ESI rendering for complex CMS components

[ppodgorsek]

A new boolean attribute ("esiRendering") should be added on CMS components: when this attribute is true, components should not be rendered inside the page referencing them. Instead, an ESI fragment should be declared in lieu of it.

That fragment should have the following format:

https://<domain name>:<port>/<application context>/esi-cache/<component label>?<additional parameters>

The additional parameters could include information such as the user/group/segment which should be used to render the component.

A Varnish configuration file should also be provided to match this configuration. The grace period should be extremely long by default.
The documentation should clearly state that only Varnish should be allowed to access that cached URL, it should be blocked for all requests originating from outside of the datacentre.

Furthermore, Varnish fragments should have their own filter chain to avoid going through the StorefrontFilter as the latter is user-dependent.

https://github.com/ppodgorsek/easy-esi can be used to speed up the development work.
https://github.com/ppodgorsek/juncacher can be used to invalidate the component once it has been modified.