unicorn - Online in the Cloud

PROGRAM:

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 (http://unicorn.bogomips.org/SIGNALS.html) 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). The unicorn
CONFIG_FILE must still have the inherited listen socket parameters defined as in a normal
startup, otherwise the socket will be closed.

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