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immutable: NGINX module for setting immutable caching on static assets

Installation

CentOS/RHEL 6, 7, 8 or Amazon Linux 2

bash yum -y install https://extras.getpagespeed.com/release-latest.rpm yum -y install nginx-module-immutable

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

nginx load_module modules/ngx_http_immutable_module.so;

This document describes nginx-module-immutable v0.0.1 released on Feb 24 2020.

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This tiny NGINX module can help improve caching of your public static assets, by setting far future expiration with immutable attribute.

Synopsis

nginx http { server { location /static/ { immutable on; } } }

will yield the following HTTP headers:

... Cache-Control: public,max-age=31536000,immutable Expires: Thu, 31 Dec 2037 23:55:55 GMT ...

How it's different to expires max;:

  • Sets immutable attribute, e.g. Cache-Control: public,max-age=31536000,immutable for improved caching
  • Sends Expires only when it's really necessary, e.g. when a client is requesting resources over HTTP/1.0
  • Sets public attribute to ensure the assets can be cached by public caches, which is typically a desired thing.

Thus in most cases, immutable on; can be used as as a better alternative to expires max;.

Example: Magento 2 production configuration

Provided that your store runs in production mode, you have already compiled all the assets. This sample config can be optimized to:

```nginx location /static/ { immutable on;

# Remove signature of the static files that is used to overcome the browser cache
location ~ ^/static/version {
    rewrite ^/static/(version\d*/)?(.*)$ /static/$2 last;
}

location ~* \.(ico|jpg|jpeg|png|gif|svg|js|css|swf|eot|ttf|otf|woff|woff2|json)$ {
    add_header X-Frame-Options "SAMEORIGIN";
}
location ~* \.(zip|gz|gzip|bz2|csv|xml)$ {
    add_header Cache-Control "no-store";
    add_header X-Frame-Options "SAMEORIGIN";
    immutable off;
}
add_header X-Frame-Options "SAMEORIGIN";

} ```

When used together with ngx_security_headers, it can be simplified further:

``` security_headers on;

location /static/ { immutable on;

location ~ ^/static/version {
    rewrite ^/static/(version\d*/)?(.*)$ /static/$2 last;
}

location ~* \.(zip|gz|gzip|bz2|csv|xml)$ {
    add_header Cache-Control "no-store";
    immutable off;
}

} ```

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-immutable.

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