Observer Service Tool

The observer service tool is used as a wrapper for hourly, daily, weekly, and monthly cron-jobs. The observer service tool is able to execute cronjobs for several different users on the system using their privileges only. The output of these cron-jobs is summarized. You will receive one single email from the observer service tool that provides a short summary of the executed tasks, which quickly informs you about differences to the previous execution of the task, normal operation or exceptions or errors during execution of individual scripts. The full output of the cron-jobs is appended to this email and additional log files may be created by the tasks in dedicated directories.

observer.cfg

observer.pl*
observer.hourly.pl -> observer.pl*
observer.daily.pl -> observer.pl*
observer.weekly.pl -> observer.pl*
observer.monthly.pl -> observer.pl*

observer_mkdir.pl*

The observer-tool comes with four synonyms (which have to match the settings in the config file - see below). The typical usage is to call 'observer.hourly.pl' from /etc/cron.hourly, 'observer.daily.pl' from /etc/cron.daily and so on. The observer script should run under root privileges as it has to su to user accounts. In the user accounts it looks for observer scripts matching the given interval and executes them. It checks for the scripts or programs to match the UID of the user account and to be not writable by others. The observer tool collects reports from these scripts, sorts them within one report and logs the report. It may also send the report via e-mail to an admin.

The config file defines the user accounts to include in the action. It has to be named $HOME/observer/observer.cfg or the name has to be provided in the environment variable $OBSERVER_CONFIG.

Settings in observer.cfg:

$OBSERVER_CLIENT:

This is a hash table that defines the user accounts to include in the action and defines the directories where to look for scripts or programs.

$OBSERVER_OKREPORT:

This hash defines the callable intervals (hourly,...) and which report levels should be mailed.

$OBSERVER_NOTIFY:

This string variable defines to e-mail addresses of user to send the report to.

$OBSERVER_LOGDIR:

This string variable defines a log dir for the master logs.

Below the directory defined in $OBSERVER_CLIENT the tool expects a subdirectory structure like this:

./scripts
./scripts/weekly
./scripts/monthly
./scripts/daily
./scripts/hourly
./log
./log/weekly
./log/monthly
./log/daily
./log/hourly

Where it expects to find executable scripts in ./scripts/hourly, etc. The client service job scripts or programs have to be executable (file mode bit set) and must not end with '.bak'.

The scripts and programs are called with the following environment variables set:

OBS_CLIENT            the service client (i.e. the user that owns the script)
OBS_LOG_DIR           the proposed directory for user level log files
OBS_SCRIPT_DIR        the directory where the script was found
OBS_LOG               the full pathname of the proposed log file
OBS_SCRIPT            the full pathname of the script

OBS_KEY_STATUS        a string indicating a status level ('status:')
OBS_KEY_MESSAGE       a string indicating a status message ('message:')

OBS_KEY_OK            the ok level index ('O')
OBS_KEY_NOTICE        the notice level index ('N')
OBS_KEY_ALERT         the alert level index ('A')

OBS_STATUS_OK         a full status level string ('status: O')
OBS_STATUS_NOTICE     a full status level string ('status: N')
OBS_STATUS_ALERT      a full status level string ('status: A')

The status level indices ('ONA') are used to define report level to send via e-mail in $OBSERVER_OKREPORT.

The client service script or program has to return a success or status message through stdout. It has to produce two lines in the following scheme:

echo $OBS_STATUS_OK
echo $OBS_KEY_MESSAGE this is an example message...

These values will be used to create a quick status index of all service jobs. The idea of the three status levels is to give the admin an idea how to react:

OK:       the service was executed successfull, no further action is needed
NOTICE:   there happend something that is unusual, but is not dangerous;
          please have a closer look
ALERT:    the service met an error condition, immediate action might be
          required!

In addition to the status level the client service may write more lines to stdout or stderr. All these lines will be catched and appended to the observer-tool log and report.

It is up to the client service tool to create additional logs and reports. The preferred name for a report file is given in $OBS_LOG and will be unique to one run of the observer-tool (i.e. it has a time stamp in the file name that includes the hour at least).

Starting with version 1.6 the observer call /bin/bash as login shell for its su-clients.

The observer_mkdir.pl tool

After setting up observer.cfg this tool will create all client directories that are expected by observer.pl.