A somewhat similar question: what do you do with frontend assets? If you have JS/CSS/image files with a cache-busting URL, and you have different versions on different servers, you can run into problems.
For example, if most of your web servers are running version 1 and you're in the middle of rolling out version 2. A page request goes to one of the web servers with version 2, which returns HTML containing links to assets with the version 2 cache-busting URLs. The browser requests those assets, perhaps through the CDN, but the load balancer sends the requests to a web server still running version 1, where the assets don't exist yet. This means the browser will get a 404 error.
What are the best options for dealing with this problem?
For example, if most of your web servers are running version 1 and you're in the middle of rolling out version 2. A page request goes to one of the web servers with version 2, which returns HTML containing links to assets with the version 2 cache-busting URLs. The browser requests those assets, perhaps through the CDN, but the load balancer sends the requests to a web server still running version 1, where the assets don't exist yet. This means the browser will get a 404 error.
What are the best options for dealing with this problem?