First of all I must admit that been a Ruby developer for some time now I
still find *GOD *hard to configure and hard to understand not sure of exact
reason of this (Lack of documentation or lack of understanding from my part
)but still fact is even today I'm facing this, perhaps this post might help
me find those answer as well
Here are my Problems
*Problem no 1 ( PID dilemma ) : *
Firstly here how my GOD configuration* simple.god* look like
DIRECTORY = "/Users/joshianiket22/myProject/god_script"God.pid_file_directory =
DIRECTORYGod.watch do |w|
w.name = "mess"
w.start = "ruby /Users/joshianiket22/myProject/god_script/simple.rb"
w.pid_file = File.join(DIRECTORY,'simple.pid')
puts File.join(DIRECTORY,'simple.pid')
w.stop = "ruby -e 'puts \"#{DateTime.now}\"'"
w.log = File.join(DIRECTORY,'god.log')
w.behavior(:clean_pid_file)
w.interval = 10.seconds
w.start_if do |start|
start.condition(:process_running) do |c|
puts "Inside start condition"
c.interval = 5.seconds
c.running = false
end
endend
Now God Documentation states
<https://lh5.googleusercontent.com/-nhoBajKdV3I/Uh2vK-m8uaI/AAAAAAAAA_g/VH0bMJ855_c/s1600/download+%282%29.png>
Now if you see my *GOD *configuration file I have specified the *
pid_file_directory*
DIRECTORY = "/Users/joshianiket22/myProject/god_script"God.pid_file_directory =
DIRECTORY
yet no *PID *(neither of GOD Server nor for the process monitored by GOD is
stored in that directory) is ever stored in that directory
In fact I have also mention this in my* GOD* configuration
w.pid_file = File.join(DIRECTORY,'simple.pid')
but still the same result no *PID *(not even for the *simple.rb* )
BTW, I have started *GOD *
*
*
sudo god -c simple.god
one reason could be that *PID *directory is not writable by GOD ,but to
tackle that I did *chmod* , *chown* in fact start God using* sudo *
still no luck
Can anyone explain that now
FYI , the Log file work btw
*Problem 2 (Confusion over start_if conditions) *
According to GOD documentation
<https://lh6.googleusercontent.com/-qFE_V7nOzlg/Uh2ypLb8H5I/AAAAAAAAA_s/y0iNl-onPio/s1600/start_if.png>
Now I get (not exactly) it something like a condition called start only if
specified condition is met but I don't understand is what is*:process_running
*
is this predefined condition that implies that check for whether a
processing is running or not If yes what other set of conditions are
available
Also what very hard to understand is when would the do block part will be
executed when *start.condition(:process_running) *return* false or true*because
I trying to understand the initialization under
*do* block
I understand the first part it set the* interval to 5 seconds* to look to
start as oppose to global interval but what does the c.*running = false *
Now where does this attributes is used and also what are *other list of
attributes* that we can look for extend the block
Anyway I think the attributes is used to perform a check something like
this
loop(!running)
## run start condition until the running is set to true which would happen as
soon process start running
sleep interval ## 5 seconds intervalend
Please feel free to correct me if I'm wrong on this and also please answer
what are* other list of attributes* *and condition(like :process_running) *that
we/I can use to extend the block check for *start_if*
FYI, If I remove the start_if my *simple.rb *does not get start at all
which is weird to me (is this *normal* as well)
*Problem 3 : Command dilemma (start/stop/restart)*
Given that you looked at my above configuration script if have a *start
command written *something like this
w.start = "ruby /Users/joshianiket22/myProject/god_script/simple.rb"
Now I understand the *start* bit , but is it required to *write/define* the
stop , restart command as well on our configuration file
I assuming Its not ,but you can defined your own *stop, restart* command,
but if you don't define yours own GOD would take care by defining it own
stop and restart command (which mean stop the process started by start
command and other stuff , would be taken care off the hook by GOD are my
assumptions right.)
Anyways based on my above assumption , when I run this on my command line
sudo god stop mess
I get this
Sending 'stop' command
The following watches were affected:
mess
but I don't see my *simple.rb *processing getting stopped .
