Abstract

This is a simple file monitoring daemon. It is configured with Event Definitions that basically say which file patterns the daemon should react on, and what the resulting action should be.

Features

• Pure Python
• Works without inotify (Linux only) on Windows, Unix and Linux OSes.
• Uses "modified" stat() metadata and file size comparison to detect if a file is closed / fully written to disk. If the file size does not change within a tracking interval, it is considered to be closed (of course it depends on the application when the file is closed, so this parameter needs to be configured per-Event Definition)
• Can be configured to reload its config file dynamically
• Event Definitions that have a (repeatedly) failing Action can be disabled automatically
• One Python file and one YAML config file; easy to deploy or modify

Dependencies

• Python > 2.6
• PyYAML

Usage

Usage: monitor.py
          [-t|--test]             : Run test mode (use this to create a sample config file)
          [-i N|--interval=N]     : Polling interval of N seconds [5]
          [-c file|--config=file] : Use YAML config file [config.yaml]
          [-d|--dynamic]          : Enable dynamic config file reload
          [-v|--verbose]          : Print debug messages
          [-h|--help]             : Print this help message
          [-l|--logging]          : Enable file logging, default is console only
          [--backupcount=N]       : Keep N logfiles (rotate) [5]
          [--logfilesize=N]       : Rotate logfile when N bytes in size [100000]
          [--logfilename=file]    : Log file name [monitor.out]

Actions

When defining actions, you can reference the event and its definition by enclosing them in curly braces, for example to reference the directory (eventdef.dir) and the actual file name (event.filename):

- !!python/object:__main__.EventDef {
        action: 'echo "{eventdef.dir}" >> /tmp/hallo.out; ls -l /tmp/{event.filename}', 
        dir: /tmp, 
        maxerrors: 2, 
        minsize: 0, 
        pattern: hallo.*\.txt,
        tracking_interval: 60
   }

The following properties can be defined:

• action: The command that should be executed if the file is detected.
• dir: The directory that is monitored for new files.
• maxerrors: The action is executed that much times if it yields an error (exit status other that 0)
• minsize: Event will only be triggered if the file size is larger than this parameter (in bytes)
• tracking_interval: the file is checked every tracking_interval seconds if it changed (to determine if it is closed or still written to).