.. role:: ref(emphasis)

.. _varnish-cli(7):

===========
varnish-cli
===========

------------------------------
Varnish Command Line Interface
------------------------------

:Manual section: 7

DESCRIPTION
===========

Varnish has a command line interface (CLI) which can control and change
most of the operational parameters and the configuration of Varnish,
without interrupting the running service.

The CLI can be used for the following tasks:

configuration
     You can upload, change and delete VCL files from the CLI.

parameters
     You can inspect and change the various parameters Varnish has
     available through the CLI. The individual parameters are
     documented in the varnishd(1) man page.

bans
     Bans are filters that are applied to keep Varnish from serving
     stale content. When you issue a ban Varnish will not serve any
     *banned* object from cache, but rather re-fetch it from its
     backend servers.

process management
     You can stop and start the cache (child) process though the
     CLI. You can also retrieve the latest stack trace if the child
     process has crashed.

If you invoke varnishd(1) with -T, -M or -d the CLI will be
available. In debug mode (-d) the CLI will be in the foreground, with
-T you can connect to it with varnishadm or telnet and with -M
varnishd will connect back to a listening service *pushing* the CLI to
that service. Please see :ref:`varnishd(1)` for details.

.. _ref_syntax:

Syntax
------

The Varnish CLI is similar to another command line interface, the Bourne
Shell. Commands are usually terminated with a newline, and they may take
arguments. The command and its arguments are *tokenized* before parsing,
and as such arguments containing spaces must be enclosed in double quotes.

It means that command parsing of

::

   help banner

is equivalent to

::

   "help" banner

because the double quotes only indicate the boundaries of the ``help``
token.

Within double quotes you can escape characters with \\ (backslash). The \\n,
\\r, and \\t get translated to newlines, carriage returns, an tabs.  Double
quotes and backslashes themselves can be escaped with \\" and \\\\
respectively.

To enter characters in octals use the \\nnn syntax. Hexadecimals can
be entered with the \\xnn syntax.

Commands may not end with a newline when a shell-style *here document*
(here-document or heredoc) is used. The format of a here document is::

   << word
	here document
   word

*word* can be any continuous string chosen to make sure it doesn't appear
naturally in the following *here document*. Traditionally EOF or END is
used.

Quoting pitfalls
----------------

Integrating with the Varnish CLI can be sometimes surprising when quoting
is involved. For instance in Bourne Shell the delimiter used with here
documents may or may not be separated by spaces from the ``<<`` token::

   cat <<EOF
   hello
   world
   EOF
   hello
   world

With the Varnish CLI, the ``<<`` and ``EOF`` tokens must be separated by
at least one blank::

   vcl.inline boot <<EOF
   106 258
   Message from VCC-compiler:
   VCL version declaration missing
   Update your VCL to Version 4 syntax, and add
           vcl 4.0;
   on the first line of the VCL files.
   ('<vcl.inline>' Line 1 Pos 1)
   <<EOF
   ##---

   Running VCC-compiler failed, exited with 2
   VCL compilation failed

With the missing space, the here document can be added and the actual VCL
can be loaded::

   vcl.inline test << EOF
   vcl 4.0;

   backend be {
           .host = "localhost";
   }
   EOF
   200 14
   VCL compiled.

When using a front-end to the Varnish-CLI like ``varnishadm``, one must
take into account the double expansion happening.  First in the shell
launching the ``varnishadm`` command and then in the Varnish CLI itself.
When a command's parameter require spaces, you need to ensure that the
Varnish CLI will see the double quotes::

   varnishadm param.set cc_command '"my alternate cc command"'

   Change will take effect when VCL script is reloaded

Otherwise if you don't quote the quotes, you may get a seemingly unrelated
error message::

   varnishadm param.set cc_command "my alternate cc command"
   Unknown request.
   Type 'help' for more info.
   Too many parameters

   Command failed with error code 105

If you are quoting with a here document, you must wrap it inside a shell
multi-line argument::

   varnishadm vcl.inline test '<< EOF
   vcl 4.0;

   backend be {
           .host = "localhost";
   }
   EOF'
   VCL compiled.

Other pitfalls include variable expansion of the shell invoking ``varnishadm``
but this is not directly related to the Varnish CLI. If you get the quoting
right you should be fine even with complex commands.

JSON
----

A number of commands with informational responses support a ``-j`` parameter
for JSON output, as specified below. The top-level structure of the JSON
response is an array with these first three elements:

* A version number for the JSON format (integer)

* An array of strings that comprise the CLI command just received

* The time at which the response was generated, as a Unix epoch time
  in seconds with millisecond precision (floating point)

The remaining elements of the array form the data that are specific to
the CLI command, and their structure and content depend on the
command.

For example, the response to ``status -j`` just contains a string in
the top-level array indicating the state of the child process
(``"running"``, ``"stopped"`` and so forth)::

  [ 2, ["status", "-j"], 1538031732.632, "running"
  ]

The JSON responses to other commands may have longer lists of
elements, which may have simple data types or form structured objects.

JSON output is only returned if command execution was successful. The
output for an error response is always the same as it would have been
for the command without the ``-j`` parameter.

Commands
--------

.. include:: ../include/cli.rst

Backend Pattern
---------------

A backend pattern can be a backend name or a combination of a VCL name
and backend name in "VCL.backend" format.  If the VCL name is omitted,
the active VCL is assumed.  Partial matching on the backend and VCL
names is supported using shell-style wilcards, e.g. asterisk (*).

