I'm fairly new to Bash, redis and linux in general and I'm having trouble with creating a script. This is also my first question, I hope it is not a duplicate.
So here's the problem, I'm creating a simple application in ruby for educational purposes, but the feature I'm trying to implement uses redis and sidekiq. What I want to do is to create an executable script (I named it server) that initiates the redis server, initiates the redis, but it should also shutdown redis after the user finalizes the sidekiq.
This is what I came up with:
#!/usr/bin/env sh
set -e
redis-server --daemonize yes
bundle exec sidekiq -r ./a/sample/path/worker.rb
redis-cli shutdown # this is not working, I want to execute this after shutting sidekiq down...
When I run the fourth line, it starts the little Sidekiq "welcome page" and I can't to anything until I shut it down with Control + C. I assumed that after shutting it with this command, it would continue with the script I wrote, which would be the redis-cli shutdown command.
But it does not. When I Control + C the sidekiq, it simply goes back to the command line.
Is there anyone familiar with these concepts that could help me? I wanted a script that would also shutdown redis after I'm done with sidekiq.
Thanks!
Have you considered using Foreman?
http://blog.daviddollar.org/2011/05/06/introducing-foreman.html
https://github.com/ddollar/foreman
Related
I am configuring an app at work which is on a Amazon Web Server.
To get the app running you have to run a shell called "Start.sh"
I want this to be done automatically after booting up the server
I have already tried with the following bash in the User Data section (Which runs on boot)
#!/bin/bash
cd "/home/ec2-user/app_name/"
sh Start.sh
echo "worked" > worked.txt
Thanks for the help
Scripts provided through User Data are only executed the first time the instance is started. (Officially, it is executed once per instance id.) This is done because the normal use-case is to install software, which should only be done once.
If you wish something to run on every boot, you could probably use the cloud-init once-per-boot feature:
Any scripts in the scripts/per-boot directory on the datasource will be run every time the system boots. Scripts will be run in alphabetical order.
I am new at using Cron Jobs on Google Cloud: I was wondering if it is possible to launch a job on an instance and have it run continuously without interruption even after I shut down my local (Laptop). Is it possible to have a job running without any ssh connection?
The CronJobs are a possibility, but they are not meant to be used in your scenario, but when you want to run a command with a certain frequency over the time.
A Bash Builtin command that suits better your needs is disown. First, run your process/script in the background (using &, or stopping it with ^Z and then restarting with bg):
$ long_operation_command &
[1] 1156
Note that at this point the process is still linked to the session and in case it is closed it will be killed.
You can the process attached to the session check running jobs in the background:
$ jobs
[1]+ Running long_operation_command
Therefore you can run disown in order to detach the processes from the session:
$ disown
You can confirm this checking the result of your script or command logging in again or checking with top the process still running.
Check also this because it could be interesting, i.e. the difference between nohup foo, foo & and $ foo & disown
P.S.
The direct answer to your question is yes, the cronjobs run even if you shutdown your laptop/shutdown the session.
I've written a TCP Server in ruby running on port 2000 with event machine.
Right now, what I do is ssh to my server and run the command ruby lib/tcp_server.rb to turn on the server, but it shuts down when I log out.
I've tried nohup and using & but nothing seems to stick for the server for a long time.
So my question is, how do I deploy this server on port 2000 and keep it running, like how we deploy Rails to nginx.
It's not a webserver, but an a tcp server for a connected device, if that helps.
Thanks!
Solution 1: tmux or screen
This is the simplest way to approach, you will have to create a tmux or screen session, then start your server in that session.
Solution 2: nohup
nohup ruby lib/tcp_server.rb > stdout.log 2> stderr.log &
You've tried nohup and using &, I suppose you've already known how to do.
Solution 3: daemonize
You can detach from the shell and daemonize the process by forking
it twice, setting the session ID and changing the current working directory.
def daemonize
exit if fork
Process.setsid
exit if fork
Dir.chdir '/'
end
With this approach, you will have to redirect stdout and stderr to keep logs.
Another way to daemonize is to use gems like daemons.
update:
To restart the process automatically after being killed, you need a process manager like god or pm2.
To start the process automatically after booting, you need to compose an init scripts but how it looks like depends on your service management system and operating system. One of the most well-known is System V. If you are using Ubuntu, you might want to take a look at Upstart or systemd.
One of our application servers (Glassfish v3.0.1) keeps crushing down with no reason. Sometimes, I am away from Internet so I cannot run it back again. Therefore, I wrote a simple bash script to wait for 10 minutes and then run asadmin. It is like:
#!/bin/bash
while true;
do sleep 600;
sudo /home/ismetb/glassfishv3.0.1/glassfish/bin/asadmin start-domain;
done
This seems to work fine however I have a couple of problems:
If I terminate the bash script (by pressing ctrl+z buttons), the Java process (Glassfish) dies and start-domain and stop-domain commands do not work at all. That means, I can neither stop Glassfish nor can I access it. I do not know if anybody else experienced this problem before or not. If the process dies, only thing I can do is to look for the ID of Java process and kill it from terminal. This not desirable at all. Any ideas why Java process dies when I quit script?
What I want to add to my script is something like to check the port Glassfish is using. If port is occupied maybe I can assume that Glassfish is not down! (However, the port (8080 default) might still be used by Glassfish although Glassfish is dead, I am not sure of it). If not, then with the help of a simple code, I can get the id of the Java process and kill them all. Then start-domain command will successfully work. Any ideas or any directions on how I can do this?
You can use a cron job instead. To install a cron job for root, enter
sudo crontab -e
and add this line
*/10 * * * * /home/ismetb/glassfishv3.0.1/glassfish/bin/asadmin start-domain
This will run asadmin every ten minutes.
If you're not comfortable with the command line, you might also try gnome-schedule, but I have no experience with that.
For your second problem, you can use curl or wget to access glassfish. You can try to get some URL, or even access the administration interface, and if you don't get a response, assume glassfish is down.
I'm writing a ruby bootstrapping script for a school project, and part of this bootstrapping process is to start a couple of background processes (which are written and function properly). What I'd like to do is something along the lines of:
`/path/to/daemon1 &`
`/path/to/daemon2 &`
`/path/to/daemon3 &`
However, that blocks on the first call to execute daemon1. I've seen references to a Process.spawn method, but that seems to be a 1.9+ feature, and I'm limited to Ruby 1.8.
I've also tried to execute these daemons from different threads, but I'd like my bootstrap script to be able to exit.
So how can I start these background processes so that my bootstrap script doesn't block and can exit (but still have the daemons running in the background)?
As long as you are working on a POSIX OS you can use fork and exec.
fork = Create a subprocess
exec = Replace current process with another process
You then need to inform that your main-process is not interested in the created subprocesses via Process.detach.
job1 = fork do
exec "/path/to/daemon01"
end
Process.detach(job1)
...
better way to pseudo-deamonize:
`((/path/to/deamon1 &)&)`
will drop the process into it's own shell.
best way to actually daemonize:
`service daemon1 start`
and make sure the server/user has permission to start the actual daemon. check out 'deamonize' tool for linux to set up your deamon.