In this post, I’m demonstrating how a worker could be used to respond to web-requests, and display a static maintenance-mode page whilst a website has been taken offline for deployment (whilst permitting certain IPs to pass through for testing purposes). Obviously, this one example but I thought it would be a neat idea to replace the F5 maintenance iRule I wrote about in a previous post.
An example execution workflow:
- Maintenance mode Worker code deployed to Cloudflare and appropriate routes are created
- Deployment pipe-line begins – PowerShell script calls Cloudflare API and enables the worker for specific routes
- Cloudflare intercepts all requests to my website and instead responds with the static under maintenance page for ALL URL’s
- Deployment pipe-line completes – PowerShell script calls Cloudflare API and disables the worker for specific routes
- Web requests for my website now flow down to the origin infrastructure as per normal
Easy right? Let’s work through the deployment of it.
The rule logic:
The worker rule example is pretty simple! – Intercept the request, If the contents of the cf-connecting-ip header is a trusted IP address then allow them to down to the origin for testing purposes. If cf-connecting-IP is a non-trusted IP address then show the static maintenance page (note the omitted/highlighted images in the example below, see repo for full source):
Deploy the Worker
To deploy the above rule – Select Workers from the Cloudflare admin dashboard under one of your domains and launch the editor:
Add the worker script into the script body.
Select the Routes tab and individually add the routes you want to display the maintenance page on (note you can use wild-cards if required:
Just like Cloudflare’s other services, Workers are able to be configured and controlled using their V4 API – We can toggle the Worker’s status using a simple PowerShell call. e.g:
I’ve published the full source along with a script to toggle the maintenance using PowerShell and the Cloudflare API here https://github.com/coaxke/CloudflareWorkersMaintenance
Workers are pretty powerful, and there’s plenty you can do at Layer7!
- February 22, 2021 @ 14:28:53 [Current Revision] by Sharing Solution
- February 22, 2021 @ 14:28:13 by Sharing Solution
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