While there are a few additions to the VCL language from varnish-5.0 and varnish-5.1, existing VCL for 5.0 or 5.1 should work without changes on varnish-5.2.
I have pushed varnish-5.2 to Fedora Rawhide. Fedora 27 is in freeze waiting for its GA release now in November, but I will probably push varnish-5.2 to f26 and f27 some time after the the release.
Those who need varnish-5.2 for EPEL may use my COPR repos at https://copr.fedorainfracloud.org/coprs/ingvar/varnish52/. The repos include varnish-5.2 based on the fedora package, matching varnish-modules and an assorted selections of vmods. The packages are compatible with EPEL 6 and 7.
The following vmods are available
Included in varnish-modules:
Packaged separately (COPR only for now):
As always, feedback is warmly welcome. Please report bugs in varnish and varnish-modules via Red Hat’s Bugzilla. Bugs in the vmod packages not yet available in fedora may be reported to me at ingvar(a)redpill-linpro.com.