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

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 discour‐
       aged.

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 di‐
rectives 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 daemo‐
nization to allow more control over the startup/upgrade process. Unless specified in the CON‐
FIG_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 "lis‐
ten" 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-spe‐
cific 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 mul‐
              tiple times on the command-line, only the last-specified value takes effect.  This option only ex‐
              ists  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  com‐
              mand-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 de‐
              limit 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 ex‐
              ecuted 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 (https://yhbt.net/unicorn/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  ex‐
       actly 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 en‐
       couraged 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  "develop‐
       ment",  but  no  other  values  of RACK_ENV.  If needed, they must be individually specified in the RACK‐
       UP_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  envi‐
       ronment  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_lis‐
       ten_fds(3) manpage.  Users relying on this feature do not need to specify a listen socket in the  unicorn
       config file.

AUTHORS

       The Unicorn Community <unicorn-public@yhbt.net>.

Unicorn User Manual                            September 15, 2009                                     UNICORN(1)