[LINUX] Introduction to Supervisor

What is Supervisor?

A system that can control and manage processes.

Specifically, it daemonizes the process and restarts it in the event of a crash.

For example, my assigned project uses Laravel's queue worker, which is useful for continuous parallel running of programs.

Unfortunately for Windows users, it doesn't start on Windows because it's UNIX-like.

Official documentation http://supervisord.org/running.html#adding-a-program

About this article

I will write the minimum necessary contents about the basic usage of Supervisor.

Installation

This time, we will practice it on the EC2 instance launched appropriately on AWS.

Server access-superuser switching

...$ ssh -i ~/.ssh/udemy_sample2.pem [email protected]
[[email protected] ~]$ sudo su -

Install supervisor I haven't investigated it in detail, but it seems that ʻeasy_install` is good.

[[email protected] ~]# sudo easy_install supervisor
Searching for supervisor
Reading https://pypi.python.org/simple/supervisor/
Downloading https://files.pythonhosted.org/packages/ca/1f/07713b0e1e34c312450878801d496bce8b9eff5ea9e70d41ff4e299b2df5/supervisor-4.1.0-py2.py3-none-any.whl#sha256=a76b2f77a560f2dc411c0254a4eb15f555e99faac48621b0f1fc9ab013944f47
Best match: supervisor 4.1.0
Processing supervisor-4.1.0-py2.py3-none-any.whl
Installing supervisor-4.1.0-py2.py3-none-any.whl to /usr/lib/python2.7/site-packages
writing requirements to /usr/lib/python2.7/site-packages/supervisor-4.1.0-py2.7.egg/EGG-INFO/requires.txt
Adding supervisor 4.1.0 to easy-install.pth file
Installing echo_supervisord_conf script to /usr/bin
Installing pidproxy script to /usr/bin
Installing supervisorctl script to /usr/bin
Installing supervisord script to /usr/bin

Installed /usr/lib/python2.7/site-packages/supervisor-4.1.0-py2.7.egg
Processing dependencies for supervisor
Finished processing dependencies for supervisor

Creating a configuration file

[[email protected] ~]# echo_supervisord_conf > /etc/supervisord.conf

The configuration file is placed under etc.

Addition of program to be daemonized (when not managed individually)

If you do not manage the configuration files individually, add the program you want to daemonize to supervisord.conf as follows.

supervisord.conf


[program:foo]
command=/bin/cat

Addition of program to be daemonized (when managing individually)

If you want to manage the configuration files individually, follow the procedure below.

Creating a directory for storing individual program configuration files

[[email protected] ~]# mkdir /etc/supervisord.d

Modify supervisord.conf

Changes (before change)

supervisord.conf


;[include]
;files = relative/directory/*.ini

Changed part (after change)

supervisord.conf


[include]
files = /etc/supervisord.d/*.conf

Now, the individual configuration files created under /etc/supervisord.d will also be read.

Creating individual program configuration files

[[email protected] ~]# vi /etc/supervisord.d/foo.conf

Created as follows

foo.conf


[program:foo]
command=/bin/cat

About the command to use

supervisord

Used to start the supervisor.

It is not used for detailed program operations.

supervisorctl

Used in the operation of the executed program. See the URL below for detailed operation methods.

Start Supervisor ~ Run Program

Start Supervisor.

[[email protected] ~]# /usr/bin/supervisord -c /etc/supervisord.conf

It will start with just / usr / bin / supervisord, but in that case it seems better to use the c option and specify the absolute path of the configuration file because it goes to search the location of the configuration file in order. ..

Check the program in the configuration file.

[[email protected] etc]# /usr/bin/supervisorctl status
foo                              RUNNING   pid 29747, uptime 0:02:30

The program described in the configuration file seems to be executed automatically when Supervisor starts.

Try kill.

[[email protected] etc]# kill -9 29747
[[email protected] etc]# /usr/bin/supervisorctl status
foo                              RUNNING   pid 29761, uptime 0:00:03

Confirm that the process ID has changed and it has been restarted.

Try stopping the process.

[[email protected] etc]# /usr/bin/supervisorctl stop foo
foo: stopped
[[email protected] ~]# /usr/bin/supervisorctl status
foo                              STOPPED   Mar 29 01:17 AM

Make sure the process is stopped.

Try deleting the process.

[[email protected] etc]# /usr/bin/supervisorctl remove foo
foo: removed process group
[[email protected] etc]# /usr/bin/supervisorctl status
[[email protected] etc]#

Make sure the process is dead.

Add a new program and try running it in the foreground.

Add the following to supervisord.conf

supervisord.conf


[program:foo2]
command=watch -n 1 `date`

Read the configuration file and start the process

[[email protected] etc]# /usr/bin/supervisorctl reread
foo: available
foo2: available
[[email protected] etc]# /usr/bin/supervisorctl add foo2
foo2: added process group
[[email protected] etc]# /usr/bin/supervisorctl status
foo2                             RUNNING   pid 1177, uptime 0:00:04
[[email protected] etc]# /usr/bin/supervisorctl fg foo2
Every 1.0s: `date`                                      Sun Mar 29 04:24:25 2020

sh: Sun: command not found

Confirm execution in the foreground.

You can exit with Ctl + C. (Of course the process remains daemonized)

Command list

I have extracted the ones that I think I will use often.

status

Check the status of the process status.

reread

Read the configuration file.

No programs are added or removed at this stage.

add <name>

Apply the program described in the configuration file (process start).

remove <name>

Delete a stopped process.

restart <name>

Process restart.

Note that this alone will not read the contents of the configuration file.

stop

Stop the process.

start

Start the process.

update

Reload the configuration file and restart the program.

Is only the program whose settings have changed restarted?

reload

Restart the Supervisor daemon.

Summary

Convenient! !! !! !! !!

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