unicorn - a rackup-like command to launch the Unicorn HTTP
server
unicorn [-c CONFIG_FILE] [-E RACK_ENV] [-D] [RACKUP_FILE]
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.
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.
- -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.
- -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).
- -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.
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.
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.
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.
The Unicorn Community <unicorn-public@yhbt.net>.