This one of the biggest issue I have seen thus far ,because I have seen
many GOD configuration file which have* start *command written in them but
not *stop* and *restart* command
Also , I have another GOD configuration for
resque<https://github.com/resque/resque> which
look like this (*Note* I not using the resque provided GOD configuration
under example directory)
APPLICATION_ROOT = '/var/apps/integration/adminapp'RAILS_ENV =
'integration'God.watch do |w|
w.env = {
'PATH' =>
"/home/deployer/.rbenv/bin:/home/deployer/.rbenv/shims:#{ENV['PATH']}",
'USER' => 'deployer',
'HOME' => '/home/deployer',
'QUEUE'=> '*',
'TERM_CHILD' => '1',
'RAILS_ENV' => RAILS_ENV || "production",
'PIDFILE' => "#{APPLICATION_ROOT}/shared/pids/resque.pid"
}
w.uid = 'deployer'
w.gid = 'deployer'
w.name = "resque"
w.interval = 30.seconds
w.start = "/bin/bash -c 'cd #{APPLICATION_ROOT}/current && .
/home/deployer/.secrets && /usr/bin/env bundle exec \"RAILS_ENV=#{RAILS_ENV}
QUEUE=* rake environment resque:work\" '"
w.log = "#{APPLICATION_ROOT}/shared/log/god_resque.log"
w.start_grace = 30.seconds
w.pid_file = "#{APPLICATION_ROOT}/shared/pids/god_minerva.pid"
w.behavior(:clean_pid_file)
w.restart_if do |restart|
restart.condition(:cpu_usage) do |c|
c.above = 50.percent
c.times = 5
end
end
# determine the state on startup
w.transition(:init, { true => :up, false => :start }) do |on|
on.condition(:process_running) do |c|
c.running = true
end
end
# determine when process has finished starting
w.transition([:start, :restart], :up) do |on|
on.condition(:process_running) do |c|
c.running = true
c.interval = 5.seconds
end
# failsafe
on.condition(:tries) do |c|
c.times = 5
c.transition = :start
c.interval = 5.seconds
end
end
# start if process is not running
w.transition(:up, :start) do |on|
on.condition(:process_running) do |c|
c.running = false
end
endend
FYI , again over here the PID is not stored but, that altogether a
different question that I have address earlier and GOD is started using *
sudo* command
now you can see that I have *start * command that look like this
w.start = "/bin/bash -c 'cd #{APPLICATION_ROOT}/current && .
/home/deployer/.secrets && /usr/bin/env bundle exec \"RAILS_ENV=#{RAILS_ENV}
QUEUE=* rake environment resque:work\" '"
I don't have *stop* , or *restart* command
*
*
Now in my deploy (VLAD <https://github.com/seattlerb/vlad>) script I have a
piece of code that look like this (where I send the restart task to God for
resque) or basically when I do this
sudo god restart resque
sudo god stop resque
It doesn't do anything and I still see the resque worker running with same*PID
*
*
*
Can Anyone explain whether or not it is required to define command (like
stop/restart ) inside GOD configuration file ?
*
*
*Problem 4 (Whether or whether not to put process in background )*
I'll be more specify is this , ideally if I have to put resque worker in
background (without GOD) I would run command the following command
RAILS_ENV=integration QUEUE=* BACKGROUND=yes PID_FILE=resque.pid bundle exec
rake resque:work
* BACKROUND=yes *is the key over here
Now I know and according to GOD documentation which states
<https://lh3.googleusercontent.com/-TDlSehfpU-0/Uh3B6-L6-LI/AAAAAAAAA_8/L5QyePNwIis/s1600/download+%283%29.png>
So the question over here whether should I *DAEMONize* my process
irrespective it run under GOD (which effectively *DAEMONize* at some point)
or I should *not DAEMONize* it
and let GOD do it .
And Let assume If I *DAEMONize *my process will GOD still keep track of the
process (like GOD act on restart or stop command for resque which is
DAEMONize by me)
to be more precise if I change my *start* command to look like this
w.start = "/bin/bash -c 'cd #{APPLICATION_ROOT}/current && .
/home/deployer/.secrets && /usr/bin/env bundle exec \"RAILS_ENV=#{RAILS_ENV}
BACKGROUND=yes QUEUE=* rake environment resque:work\" '"
will GOD still keep track of the above resque process and will it respond
to *stop/restart/start* command after doing so
like
sudo god restart resque
sudo god stop resque
sudo god start resque
Help me out guys in better understanding the GOD monitoring in whole
Hope I made the everything easy for you guys to understand
Thanks
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