How to prevent browser caching for merged files?

Question

I'm using magento 2.1.2 in production mode with merge/minify/bundle enabled. It works good and the created files like /static/_cache/merged/6c3c8136610cacb3de381ea2afc99190.min.js has header expires setted to 1y. I think this setting is correct.

The problem is when new js changes are loaded. After flush all magento cache the new merged file contains new js changes correclty, but it has the same name as the old file, so the browser, due to the header expires, doesn't reload it and shows the old version.

To see the new changes i have to force the cache to clear with ctrl+F5.

I think a possible solution could be to give different name to merged file when they have different content or adopt a versioning system.

Do you know how to achieve this?

Answer 1

You can Enable the Sign static files option in system configuration and redeploy static files : Store=>Configuration=>Advanced=>Developer=>Static file signing settings to yes

Make sure that you have correctly set up your webserver.

You can based on the nginx sample configuration or on the htaccess.

Make sure you have this kind of lines :

Nginx:

location /static/ {
    # Uncomment the following line in production mode
    # expires max;

    # 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)$ {
        add_header Cache-Control "public";
        add_header X-Frame-Options "SAMEORIGIN";
        expires +1y;

        if (!-f $request_filename) {
            rewrite ^/static/(version\d*/)?(.*)$ /static.php?resource=$2 last;
        }
    }
    location ~* \.(zip|gz|gzip|bz2|csv|xml)$ {
        add_header Cache-Control "no-store";
        add_header X-Frame-Options "SAMEORIGIN";
        expires    off;

        if (!-f $request_filename) {
           rewrite ^/static/(version\d*/)?(.*)$ /static.php?resource=$2 last;
        }
    }
    if (!-f $request_filename) {
        rewrite ^/static/(version\d*/)?(.*)$ /static.php?resource=$2 last;
    }
    add_header X-Frame-Options "SAMEORIGIN";
}

Apache : pub/static/.htaccess

<IfModule mod_rewrite.c>
    RewriteEngine On

    # Remove signature of the static files that is used to overcome the browser cache
    RewriteRule ^version.+?/(.+)$ $1 [L]

    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-l

    RewriteRule .* ../static.php?resource=$0 [L]
</IfModule>

Answer 2

Enable Sign static files option in system configuration and redeploy static files.