I have a process which I am monitoring using Monit. If process dies for some reason, I want to send a Slack notification using a shell script and also restart it. This behaviour though does not work with "does not exist" directive. The last one is executed and previous one ignored. For example code below:
check process xyz with pidfile /var/run/xyz.pid
start program = "/etc/init.d/xyz start" with timeout 60 seconds
stop program = "/etc/init.d/xyz stop"
if does not exist then restart
if does not exist then exec "/opt/somescript.sh"
It executes script but does not restart. it also looks like from documentation that this is how it will behave. Any other way to get this working. Documentation reference (Not exactly clear but resembles the actual behaviour):
If not defined, it defaults to a restart action.
You can override the default action with the following statement:
I believe monit doesn't allow you to have the same statements twice. You would have to write your script on restarting the process in your somescript.sh.
My guess is the default action is already to restart the process, as per the documentation, and you are overriding that with an exec action
Cleaner way is to add the restart script inside your somescript.sh.
If you don't want to do that, you can also combine the two actions in one, like this:
if does not exist then exec "/etc/init.d/xyz restart && /opt/somescript.sh"
Related
I want to execute a cron after creation of some entity every 2 minutes and I should be able to stop it through code only. Is it possible ?
For the simplest way that I can think of right now that you can do what #tlehman said and add a "checking flag" in the code. (maybe just a simple variable inside a filename)
so before the cron started, it should check for a file with X variable with value true/false.
if true then it should run the code, if false then exit.
(you could then write another code to modify that "check file" to enable/disable the cron)
That sounds like a job for the whenever gem, you can use it's simple DSL like so:
every 2.minutes do
runner "SomeRubyCommand.do_work"
end
I'm very new to rails and I have a script that I run from the console like this
$ ruby axml2xml.rb ExamPaper.apk
Now, how do I call this script from within my controller method and pass the same parameter as ExamPaper.apk?
I tried require 'axml2xml.rb' but got some error pointing to this line of code Zip::ZipFile.foreach(ARGV[0]) do |f|. So basically, how do I make something like axml2xml.rb 'ExamPaper.apk' in my controller?
You have at least 3 options:
exec(command)
%x{ command }
system(command)
They have different behaviors, so make sure to read this quicktip and/or the answer of this question to learn more about these commands.
In your case, the backticks or %x command is probably the best option.
value = `ruby axml2xml.rb ExamPaper.apk`
You can try using system or popen, but only for short tasks, for more information about that, please see here.
If your task is more time consuming you definitely should have a look at something like delayed_job and use a background job or some sort of queue to run your job. This way your server doesn't get blocked and your users do not have to wait til your job completes.
If you want to execute it as a shell command, use:
exec 'ruby axml2xml.rb ExamPaper.apk'
In ruby there are several ways to run shell commands.
system("ls")
%x("ls")
`ls` #nice they are back ticks
exec "ls"
But I'm not sure about the permissions necessary for running commands like that via rails.
User goes to page A to create a new multiplayer game
The script in page A generates a unique ID for the game, and creates a worker for it. Something like: rails runner GameWorker.new(:game_id => game_id).start_game
The script in page A redirects the user to page B, where he can see the newly created game, and others can join.
The worker should be alive until the end of the game.
What would be the proper way to run the command that starts the worker? It must be non blocking and ideally redirect output to the log file, in case something goes wrong.
I'm using Rails 3, if it matters.
UPDATE
I'm gonna rephrase my question: How to run a linux command from within ruby and don't wait for the command to end? I mean the equivalent for &>>. In php for instance, &>> works fine and I don't need to use any special php functiont, but in ruby it seems to get overriden by and the script waits for the command to end and grab the output.
I HIGHLY recommend not running a process per game. If you want a non-blocking game that is not turn based, then you probably want to look at event-machine, or something like https://github.com/celluloid/celluloid-io
With either, you'll be creating threads that you'll process at future points in time.
But -- if you do want to just fire off a process in ruby, here you go.. from How to fire and forget a subprocess?
pid = Process.fork
if pid.nil? then
# In child
exec "whatever --take-very-long"
else
# In parent
Process.detach(pid)
end
I have a rails 3 application and looked around in the internet for daemons but didnt found the right for me..
