect them to the Gateway Service URL.

Based on routing priority rules, this Route has the lowest priority and is evaluated after all other Routes because it’s the shortest and covers the broadest range of possible paths.

echo '
_format_version: "3.0"
services:
  - name: fallback_service
    url: http://httpbun.com
routes:
  - name: fallback_route
    service:
      name: fallback_service
    paths:
    - "/"
' | deck gateway apply -

Since all URIs are prefixed by the root character /, if incoming HTTP requests match no other existing Routes, they will match this Route and redirect to the http://httpbun.com Gateway Service URL.

Validate the fallback Route

Try accessing the / path again:

curl -i "$KONNECT_PROXY_URL/"

curl -i "http://localhost:8000/"

This time, the request passes with a 302, and the request is redirected to the fallback Service URL. You should see the header Location: https://httpbun.com/ in the response.

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

FAQs

When should I use the Route entity for fallback routing, and when should I set up redirects with the Redirect plugin instead?

The fallback routing method has limited flexibility. It’s most useful as a blanket rule.

The Redirect plugin gives you more control over your redirect rules. You can apply the Redirect plugin to any Gateway Service, Route, Consumer, or Consumer Group, as well as globally, and you can decide whether the incoming request path remains the same, while still redirecting to a different location.