Triggering Jenkins Parameterized Builds Behind A Firewall

Background

In this post I would like to share with you the process of how to trigger Jenkins parameterized builds behind a firewall.

Imagine your Jenkins is behind a corporate firewall but still able to receive webhooks from Github, DockerHub and Microsoft Automate.

I have seen many posts discussing related topics, but most webhook forwarding services cannot forward query parameters, which means they do not have the ability to trigger Jenkins builds with parameters.

Prerequisites

• Webhook Relay account - register here.
• Jenkins server

Process

Configuring Webhook Relay

Create a New Bucket here . Buckets allow you to group inputs and outputs.

A newly created bucket will have a default input and you will need to create an output destination where webhooks will be sent.

Click on OUTPUT DESTINATION> Fill in your custom Output name > Fill in your Jenkins server address in Output destination > click create output

# Output Destination Example
# If your Jenkins allows anonymous users can have build access.
http://192.168.0.200:8080
# If only authenticated users can have build access.
http://username:token@192.168.0.200:8080

Click CONFIGURE under your Output Destinations > Switch off Lock destination path > Click on SAVE.

It will allow us to send any extra path.
(xyz.hooks.webhookrelay.com/foo/bar -> 192.168.0.200:8080/foo/bar)

Configuring Webhookrelayd agent

Create an access token here. Access tokens are used to authenticate Webhook Relay agents.

On the Jenkins VM or a VM that can talk on the Jenkins server, start a webhookrelayd agent.

Specify configuration through environment variables:

KEY=<your token key>
SECRET=<your token secret>
BUCKET=<bucket name>

Run the webhookrelayd container:

docker run -d \
           --name webhookrelayd \
           --restart=unless-stopped \
           webhookrelay/webhookrelayd 

Now go back to your Bucket page, you should see the status has changed to Client Connected. If there are any problems, you should check your docker logs.

Testing Jenkins Builds

Open your Terminal, let us test your Jenkins build.

Here is an example when trigger the Jenkins build normally:

curl http://192.168.0.200:8080/job/demo/buildWithParameters?token=<buildToken>&env=dev&version=20210804&user=john.doe

When using Webhook Relay, it will be converted to the following url:

curl https://<unique domain>.hooks.webhookrelay.com/job/demo/buildWithParameters?token=<buildToken>&env=dev&version=20210804&user=john.doe

You can also find the Relay Logs here.