restarter

Restarter - start-stop-daemon for multiple processes

Restarter is a simple tool to manage processs similar to forever or unix's start-stop-daemon. You can cause a process to restart simply by touching a file, or prevent a process from dying by setting the keep_alive flag. Each process' console output is appended to a log file of your choosing. There are several tools out there like this, but I couldn't find one that managed a list of processes from a single configuration so I wrote my own. We use this tool to restart standalone processes during our capistrano deployment scripts.

Quick Example:

Make a config called "restarter.conf" file that looks like this:

{
  "global_log_file": "/tmp/restarter_output.log",
  "keep_alive": true,
  "restartables":
    [
      {
        "command": "node /tmp/test.js",
        "pid_file": "/tmp/test.pid",
        "signal": "SIGINT",
        "log_file": "/tmp/test.log",
        "watch_file": "/tmp/test.restarter"
      },
      {
        "command": "node /tmp/test2.js",
        "pid_file": "/tmp/test2.pid",
        "signal": "SIGINT",
        "log_file": "/tmp/test2.log",
        "watch_file": "/tmp/test2.restarter"
      }
    ]
}

Then run it like this:

restarter restarter.conf

If keep_alive is set to "true", it will rerun the command if the process pid is missing. You can "touch" the watch_file and restarter will kill the current process and rerun the command to restart it. If you omit the global_log_file parameter, it will send stdout to the console.

The output in the global_log_file will look something like this:

Thu Jan 27 2011 18:01:00 GMT-0800 (PST) : could not find pid to kill: 4918
Thu Jan 27 2011 18:01:00 GMT-0800 (PST) : spawn pid: 4981 from command: node /tmp/test.js
Thu Jan 27 2011 18:01:00 GMT-0800 (PST) : could not find pid to kill: 4919
Thu Jan 27 2011 18:01:00 GMT-0800 (PST) : spawn pid: 4982 from command: node /tmp/test2.js
Thu Jan 27 2011 18:07:44 GMT-0800 (PST) : keep alive command died, pid: 4982 for command: node /tmp/test2.js
Thu Jan 27 2011 18:07:44 GMT-0800 (PST) : rerunning command: node /tmp/test2.js
Thu Jan 27 2011 18:07:44 GMT-0800 (PST) : could not find pid to kill: 4982
Thu Jan 27 2011 18:07:44 GMT-0800 (PST) : spawn pid: 5967 from command: node /tmp/test2.js
Thu Jan 27 2011 18:08:01 GMT-0800 (PST) : watch file updated for command: node /tmp/test2.js
Thu Jan 27 2011 18:08:01 GMT-0800 (PST) : killed: 5967
Thu Jan 27 2011 18:08:01 GMT-0800 (PST) : spawn pid: 6013 from command: node /tmp/test2.js