.. _whatsnew_changes_7.2:
%%%%%%%%%%%%%%%%%%%%%%
Changes in Varnish 7.2
%%%%%%%%%%%%%%%%%%%%%%
For information about updating your current Varnish deployment to the
new version, see :ref:`whatsnew_upgrading_7.2`.
A more detailed and technical account of changes in Varnish, with
links to issues that have been fixed and pull requests that have been
merged, may be found in the `change log`_.
.. _change log: https://github.com/varnishcache/varnish-cache/blob/master/doc/changes.rst
varnishd
========
Extensions
~~~~~~~~~~
From the very first days of Varnish, we have been talking about having
an extension points for "more advanced stuff" and we did, by and large,
keep a place ready for it in the overall architecture.
Now a credible use-case finally appeared, and we have implemented
"Varnish Extensions" (VTLA: "VEXT"), which can both be used to load
ambient VMODs and to implement entirely new functionality, for instance
stevedores.
See :ref:`ref-vext` in the reference manual for more information.
Parameters
~~~~~~~~~~
Duration values (with a unit in seconds) can optionally take a duration
unit with the same syntax as VCL. For example, the default values of
``default_ttl``, ``default_grace`` and ``default_keep`` were changed
respectively from ``120.000``, ``10.000`` and ``0.000`` to ``2m``, ``10s``
and ``0s``.
The platform-dependent ``tcp_keepalive_time`` parameter is supported on
macOS.
The new ``vcc_feature`` bits parameter replaces previous ``vcc_*`` boolean
parameters. The latter still exist as deprecated aliases.
Other changes in varnishd
~~~~~~~~~~~~~~~~~~~~~~~~~
The metadata VMODs exposes to Varnishd has changed to a non-binary
format, and it is incompatible with all previous releases.
That makes it possible for the VCC (compilation) process to avoid
opening the VMODs with ``dlopen(3)``, which is both faster and
safer.
Background fetch tasks are no longer queued as this could result in slow
grace hits subject to indefinite delays when thread pools are saturated.
Changes to VCL
==============
VCL variables
~~~~~~~~~~~~~
ESI sub-requests can no longer inherit a ``req.http.transfer-encoding``
header since the request body is strictly handled by the top request.
The ``resp.http.via`` header generated by Varnish uses ``server.identity``
which defaults to the host name. A ``req.http.via`` header is generated
also before entering ``vcl_recv``. If a client request or backend response
already had a Via header, it is now appended to instead of overwritten.
A ``resp.http.via`` header is no longer overwritten by varnish, but
rather appended to.
The ``server.identity`` variable is guaranteed to be a single token as
defined in the HTTP grammar, to safely be used as either a host name or
pseudonym in Via headers.
The ``now`` variable remains constant in a VCL subroutine. This was already
the case, but is now (pun intended) formally defined behavior. It keeps the
same value even if the execution blocks for a significant time, for example
while calling a VMOD function.
Bundled VMODs
=============
For a real time timestamp, the function ``std.now()`` can be used instead.
There is also a new ``std.timed_call()`` to measure the execution time of a
subroutine.
Cookie headers generated by vmod_cookie no longer have a spurious trailing
semi-colon (``';'``) at the end of the string.
varnishlog
==========
The ``Begin`` log records may contain a 4th field with the sub-level of
sub-tasks. The ``Begin[4]`` field is used by the ``-E`` option (or lack
thereof) in log utilities to include sub-tasks or not. Internally, only ESI
tasks are subject to this filtering, but it can apply to tasks spawned by
VMODs too.
Similarly, the ``Link`` record has the same optional 4th field.
.. XXX: any reason against ``varnish{hist,top} -k``?
The ``-k`` option from ``varnishlog`` is now available in ``varnishncsa``.
varnishstat
===========
The unused counter ``MAIN.fetch_no_thread`` was repurposed and renamed to
``MAIN.bgfetch_no_thread`` to signal when background fetch tasks fail to
be scheduled because thread pools are saturated.
To help estimate the rate of ``vsl_space`` consumption, the new counter
``MAIN.shm_bytes`` was added. It offers a finer-grained metric than the
existing ``MAIN.shm_cycles`` that depends on the ``vsl_space`` setting.
A new contribution script called ``varnishstatdiff`` can be used to compare
the output of two ``varnishstat -1`` executions with a friendly diff format
for ``varnishstat``'s specific output.
varnishtest
===========
New macros ``${pkg_version}`` and ``${pkg_branch}`` expanding respectively
to ``7.2.0`` and ``7.2`` for the current release.
It is possible to match the text on screen against a regular expression
with the new ``process -match`` command.
