Category X-Magento-Tags too long causing Varnish to 503

[djfordz]

I have a customer site that Varnish is 503'ing on Category pages that have a too long X-Magento-Tags similar to this issue here: #6401.

Preconditions

1. Magento 2.1.3
2. CentOS 6
3. Mysql Ver 14.14 Distrib 5.6.32-78.1
4. PHP 7.0.16

Steps to reproduce

1. Enable Varnish for page cache
2. Add over 5000 categories greater than 4 levels deep each level with hundreds more categories
3. try to goto category page

Expected result

1. Category Page displays

Actual result

1. [Screenshot, logs]
   503 Varnish Cache Error
   

[ljrweb]

I ran into this problem and I think Magento updated documentation to explain how to extend the parameter value in the varnish config.

http://devdocs.magento.com/guides/v2.0/config-guide/varnish/tshoot-varnish-503.html

[dcabrejas]

I have encountered this issue on a Magento site running on 2.1.5. Category pages containing a large number of products return aX-Magento-Tag header which is bigger than the size allowed by the HTTP specification.

We have implemented this workaround for now http://devdocs.magento.com/guides/v2.0/config-guide/varnish/tshoot-varnish-503.html

But this is not a solution, just a workaround because the http header size is still larger than the limit set by the HTTp specification.