1. socketmaster(1)
  2. socketmaster(1)

NAME

socketmaster - Zero downtime restart for your apps

SYNOPSIS

socketmaster [-listen=URI] [-command=PATH] [-start=MILLIS] [-syslog]

DESCRIPTION

socketmaster is a generic solution to the restart problem: you want to restart your app but neither lose any active connection nor refuse new connections.

socketmaster opens the socket you want to listen on and passes it onto your program. Because socketmaster is simple enough it doesn't need to be restarted and can keep your file-descriptor indefinitely open.

-command=PATH

Defines the location of the program to execute and pass the file-descriptor onto. If you need to add arguments to the program, use -- before the command specific arguments or use a wrapper script.

e.g. socketmaster -command command -- -arg1 -arg2

-listen=URI

One of the following schemes are accepted: tcp, tcp4, tcp6 and unix. Example: tcp4://localhost:8945 or unix:///tmp/myapp.sock

-start=MILLIS

Determines how long socketmaster waits before signaling the old process. If MILLIS is set to zero that feature is disabled.

-syslog

Tells socketmaster to log to syslog.

-user=LOGIN

Sets the child process's uid/gid to the given user (looked up in /etc/passwd). This command only works when socketmaster is run as root.

HOW IT WORKS

On start:

On SIGHUP:

Your server is responsible for:

ENVIRONMENT

EINHORN_FDS
This variable is set by socketmaster and passed onto the children. Its value is always 3 and meant for einhorn compatibility.

SIGNALS

On SIGHUP, socketmaster starts a new child process, waits for -start and sends a HUP to the old process.

SIGINT, SIGTERM and SIGQUIT are forwarded to the child processes.

BUGS & CODE

Bug reports and other contributions are welcome! The project's source and issue tracker is located at https://github.com/zimbatm/socketmaster/

socketmaster is Copyright (C) 2012 PandaStream http://pandastream.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

  1. PandaStream
  2. April 2015
  3. socketmaster(1)