I want a daemon which fetches data permanently (exchange courses) from a web resource and saves it to the database..
like:
while true
Model.update_attribte(:course, http::get.new("asdasd").response)
end
I've only seen cron like jobs, but they only run after a specific time... I want it permanently, depending on how long it takes to end the query...
Do you understand what i mean?
The gem light-daemon I wrote should work very well in your case.
http://rubygems.org/gems/light-daemon
You can write your code in a class which has a perform method, use a queue system like this and at application startup enqueue the job with Resque.enqueue(Updater).
Obviously the job won't end until the application is stopped, personally I don't like that, but if this is the requirement.
For this reason if you need to execute other tasks you should configure more than one worker process and optionally more than one queue.
If you can edit your requirements and find a trigger for the update mechanism the same approach still works, you only have to remove the while true loop
Sample class needed:
Class Updater
#queue = :endless_queue
def self.perform
while true
Model.update_attribute(:course, http::get.new("asdasd").response)
end
end
end
Finaly i found a cool solution for my problem:
I use the god gem -> http://god.rubyforge.org/
with a bash script (link) for starting / stopping a simple rake task (with an infinite loop in it).
Now it works fine and i have even some monitoring with god running that ensures that the rake task runs ok.
I'm having trouble debugging cucumber steps due to unique conditions of the testing environment. I wish there was a step that could pause a selenium test and let me take over.
E.g.
Scenario: I want to take over here
Given: A bunch of steps have already run
When: I'm stuck on an error
Then: I want to take control of the mouse
At that point I could interact with the application exactly as if I had done all the previous steps myself after running rails server -e test
Does such a step exist, or is there a way to make it happen?
You can integrate ruby-debug into your Cucumber tests. Nathaniel Ritmeyer has directions here and here which worked for me. You essentially require ruby-debug, start the debugger in your environment file, and then put "breakpoint" where ever you want to see what's going on. You can both interact with the browser/application and see the values of your ruby variables in the test. (I'm not sure whether it'll let you see the variables in your rails application itself - I'm not testing against a rails app to check that).
I came up with the idea to dump the database. It doesn't let you continue work from the same page, but if you have the app running during the test, you can immediately act on the current state of things in another browser (not the one controlled by Selenium).
Here is the step:
When /I want to take control/i do
exec "mysqldump -u root --password=* test > #{Rails.root}/support/snapshot.sql"
end
Because it is called by exec, DatabaseCleaner has no chance to truncate tables, so actually it's irrelevant that the command is a database dump. You don't have to import the sql to use the app in its current state, but it's there if you need it.
My teammate has done this using selenium, firebug a hook (#selenium_with_firebug)
Everything he learned came from this blogpost:
http://www.allenwei.cn/tips-add-firebug-extension-to-capybara/
Add the step
And show me the page
Where you want to interact with it
Scenario: I want to take over here
Given: A bunch of steps have already run
When: I'm stuck on an error
Then show me the page
use http://www.natontesting.com/2009/11/09/debugging-cucumber-tests-with-ruby-debug/
Big thank you to #Reed G. Law for the idea of dumping the database. Then loading it into development allowed me to determine exactly why my cucumber feature was not impacting database state as I had expected. Here's my minor tweak to his suggestion:
When /Dump the database/i do
`MYSQL_PWD=password mysqldump -u root my_test > #{Rails.root}/snapshot.sql`
# To replicate state in development run:
# `MYSQL_PWD=password mysql -u root my_development < snapshot.sql`
end
You can also use the following in feature/support/debugging.rb to let you step through the feature one step at a time:
# `STEP=1 cucumber` to pause after each step
AfterStep do |scenario|
next unless ENV['STEP']
unless defined?(#counter)
puts "Stepping through #{scenario.title}"
#counter = 0
end
#counter += 1
print "At step ##{#counter} of #{scenario.steps.count}. Press Return to"\
' execute...'
STDIN.getc
end