UnixDaemonReloader - restarting daemons after modification configuration files!
(Update 2016.01.03)
The series "my crafts" or "re-invent the bicycle" is still continues ;)
Recently, I began creating clusters for all services of the company. For such services as mail, proxy, VoIP and etc. It needs for load balancing and fault tolerance, and it is useful for my experience and knowledge, and also for my enterprise :) I had the task to sync configuration files between cluster nodes, and also to react for changes of configuration files... For example, on the master host changed the config of postfix mail server, file replicate to the second node of the cluster, so, what is next ? We must somehow restart postfix, or rather it reload. And so, i created some scenarios of syncronization and compare files for finding differences, i wrote many scripts and methods, but there was not a unified schema. One morning I woke up and decided to make a program that work as daemon, rereading own configuration before each cycle of work, and performing prescribed actions when the specified files changed. No sooner said than done! And the name for this service - UnixDaemonReloader :)
Configuration file:
The configuration file is very simple. Path to Unix shell and the parameter allows you to execute an external command, like so: /bin/sh -c "ps ax". Then, specify a list of strings to track files and directories:
["/directory", "file", "action", "pre-app script", "result of pre-app script","error script"],
["/directory", "mask*of*the*files*", "action", "", "",""],
["/directory", "!all*files*except*this,!except*this,!and*except*this", "action"]
UDR_PreAppAttempt - Number of attempts to try execute "pre-app" scripts.
UDR_PauseBefore - pause before running the script (seconds). This setting for save your daemons from "your hands". If you during editing configuration file, accidentally press "save a file" with error or unfinished, then you have time to correct the error before the daemon will be restarted.
Sleep_Time - How much time to sleep between checks files,
SQLite_DB - SQLite_DB - the way to the base SQLite, which stores the checksums of files.
Actions may be different, not necessarily the restart, reload, or "kill -HUP". For example, can send the message to administrator :)
This program not only for clusters, but for all other systems. This helper that will save you from manual restarting a services with frequently changing configs :)
The program is written on Go language, It can be compiled from source codes for Linux, BSD, Mac, Android and other.
Source codes:
UnixDaemonReloader Source Code
Compilled binary files for FreeBSD and Linux:
UnixDaemonReloader on SourceForge
UnixDaemonReloader on My Google Drive
(Update 2016.01.03)
Recently, I began creating clusters for all services of the company. For such services as mail, proxy, VoIP and etc. It needs for load balancing and fault tolerance, and it is useful for my experience and knowledge, and also for my enterprise :) I had the task to sync configuration files between cluster nodes, and also to react for changes of configuration files... For example, on the master host changed the config of postfix mail server, file replicate to the second node of the cluster, so, what is next ? We must somehow restart postfix, or rather it reload. And so, i created some scenarios of syncronization and compare files for finding differences, i wrote many scripts and methods, but there was not a unified schema. One morning I woke up and decided to make a program that work as daemon, rereading own configuration before each cycle of work, and performing prescribed actions when the specified files changed. No sooner said than done! And the name for this service - UnixDaemonReloader :)
Configuration file:
The configuration file is very simple. Path to Unix shell and the parameter allows you to execute an external command, like so: /bin/sh -c "ps ax". Then, specify a list of strings to track files and directories:
["/directory", "file", "action", "pre-app script", "result of pre-app script","error script"],
["/directory", "mask*of*the*files*", "action", "", "",""],
["/directory", "!all*files*except*this,!except*this,!and*except*this", "action"]
Update from 2016.01.03:
Added parameters "pre-app script", "result of pre-app script" and "error script" into listing of files for watching. "Pre-app" script must to return result to stdout. Example for return: "OK" :) If returned value equals value from configuration file, will running script for restarting or reloading service, else after ending amount of attempts to execute "pre-app", will running "error script". See README.md for study new syntax of WatchList.
PS: You can add into "pre-app script" syntax check and backup configuration file. "Error script" may contain sending E-Mail or SMS and restore from backup copy of the config.
Added parameter UDR_ScriptsPath, pointing the path to pre-app scripts.
Added parameter UDR_PreAppAttempt, indicating the number of executing times the "pre-app" script, after that execute "error-script" or stop attempts.
Fixed restart for all services after first initialize database of files
Update from 2015.12.23:
UDR_PauseBefore - pause before running the script (seconds). This setting for save your daemons from "your hands". If you during editing configuration file, accidentally press "save a file" with error or unfinished, then you have time to correct the error before the daemon will be restarted.UDR_ScriptsPath - path to "pre-app" scripts
UDR_PreAppAttempt - Number of attempts to try execute "pre-app" scripts.
UDR_PauseBefore - pause before running the script (seconds). This setting for save your daemons from "your hands". If you during editing configuration file, accidentally press "save a file" with error or unfinished, then you have time to correct the error before the daemon will be restarted.
Sleep_Time - How much time to sleep between checks files,
SQLite_DB - SQLite_DB - the way to the base SQLite, which stores the checksums of files.
Actions may be different, not necessarily the restart, reload, or "kill -HUP". For example, can send the message to administrator :)
This program not only for clusters, but for all other systems. This helper that will save you from manual restarting a services with frequently changing configs :)
The program is written on Go language, It can be compiled from source codes for Linux, BSD, Mac, Android and other.
Source codes:
UnixDaemonReloader Source Code
Compilled binary files for FreeBSD and Linux:
UnixDaemonReloader on SourceForge
UnixDaemonReloader on My Google Drive
