Learn how to use supervisor watchdog in 3 minutes

Software and hardware environment

• centos7.6.1810 64bit

  cat /etc/redhat-release #查看系统版本

• supervisor 3.4.0

• python 2.7.5

Supervisor introduction

supervisorIt is a tool pythonwritten in language 进程管理that can easily monitor, start, stop, and restart one or more processes. When a process is killed accidentally, supervisorafter monitoring the process death, the process can be easily restored automatically, no longer need programmers or system administrators to write code to control it.

supervisord installation

yum install -y epel-release
yum install -y supervisor

Start & turn on self-start

systemctl start supervisord
systemctl enable supervisord

Other commands

systemctl stop supervisord
systemctl start supervisord
systemctl status supervisord
systemctl reload supervisord
systemctl restart supervisord

supervisor's web side

supervisorProvides webcontrol based on it . Administrators can start and restart the process by clicking a button on the page, which is very convenient.

Enter the configuration file to enable support for the web

vim /etc/supervisord.conf

If it is provided for external access, you need to change the port to the local ip address

#取消10-13行注释，前面数字是行号
[inet_http_server]         ; inet (TCP) server disabled by default
port=192.168.26.121:9001   ; (ip_address:port specifier, *:port for all iface)
username=user              ; (default is no username (open server))
password=123               ; (default is no password (open server))

Restart the service after the configuration is complete

systemctl restart supervisord

supervisord application configuration

Enter supervisord configuration file

cat /etc/supervisord.conf

Seen through the last line of the configuration file

[include]
files = supervisord.d/*.ini

In other words, all our application configuration files are saved in this directory, and they are saved in the format of **.ini**, you can modify the address by yourself, but do not modify the suffix

Let's create a monitored application

Create a test python configuration

Create an application configuration named python

vim /etc/supervisord.d/python.ini

The content of the configuration file, where command is the command that needs to be executed to start our application

[program:python] #这里的python就是我们显示在web前端以及终端的监控名称
command=python /tmp/supervisordtest/test.py  #我们要监控的文件地址
autostart=true
autorestart=true
startsecs=1
startretries=3
redirect_stderr=true
stdout_logfile=/tmp/supervisordtest/access_python.log   #日志地址，可自行配置目录
stderr_logfile=/tmp/supervisordtest/error_python.log    #日志地址，可自行配置目录

Create test.py

mkdir /tmp/supervisordtest
vim /tmp/supervisordtest/test.py

Program content: open an endless loop, keep printing content

while True:
   print(100)

Restart supervisord to make the configuration file take effect

systemctl restart supervisord

Check if the application starts normally

1. Command view

systemctl status supervisord

2. Visual web view

The web terminal can restart, stop, clean up the log, view the log and other operations

Several supervisor related commands

After installation, 3 system commands will be generated supervisorctl, supervisordandecho_supervisord_conf

1. supervisord, supervisorA process supervisordis started when it is running , it is responsible for starting the managed process, and starts the managed process as its own child process, and can automatically restart when the managed process crashes

2. supervisorctl is a command line management tool that can be used to execute commands such as s tart stop restart to manage these child processes, such as

   sudo supervisorctl start demoweb
   

   Demoweb is the name of the process. For detailed commands and instructions, see the table below

   command	Description
   supervisorctl start program_name	Start a process
   supervisorctl stop program_name	Stop a process
   supervisorctl restart program_name	Restart a process
   supervisorctl status program_name	View the status of a process
   supervisorctl stop all	Stop all processes | \
   supervisorctl reload	Load the latest configuration file, restart all processes
   supervisorctl update	According to the latest configuration, restart the process that has changed the configuration, and the process that has not been updated will not be affected

3. echo_supervisord_conf

   Used to generate the default configuration file (the default configuration file, the content is very complete and has comments, suitable for reference when used, the usage is like this

echo_supervisord_conf > test.conf