% UNICORN(1) Unicorn User Manual
% The Unicorn Community <unicorn-public@bogomips.org>
% September 15, 2009

# NAME

unicorn - a rackup-like command to launch the Unicorn HTTP server

# SYNOPSIS

unicorn [-c CONFIG_FILE] [-E RACK_ENV] [-D] [RACKUP_FILE]

# DESCRIPTION

A rackup(1)-like command to launch Rack applications using Unicorn.
It is expected to be started in your application root (APP_ROOT),
but the "working_directory" directive may be used in the CONFIG_FILE.

While unicorn takes a myriad of command-line options for
compatibility with ruby(1) and rackup(1), it is recommended to stick
to the few command-line options specified in the SYNOPSIS and use
the CONFIG_FILE as much as possible.

# RACKUP FILE

This defaults to \"config.ru\" in APP_ROOT.  It should be the same
file used by rackup(1) and other Rack launchers, it uses the
*Rack::Builder* DSL.

Embedded command-line options are mostly parsed for compatibility
with rackup(1) but strongly discouraged.

# UNICORN OPTIONS
-c, \--config-file CONFIG_FILE
:   Path to the Unicorn-specific config file.  The config file is
    implemented as a Ruby DSL, so Ruby code may executed.
    See the RDoc/ri for the *Unicorn::Configurator* class for the full
    list of directives available from the DSL.
    Using an absolute path for for CONFIG_FILE is recommended as it
    makes multiple instances of Unicorn easily distinguishable when
    viewing ps(1) output.

-D, \--daemonize
:   Run daemonized in the background.  The process is detached from
    the controlling terminal and stdin is redirected to "/dev/null".
    Unlike many common UNIX daemons, we do not chdir to \"/\"
    upon daemonization to allow more control over the startup/upgrade
    process.
    Unless specified in the CONFIG_FILE, stderr and stdout will
    also be redirected to "/dev/null".

-E, \--env RACK_ENV
:   Run under the given RACK_ENV.  See the RACK ENVIRONMENT section
    for more details.

-l, \--listen ADDRESS
:   Listens on a given ADDRESS.  ADDRESS may be in the form of
    HOST:PORT or PATH, HOST:PORT is taken to mean a TCP socket
    and PATH is meant to be a path to a UNIX domain socket.
    Defaults to "0.0.0.0:8080" (all addresses on TCP port 8080)
    For production deployments, specifying the "listen" directive in
    CONFIG_FILE is recommended as it allows fine-tuning of socket
    options.
-N, \--no-default-middleware
:   Disables loading middleware implied by RACK_ENV.  This bypasses the
    configuration documented in the RACK ENVIRONMENT section, but still
    allows RACK_ENV to be used for application/framework-specific purposes.

# RACKUP COMPATIBILITY OPTIONS
-o, \--host HOST
:   Listen on a TCP socket belonging to HOST, default is
    "0.0.0.0" (all addresses).
    If specified multiple times on the command-line, only the
    last-specified value takes effect.
    This option only exists for compatibility with the rackup(1) command,
    use of "-l"/"\--listen" switch is recommended instead.

-p, \--port PORT
:   Listen on the specified TCP PORT, default is 8080.
    If specified multiple times on the command-line, only the last-specified
    value takes effect.
    This option only exists for compatibility with the rackup(1) command,
    use of "-l"/"\--listen" switch is recommended instead.

-s, \--server SERVER
:   No-op, this exists only for compatibility with rackup(1).

# RUBY OPTIONS
-e, \--eval LINE
:   Evaluate a LINE of Ruby code.  This evaluation happens
    immediately as the command-line is being parsed.

-d, \--debug
:   Turn on debug mode, the $DEBUG variable is set to true.

-w, \--warn
:   Turn on verbose warnings, the $VERBOSE variable is set to true.

-I, \--include PATH
:   specify $LOAD_PATH.  PATH will be prepended to $LOAD_PATH.
    The \':\' character may be used to delimit multiple directories.
    This directive may be used more than once.  Modifications to
    $LOAD_PATH take place immediately and in the order they were
    specified on the command-line.

-r, \--require LIBRARY
:   require a specified LIBRARY before executing the application.  The
    \"require\" statement will be executed immediately and in the order
    they were specified on the command-line.

# SIGNALS

The following UNIX signals may be sent to the master process:

* HUP - reload config file, app, and gracefully restart all workers
* INT/TERM - quick shutdown, kills all workers immediately
* QUIT - graceful shutdown, waits for workers to finish their
  current request before finishing.
* USR1 - reopen all logs owned by the master and all workers
  See Unicorn::Util.reopen_logs for what is considered a log.
* USR2 - reexecute the running binary.  A separate QUIT
  should be sent to the original process once the child is verified to
  be up and running.
* WINCH - gracefully stops workers but keep the master running.
  This will only work for daemonized processes.
* TTIN - increment the number of worker processes by one
* TTOU - decrement the number of worker processes by one

See the [SIGNALS][4] document for full description of all signals
used by Unicorn.

#  RACK ENVIRONMENT

Accepted values of RACK_ENV and the middleware they automatically load
(outside of RACKUP_FILE) are exactly as those in rackup(1):

* development - loads Rack::CommonLogger, Rack::ShowExceptions, and
                Rack::Lint middleware
* deployment  - loads Rack::CommonLogger middleware
* none        - loads no middleware at all, relying
                entirely on RACKUP_FILE

All unrecognized values for RACK_ENV are assumed to be
"none".  Production deployments are strongly encouraged to use
"deployment" or "none" for maximum performance.

As of Unicorn 0.94.0, RACK_ENV is exported as a process-wide environment
variable as well.  While not current a part of the Rack specification as
of Rack 1.0.1, this has become a de facto standard in the Rack world.

Note the Rack::ContentLength and Rack::Chunked middlewares are also
loaded by "deployment" and "development", but no other values of
RACK_ENV.  If needed, they must be individually specified in the
RACKUP_FILE, some frameworks do not require them.

# ENVIRONMENT VARIABLES

The RACK_ENV variable is set by the aforementioned \-E switch.
All application or library-specific environment variables (e.g. TMPDIR)
may always be set in the Unicorn CONFIG_FILE in addition to the spawning
shell.  When transparently upgrading Unicorn, all environment variables
set in the old master process are inherited by the new master process.
Unicorn only uses (and will overwrite) the UNICORN_FD environment
variable internally when doing transparent upgrades.

UNICORN_FD is a comma-delimited list of one or more file descriptors
used to implement USR2 upgrades.  Init systems may bind listen sockets
itself and spawn unicorn with UNICORN_FD set to the file descriptor
numbers of the listen socket(s).

As of unicorn 5.0, LISTEN_PID and LISTEN_FDS are used for socket
activation as documented in the sd_listen_fds(3) manpage.  Users
relying on this feature do not need to specify a listen socket in
the unicorn config file.

# SEE ALSO

* *Rack::Builder* ri/RDoc
* *Unicorn::Configurator* ri/RDoc
* [Unicorn RDoc][1]
* [Rack RDoc][2]
* [Rackup HowTo][3]

[1]: https://bogomips.org/unicorn/
[2]: https://www.rubydoc.info/github/rack/rack/
[3]: https://github.com/rack/rack/wiki/tutorial-rackup-howto
[4]: https://bogomips.org/unicorn/SIGNALS.html
