Process Supervisor

Supervisor is a client server system that allows its users to control a number of processes on UNIX-like operating systems It was inspired by the following Convenience It is often inconvenient to need to write rc d scripts for every single process instance rc d scripts are a great lowest-common-denominator form of process initialization autostart management but they can be painful to write and maintain Additionally rc d scripts cannot automatically restart a crashed process and many programs do not restart themselves properly on a crash Supervisord starts processes as its subprocesses and can be configured to automatically restart them on a crash It can also automatically be configured to start processes on its own invocation Accuracy It s often difficult to get accurate up down status on processes on UNIX Pidfiles often lie Supervisord starts processes as subprocesses so it always knows the true up down status of its children and can be queried conveniently for this data Delegation Users who need to control process state often need only to do that They don t want or need full-blown shell access to the machine on which the processes are running Processes which listen on low TCP ports often need to be started and restarted as the root user a UNIX misfeature It s usually the case that it s perfectly fine to allow normal people to stop or restart such a process but providing them with shell access is often impractical and providing them with root access or sudo access is often impossible It s also rightly difficult to explain to them why this problem exists If supervisord is started as root it is possible to allow normal users to control such processes without needing to explain the intricacies of the problem to them Supervisorctl allows a very limited form of access to the machine essentially allowing users to see process status and control supervisord-controlled subprocesses by emitting stop start and restart commands from a simple shell or web UI Process Groups Processes often need to be started and stopped in groups sometimes even in a priority order It s often difficult to explain to people how to do this Supervisor allows you to assign priorities to processes and allows user to emit commands via the supervisorctl client like start all and restart all which starts them in the preassigned priority order Additionally processes can be grouped into process groups and a set of logically related processes can be stopped and started as a unit Features Simple Supervisor is configured through a simple INI-style config file that s easy to learn It provides many per-process options that make your life easier like restarting failed processes and automatic log rotation Centralized Supervisor provides you with one place to start stop and monitor your processes Processes can be controlled individually or in groups You can configure Supervisor to provide a local or remote command line and web interface Efficient Supervisor starts its subprocesses via fork exec and subprocesses don t daemonize The operating system signals Supervisor immediately when a process terminates unlike some solutions that rely on troublesome PID files and periodic polling to restart failed processes Extensible Supervisor has a simple event notification protocol that programs written in any language can use to monitor it and an XML-RPC interface for control It is also built with extension points that can be leveraged by Python developers Compatible Supervisor works on just about everything except for Windows It is tested and supported on Linux Mac OS X Solaris and FreeBSD It is written entirely in Python so installation does not require a C compiler Proven While Supervisor is very actively developed today it is not new software Supervisor has been around for years and is already in use on many servers Supervisor Components supervisord The server piece of supervisor is named supervisord It is responsible for starting child programs at its own invocation responding to commands from clients restarting crashed or exited subprocesseses logging its subprocess stdout and stderr output and generating and handling events corresponding to points in subprocess lifetimes The server process uses a configuration file This is typically located in etc supervisord conf This configuration file is a Windows-INI style config file It is important to keep this file secure via proper filesystem permissions because it may contain unencrypted usernames and passwords supervisorctl The command-line client piece of the supervisor is named supervisorctl It provides a shell-like interface to the features provided by supervisord From supervisorctl a user can connect to different supervisord processes one at a time get status on the subprocesses controlled by stop and start subprocesses of and get lists of running processes of a supervisord The command-line client talks to the server across a UNIX domain socket or an internet TCP socket The server can assert that the user of a client should present authentication credentials before it allows him to perform commands The client process typically uses the same configuration file as the server but any configuration file with a supervisorctl section in it will work Web Server A sparse web user interface with functionality comparable to supervisorctl may be accessed via a browser if you start supervisord against an internet socket Visit the server URL e g http localhost 9001 to view and control process status through the web interface after activating the configuration file s inet http server section XML-RPC Interface The same HTTP server which serves the web UI serves up an XML-RPC interface that can be used to interrogate and control supervisor and the programs it runs See JOB APPLY http jobs vinayakjob com CONTACT DETAILS - Name - DIMPAL Number - 91 91099 99669