Some words

It’s been very busy these days, I was very busy doing my projects, and use my spare time create a proxy tool for Cocoa, called iProxy.

iProxy is a smart SSH tunnel proxy that can using SSH tunnel to bypass the firewall and using the PAC to choose which url should go through the proxy, and it can also choose free http proxy too.

I haven’t release it yet, since I’m coding for the smart PAC part and try to figure out how to charge for that, of course, the iProxy client is open source too.

That’s the reason that I haven’t update this blog for a very long time(about 2 months), after the launch of iProxy, I maybe have time to sit down and write something about the Objective-C and cocoa programming, and for now, I just need to perfect iProxy and make it more like a product, not a toy.

This is the additional words for this blog, this blog is going to announce the scripting tool I told before at my last blog.

This script tool, I called it lancelot. The details, is as below. You can find the code of lancelot at here: https://github.com/guitarpoet/lancelot

Wish you will like it, and try for it, at least, I’m enjoying using it in my projects now.

Lacenlot, tool for manage multiple daemon processes

Introduction & Purpose

The purpose for lancelot is to help to launch and mange the worker processes for
my working project.

Lancelot is used to solve the problem I encountered in my project:

1. I need to launch many worker processes as daemon process on many slave \
   machines (say, 5 worker for each slave machine)
2. After some configuration change, I need to restart all the worker processes \
   (sure, you can use apache zookeeper to handle this, but it will make the \
   worker process more complex, since the worker process just need to do some \
   very simple work (get the data from an url and store it into hdfs for example)
3. I need to check for all the worker process’s status at a period of time \
   (or maybe I want to get an alert when 50% of the processes is down)

So, lancelot is used for:

1. Launching as many worker processes as you want, and save the pid files as the \
   template you have gave it (something like /var/run/worker-1.pid), and the \
   redirect the standard output, error output to the templates you have gave it \
   (somthing like /var/log/worker-1.log /var/log/worker-1.err)
2. Launching the worker processes as daemon using nohup or daemonize, lancelot \
   prefer daemonize than nohup, anyway, the worker process won’t exit until it \
   gets an error or itself should exit
3. Check the status of all the worker process you have launched, using a ps \
   format, you can also set the ps format, you can use grep pattern or pid \
   template to check for the status
4. Kill all the processes you want to kill by using a pid template or the pattern

And, for the ease to deploy lancelot to multiple slave machines, lancelot also has
a deploy function to deploy it to all the machines, this function is depend on
another script tool called taktuk.

Installation

For the installation, just unpack the package and copy lancelot to the destination
you want to put it to(/usr/local/lancelot for default).

And change the lancelot home variable in the lancelot script. Then add or ln lancelot
script to the PATH (usually /usr/local/bin/lancelot)

And you can use it.

Usage

You can use lancelot script like this

Lancelot command options

For example:
lancelot launch -c ~/launch_config -t 10 /bin/sh fetch_data.sh

Lancelot Launch

Description:     
    The process launching script.    
    Example:    launch -o /tmp/a-{}.log -e /tmp/a-{}.err -w /tmp /bin/ls .
    Email to guitarpoet@gmail.com if bug found.
Options:     
    -w|--workingdir:        The working dir for the launch
        This option requires 1 args.
    -o|--output:
        The standard output of the application
        This option requires 1 args.
    -e|--error:
        The error output of the appliaction
        This option requires 1 args.
    -p|--pid:
        The pid template for the application
        This option requires 1 args.
        Option is required.
    -c|--config:
        The configuration file location for lancelot launch
        This option requires 1 args.
    -t|--count:
        The process count that want lancelot to launch
        This option requires 1 args.

Lancelot Status

Description: 
    The process status script.
    Example:
    status -p /tmp/a-{}.pid
    Email to guitarpoet@gmail.com if bugs found.
Options: 
    -p|--pid:
        The pid template for the application
        This option requires 1 args.
        Option is required.
    -a|--application:
        The application pattern to grep
        This option requires 1 args.
    -c|--config:
        The configuration file location for lancelot launch
        This option requires 1 args.
    -f|--format:
        The ps format for this application, 'pid args' is by default
        This option requires 1 args.

Lancelot Kill

Description: 
    The process kill script.
    Example:
    kill -p /tmp/a-{}.pid
    Email to guitarpoet@gmail.com if bugs found.
Options: 
    -p|--pid:
        The pid template for the application
        This option requires 1 args.
        Option is required.
    -a|--application:
        The application pattern to grep
        This option requires 1 args.
    -c|--config:
        The configuration file location for lancelot launch
        This option requires 1 args.

Lancelot Broadcast

Description: 
    Broadcast exec the lancelot command to all the hosts
    Example:
    broadcast -h ~/hosts status -p /tmp/a-{}.pid
    Email to guitarpoet@gmail.com if bugs found.
Options: 
    -c|--config:
        The configuration file location for lancelot broadcast
        This option requires 1 args.
    -h|--hosts:
        The hosts that should launch the lancelot broadcast
        This option requires 1 args.
    -l|--login:
        The login name for login using taktuk
        This option requires 1 args.