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<title>Change log for Varnish 1.1</title>
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<h1>Change log for Varnish 1.1</h1>
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<h2>Changes between 1.0.4 and 1.1</h2>
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<p>Readability of the C source code generated from VCL code
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has been improved.</p>
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<p>Equality (<span class="code">==</span>) and inequality
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(<span class="code">!=</span>) operators have been implemented for IP
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addresses (which previously could only be compared using
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<p>The address of the listening socket on which the client
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connection was received is now available to VCL as the
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<span class="code">server.ip</span> variable.</p>
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<p>Each object's hash key is now computed based on a string
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which is available to VCL as <span class="code">req.hash</span>. A VCL hook
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named <span class="code">vcl_hash</span> has been added to allow VCL scripts
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to control hash generation (for instance, whether or not to
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include the value of the <span class="code">Host:</span> header in the
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<p>The setup code for listening sockets has been modified to
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detect and handle situations where a host name resolves to
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multiple IP addresses. It will now attempt to bind to each IP
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address separately, and report a failure only if none of them
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<p>Network or protocol errors that occur while retrieving an
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object from a backend server now result in a synthetic error
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page being inserted into the cache with a 30-second TTL. This
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should help avoid driving an overburdened backend server into
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the ground by repeatedly requesting the same object.</p>
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<p>The child process will now drop root privileges
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immediately upon startup. The user and group to use are
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specified with the <span class="code">user</span> and <span class="code">group</span>
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run-time parameters, which default to <span class="code">nobody</span> and
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<span class="code">nogroup</span>, respectively. Other changes have been
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made in an effort to increase the isolation between parent and
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child, and reduce the impact of a compromise of the child
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<p>Objects which are received from the backend with a
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<span class="code">Vary:</span> header are now stored separately according to
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the values of the headers specified in <span class="code">Vary:</span>. This
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allows Varnish to correctly cache e.g. compressed and
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uncompressed versions of the same object.</p>
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<p>Each Varnish instance now has a name, which by default is
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the host name of the machine it runs on, but can be any string
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that would be valid as a relative or absolute directory name.
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It is used to construct the name of a directory in which the
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server state as well as all temporary files are stored. This
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makes it possible to run multiple Varnish instances on the same
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machine without conflict.</p>
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<p>When invoked with the <span class="code">-C</span> option,
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<span class="code">varnishd</span> will now not just translate the VCL code
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to C, but also compile the C code and attempt to load the
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resulting shared object.</p>
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<p>Attempts by VCL code to reference a variable outside its
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scope or to assign a value to a read-only variable will now
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result in compile-time rather than run-time errors.</p>
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<p>The new command-line option <span class="code">-F</span> will make
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<span class="code">varnishd</span> run in the foreground, without enabling
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<p>New VCL variables have been introduced to allow inspection
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and manipulation of the request sent to the backend
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(<span class="code">bereq.request</span>, <span class="code">bereq.url</span>,
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<span class="code">bereq.proto</span> and <span class="code">bereq.http</span>) and the
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response to the client (<span class="code">resp.proto</span>,
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<span class="code">resp.status</span>, <span class="code">resp.response</span> and
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<span class="code">resp.http</span>).</p>
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<p>Statistics from the storage code (including the amount of
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data and free space in the cache) are now available to
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<span class="code">varnishstat</span> and other statistics-gathering
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<p>Objects are now kept on an LRU list which is kept loosely
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up-to-date (to within a few seconds). When cache runs out, the
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objects at the tail end of the LRU list are discarded one by one
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until there is enough space for the freshly requested object(s).
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A VCL hook, <span class="code">vcl_discard</span>, is allowed to inspect each
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object and determine its fate by returning either
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<span class="code">keep</span> or <span class="code">discard</span>.</p>
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<p>A new VCL hook, <span class="code">vcl_deliver</span>, provides a
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chance to adjust the response before it is sent to the
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<p>A new management command, <span class="code">vcl.show</span>, displays
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the VCL source code of any loaded configuration.</p>
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<p>A new VCL variable, <span class="code">now</span>, provides VCL scripts
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with the current time in seconds since the epoch.</p>
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<p>A new VCL variable, <span class="code">obj.lastuse</span>, reflects the
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time in seconds since the object in question was last
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<p>VCL scripts can now add an HTTP header (or modify the
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value of an existing one) by assigning a value to the
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corresponding variable, and strip an HTTP header by using the
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<span class="code">remove</span> keyword.</p>
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<p>VCL scripts can now modify the HTTP status code of cached
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objects (<span class="code">obj.status</span>) and responses
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(<span class="code">resp.status</span>)</p>
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<p>Numeric and other non-textual variables in VCL can now be
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assigned to textual variables; they will be converted as
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<p>VCL scripts can now apply regular expression substitutions
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to textual variables using the <span class="code">regsub</span>
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<p>A new management command, <span class="code">status</span>, returns the
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state of the child.</p>
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<p>Varnish will now build and run on Mac OS X.</p>
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<p>This is a new utility which sends a single command to a
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Varnish server's management port and prints the result to
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<span class="code">stdout</span>, greatly simplifying the use of the
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management port from scripts.</p>
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<p>The user interface has been greatly improved; the
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histogram will be automatically rescaled and redrawn when the
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window size changes, and it is updated regularly rather than at
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a rate dependent on the amount of log data gathered. In
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addition, the name of the Varnish instance being watched is
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displayed in the upper right corner.</p>
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<p>In addition to client traffic, <span class="code">varnishncsa</span>
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can now also process log data from backend traffic.</p>
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<p>A bug that would cause <span class="code">varnishncsa</span> to
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segfault when it encountered an empty HTTP header in the log
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file has been fixed.</p>
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<h3>varnishreplay</h3>
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<p>This new utility will attempt to recreate the HTTP traffic
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which resulted in the raw Varnish log data which it is
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<p>Don't print lifetime averages when it doesn't make any
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sense—for instance, there is no point in dividing the
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amount in bytes of free cache space by the lifetime in seconds
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of the <span class="code">varnishd</span> process.</p>
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<p>The user interface has been greatly improved;
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<span class="code">varnishstat</span> will no longer print more than fits in
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the terminal, and will respond correctly to window resize
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events. The output produced in one-shot mode has been modified
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to include symbolic names for each entry. In addition, the name
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of the Varnish instance being watched is displayed in the upper
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right corner in curses mode.</p>
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<p>The user interface has been greatly improved;
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<span class="code">varnishtop</span> will now respond correctly to window
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resize events, and one-shot mode (<span class="code">-1</span>) actually
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works. In addition, the name of the Varnish instance being
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watched is displayed in the upper right corner in curses
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doc/changes-1.1.html
