The “Expires” and “ETag” in NGINX

The “Expires”in NGINX

We can manage the caching behavior of static resources like pictures, CSS files, and JavaScript files in Nginx by using the “expires” directive. We can tell the client’s browser to cache these resources by giving them an expiration period and preventing pointless server calls. This can reduce server load and increase website performance dramatically.

For static resources that don’t change often, we need to set an expiration date of one month. This implies that unless they are changed, the client’s browser will only make a monthly request to the server for these resources.

To set the “Expires” header in NGINX, we can use the expires directive within the NGINX configuration. For instance,

In this case, the “Expires” header will be set to 7 days from the current date for resources under the /static location.

The “ETag”in NGINX

Nginx uses the “ETag” (entity tag) directive to identify whether a resource is current in the client’s cache. It operates by giving each version of a resource a special identification number. A client transmits the ETag value along with a request for a resource.

The server then makes a comparison between this value and the resource’s most recent ETag value. If they match, the server replies with a 304 Not Modified response, signifying that the client’s cached copy is still valid. By preventing pointless resource transfers, conserves bandwidth and lowers server burden.

The following directive can be used to disable ETags in NGINX:

[Want to learn more? Click here to reach us.]

Conclusion

We can easily manage caching behavior and enhance website performance with Nginx by utilizing the “expires” and “ETag” directives.