Can't purge static assets in Varnish from Magento

[joeshelton-wagento]

Preconditions

Default install in developer mode with Varnish enabled and configured properly. Browser cache disabled

Steps to reproduce

1. Load a page in the browser and ensure Varnish cache has cached static assets like .css, .js
2. Run bin/magento cache:clean full_page
3. Load the same page as step 1 and observe the cache behavior on static assets

Expected result

Static assets would have a Varnish cache miss due to full_page cache being previously cleared

Actual result

Static assets are cache hits. (Non-static assets cleared properly.)

Due to the existing VCL section on purging, static assets can't be purged using the Magento application. Only resources with the X-Magento-Tags-Pattern header will ever be purged by the existing conditional. Static assets will never have this header.

    if (req.method == "PURGE") {
        if (!req.http.X-Magento-Tags-Pattern) {
            return (synth(400, "X-Magento-Tags-Pattern header required"));
        }
        ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
        return (synth(200, "Purged"));
    }

Recommend adding something that clears all cached resources when a "purge all" request is made by Magento.

    if (req.method == "PURGE") {
        if (!req.http.X-Magento-Tags-Pattern) {
            return (synth(400, "X-Magento-Tags-Pattern header required"));
        }
        if (req.http.X-Magento-Tags-Pattern == ".*") {
            ban("req.url ~ /");
        } else {
            ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
        }
        return (synth(200, "Purged"));
    }