Examples::

   backend.list def*
   backend.list b*.def*
   backend.set_health default sick
   backend.set_health def* healthy
   backend.set_health * auto


Ban Expressions
---------------

A ban expression consists of one or more conditions.  A condition
consists of a field, an operator, and an argument.  Conditions can be
ANDed together with "&&".

A field can be any of the variables from VCL, for instance req.url,
req.http.host or obj.http.set-cookie.

Operators are "==" for direct comparison, "~" for a regular
expression match, and ">" or "<" for size comparisons.  Prepending
an operator with "!" negates the expression.

The argument could be a quoted string, a regexp, or an integer.
Integers can have "KB", "MB", "GB" or "TB" appended for size related
fields.


.. _ref_vcl_temperature:

VCL Temperature
---------------

A VCL program goes through several states related to the different
commands: it can be loaded, used, and later discarded. You can load
several VCL programs and switch at any time from one to another. There
is only one active VCL, but the previous active VCL will be maintained
active until all its transactions are over.

Over time, if you often refresh your VCL and keep the previous
versions around, resource consumption will increase, you can't escape
that. However, most of the time you want only one to pay the price only
for the active VCL and keep older VCLs in case you'd need to rollback
to a previous version.

The VCL temperature allows you to minimize the footprint of inactive
VCLs. Once a VCL becomes cold, Varnish will release all the resources
that can be be later reacquired. You can manually set the temperature
of a VCL or let varnish
automatically handle it.


Scripting
---------

If you are going to write a script that talks CLI to varnishd, the
include/cli.h contains the relevant magic numbers.

One particular magic number to know, is that the line with the status
code and length field always is exactly 13 characters long, including
the NL character.

The varnishapi library contains functions to implement the basics of
the CLI protocol, see the `vcli.h` include file.

.. _ref_psk_auth:

Authentication with -S
----------------------

If the -S secret-file is given as argument to varnishd, all network
CLI connections must authenticate, by proving they know the contents
of that file.

The file is read at the time the auth command is issued and the
contents is not cached in varnishd, so it is possible to update the
file on the fly.

Use the unix file permissions to control access to the file.

An authenticated session looks like this::

   critter phk> telnet localhost 1234
   Trying ::1...
   Trying 127.0.0.1...
   Connected to localhost.
   Escape character is '^]'.
   107 59
   ixslvvxrgkjptxmcgnnsdxsvdmvfympg

   Authentication required.

   auth 455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a
   200 279
   -----------------------------
   Varnish Cache CLI 1.0
   -----------------------------
   Linux,4.4.0-1-amd64,x86_64,-jnone,-smalloc,-smalloc,-hcritbit
   varnish-trunk revision dc360a4

   Type 'help' for command list.
   Type 'quit' to close CLI session.
   Type 'start' to launch worker process.

The CLI status of 107 indicates that authentication is necessary. The
first 32 characters of the response text is the challenge
"ixsl...mpg". The challenge is randomly generated for each CLI
connection, and changes each time a 107 is emitted.

The most recently emitted challenge must be used for calculating the
authenticator "455c...c89a".

The authenticator is calculated by applying the SHA256 function to the
following byte sequence:

* Challenge string
* Newline (0x0a) character.
* Contents of the secret file
* Challenge string
* Newline (0x0a) character.

and dumping the resulting digest in lower-case hex.

In the above example, the secret file contained foo\n and thus::

   critter phk> cat > _
   ixslvvxrgkjptxmcgnnsdxsvdmvfympg
   foo
   ixslvvxrgkjptxmcgnnsdxsvdmvfympg
   ^D
   critter phk> hexdump -C _
   00000000  69 78 73 6c 76 76 78 72  67 6b 6a 70 74 78 6d 63  |ixslvvxrgkjptxmc|
   00000010  67 6e 6e 73 64 78 73 76  64 6d 76 66 79 6d 70 67  |gnnsdxsvdmvfympg|
   00000020  0a 66 6f 6f 0a 69 78 73  6c 76 76 78 72 67 6b 6a  |.foo.ixslvvxrgkj|
   00000030  70 74 78 6d 63 67 6e 6e  73 64 78 73 76 64 6d 76  |ptxmcgnnsdxsvdmv|
   00000040  66 79 6d 70 67 0a                                 |fympg.|
   00000046
   critter phk> sha256 _
   SHA256 (_) = 455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a
   critter phk> openssl dgst -sha256 < _
   455ce847f0073c7ab3b1465f74507b75d3dc064c1e7de3b71e00de9092fdc89a

The sourcefile lib/libvarnish/cli_auth.c contains a useful function
which calculates the response, given an open filedescriptor to the
secret file, and the challenge string.

EXAMPLES
========

Load a multi-line VCL using shell-style *here document*::

    vcl.inline example << EOF
    vcl 4.0;

    backend www {
        .host = "127.0.0.1";
        .port = "8080";
    }
    EOF

Ban all requests where req.url exactly matches the string /news::

    ban req.url == "/news"

Ban all documents where the serving host is "example.com" or
"www.example.com", and where the Set-Cookie header received from the
backend contains "USERID=1663"::

    ban req.http.host ~ "^(?i)(www\\.)?example\\.com$" && obj.http.set-cookie ~ "USERID=1663"

AUTHORS
=======

This manual page was originally written by Per Buer and later modified
by Federico G. Schwindt, Dridi Boukelmoune, Lasse Karstensen and
Poul-Henning Kamp.

SEE ALSO
========

* :ref:`varnishadm(1)`
* :ref:`varnishd(1)`
* :ref:`vcl(7)`