The new ``filewrite [-a]`` command can put or append text into a file.
A Varnish instance name in a VTC is used by default as the server identity
for predictable Via headers.
For example::
varnish v1 -vcl+backend { ... }
The expected Via header is::
Via: 1.1 v1 (Varnish/7.2)
The instance name can still be set to a different value using the ``-arg``
command to change the ``varnishd -i`` option.
Changes for developers and VMOD authors
=======================================
The ``varnishtest -i`` option only works from a Varnish source tree, in
which case the new macro ``${topsrc}`` is available in addition to the
old ``${topbuild}`` macro.
The functions ``VRT_AddVDP()``, ``VRT_AddVFP()``, ``VRT_RemoveVDP()`` and
``VRT_RemoveVFP()`` are deprecated.
The ``VCS_String()`` function can take the string ``"B"`` for the package
branch.
The ``vnum.h`` functions are exposed to VMOD and VEXT authors.
The termination rules for ``WRK_BgThread()`` were relaxed to allow VMODs to
use it.
*eof*
Henceforth, whatever our philosopher says about Matter will apply to extension and to extension alone. It cannot be apprehended by sight, nor by hearing, nor by smell, nor by taste, for it is neither colour, nor sound, nor odour, nor juice. Neither can it be touched, for it is not a body, but it becomes corporeal on being blended with sensible qualities. And, in a later essay, he describes it as receiving all things and letting them depart again without retaining the slightest trace of their presence.483 Why then, it may be asked, if Plotinus meant extension, could he not say so at once, and save us all this trouble in hunting out his meaning? There were very good reasons why he should not. In the first place, he wished to express himself, so far as possible, in Aristotelian phraseology, and this was incompatible with the reduction of Matter to extension. In the next place, the idea of an infinite void had been already appropriated by the Epicureans, to whose system he was bitterly opposed. And, finally, the extension of ordinary327 experience had not the absolute generality which was needed in order to bring Matter into relation with that ultimate abstraction whence, like everything else, it has now to be derived. That the millionaire was genuine, ¡°in person and not a caricature,¡± as Dick put it, was evident. Both the nurse, his relative, and his wife, were chatting with him as Jeff delivered the heavy packed ball made up of the gum. 233 "I guess not," said Landor, tolerantly, as he turned[Pg 106] his horse over to his orderly; "but, anyway," he added to Ellton, "we had a picnic¡ªof a sort." Si, unable to think of anything better, went with him. The train had stopped on a switch, and seemed likely to rust fast to the rails, from the way other trains were going by in both directions. The bridge gang, under charge of a burly, red-faced young Englishman, was in the rear car, with their tools, equipments, bedding and cooking utensils. THE DEACON HAS SOME EXPERIENCES WITH THE QUADRUPED. "You are not within a mile of the truth. I know it. Look here: I believe that is Gen. Rosecrans's own cow. She's gone, and I got an order to look around for her. I've never seen her, but from the description given me I believe that's she. Who brought her here?" "Deacon, these brothers and sisters who have come here with me to-night are, like myself, deeply interested in the moral condition of the army, where we all have sons or kinsmen. Now, can't you sit right there and tell us of your observations and experiences, as a Christian man and father, from day to day, of every day that you were down there? Tell us everything, just as it happened each day, that we may be able to judge for ourselves." HAS AN ENCOUNTER WITH THE PROVOST-MARSHAL. "Wonder which one o' them is the 200th Injianny's?" said Si to Shorty. "And your mother, and Harry?" The daughter must be the girl who was talking to him now. She sat on a little stool by the fire, and had brought out some sewing. "Over at Grandturzel¡ªcan't see wot's burning from here. Git buckets and come!" These things, however, gave little concern to the worthy who commanded the Kentish division. Tyler, though an excellent blacksmith, possessed few of the qualities requisite for forming a good general. Provided there was no very sensible diminution in the number of his followers, he cared not a straw for the score or two who, after quarrelling, or perhaps fighting, withdrew in such disgust that they vowed rather to pay the full tax for ever than submit to the insolence of the rebels. One man could fight as well as another, reasoned he; and, provided he was obeyed, what mattered it by whom. Dick went and Tom came¡ªit was sure to be all one in the end. But this burst of indignation soon passed away, and upon the suggestion of the prudent Sir Robert Hailes, he sent an evasive answer, with a command that the Commons should attend him at Windsor on the Sunday following. That it was a stratagem to gain entrance to the Tower, was the opinion of several, but, after much discussion, it was decided that the man should be admitted, and that the monk should be exhibited merely to intimidate the rebels, until the result of this promised communication should be known. HoMEŮͬÐÔÁµcbcb
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