How to use the command supervisorctl (with examples)
Supervisorctl is a command-line client for the Supervisor system, which allows users to control multiple processes on UNIX-like operating systems. It provides a shell-like interface for managing these processes.
Use case 1: Show the status of a process (or all processes if process_name is not specified)
Code:
supervisorctl status process_name
Motivation: This command is useful for checking the status of a specific process or all processes managed by Supervisor. It allows users to quickly determine whether a process is running or stopped, and can be used for monitoring purposes.
Explanation: The status argument is used to display the status of a process. If the process_name is specified, it will show the status of that particular process. If process_name is not specified, it will display the status of all processes.
Example output:
process_name RUNNING pid XXXX, uptime X days X hours X minutes
Use case 2: Start/stop/restart a process
Code:
supervisorctl start|stop|restart process_name
Motivation: This command allows users to start, stop, or restart a specific process managed by Supervisor. It is useful for managing the lifecycle of individual processes.
Explanation: The start, stop, and restart arguments are used to start, stop, or restart a process respectively. The process_name argument specifies the name of the process to be started, stopped, or restarted.
Example output:
process_name: started
Use case 3: Start/stop/restart all processes in a group
Code:
supervisorctl start|stop|restart group_name:*
Motivation: This command allows users to start, stop, or restart all processes within a specific process group managed by Supervisor. It is useful for managing multiple related processes at once.
Explanation: The start, stop, and restart arguments are used to start, stop, or restart all processes within a specified process group. The group_name:* argument specifies the name of the group, followed by :* to indicate all processes within the group.
Example output:
group_name: stopped
Use case 4: Show last 100 bytes of process stderr
Code:
supervisorctl tail -100 process_name stderr
Motivation: This command allows users to view the last 100 bytes of the stderr output of a specific process managed by Supervisor. It is useful for troubleshooting purposes.
Explanation: The tail argument is used to display the last 100 bytes of a specified process’s stderr output. The process_name argument specifies the name of the process, and the stderr argument specifies the stderr stream.
Example output:
Error: NullPointerException
Use case 5: Keep displaying stdout of a process
Code:
supervisorctl tail -f process_name stdout
Motivation: This command allows users to continuously monitor and display the stdout output of a specific process managed by Supervisor. It is useful for observing and analyzing real-time process output.
Explanation: The tail argument with the -f flag is used to continuously display the stdout output of a specified process. The process_name argument specifies the name of the process, and the stdout argument specifies the stdout stream.
Example output:
INFO: Process is running...
INFO: Process is running...
Use case 6: Reload process config file to add/remove processes as necessary
Code:
supervisorctl update
Motivation: This command allows users to reload the Supervisor process configuration file, which can be used to add or remove processes as necessary. It is useful when making changes to the process configuration without restarting Supervisor.
Explanation: The update argument is used to reload the process configuration file. This can be useful when changes are made to the configuration file and need to be applied without restarting Supervisor.
Example output:
Configuration successfully reloaded.
Conclusion
The supervisorctl command is a powerful tool for managing and controlling processes using Supervisor. It provides a convenient command-line interface for monitoring process status, starting/stopping/restarting processes, displaying process output, and updating process configurations. By understanding the various use cases of this command, users can effectively manage their processes and ensure smooth operations.
