Varnish Cache 6.1 Release

The latest release of Varnish Cache (6.1) is now available on section.io, bringing about several new features and stability improvements, albeit minor in the words of Poul-Henning Kamp.

section.io made this version of Varnish Cache available within our platform 2hrs after the source code release, further highlighting the speed and flexibility of the section.io Edge Platform.

Notable Varnish Cache 6.1 Updates

  • Since new users often forget to vcl.discard their old VCLs, they have added a warning when you have more than 100 VCLs loaded. There are parameters to set the threshold and decide what happens when it is exceeded (ignore/warn/error).
  • req.http.Host is now mandatory and requests are handled without it on the fast DoS avoidance path.
  • req.grace had been previously removed, but has been reintroduced, since there are use cases that cannot be solved without it. Similarly, req.ttl used to be deprecated and is now fully supported again.
  • The evaluation of the beresp.keep timer has changed a bit. keep sets a lifetime in the cache in addition to TTL for objects that can be validated by a 304 “Not Modified” response from the backend to a conditional request (with If-None-Match or If-Modified-Since). If an expired object is also out of grace time, then vcl_hit will no longer be called, so it is impossible to deliver the “keep” object in this case.
  • The beresp.filters variable is readable and writable in vcl_backend_response. This is a space-separated list of modules called VFPs, for “Varnish fetch processors”, that may be applied to a backend response body as it is being fetched.
  • obj.hits has been fixed to return the correct value in vcl_hit (it had been 0 in vcl_hit).
  • The Host header in client requests is mandatory for HTTP/1.1, as proscribed by the HTTP standard. If it is missing, then builtin.vcl causes a synthetic 400 “Bad request” response to be returned.

View a complete list of changes and detailed upgrade documentation.

Next Scheduled Varnish Cache Release

According to Poul-Henning, the next Varnish Cache release will take place March 15th 2019, and later this year they will decide whether that version will become 6.2 or 7.0.

If you need assistance upgrading to Varnish Cache 6.1 in your section.io account, we’re here to help. Get in touch

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