NAME

TaskForest - Simple, powerful task scheduler

SYNOPSIS

# Run the main program, checking for jobs to run.
# By default, this will run until 23:55
#
use TaskForest;
my $task_forest = TaskForest->new();
$task_forest->runMainLoop();

OR

# Display the current status of all jobs scheduled to run today
#
use TaskForest;
my $task_forest = TaskForest->new();
$task_forest->status();

# Rerun job J_RESOLVE in family F_DNS
use TaskForest::Rerun;
rerun("F_DNS", "J_RESOLVE", $log_dir);

# Rerun job J_RESOLVE in family F_DNS
use TaskForest::Rerun;
&TaskForest::Rerun::rerun(
  "F_DNS",            # family name
  "J_RESOLVE",        # job name
  $log_dir,           # log directory
  $cascade,           # optional - apply to all dependent jobs as well
  $dependents_only,   # optional - apply to dependent jobs only
  $family_dir         # family directory
  );


# Mark job J_RESOLVE in family F_DNS as Success
use TaskForest::Mark;
&TaskForest::Mark::mark(
  "F_DNS",            # family name
  "J_RESOLVE",        # job name
  $log_dir,           # log directory
  "Success",          # status
  $cascade,           # optional - apply to all dependent jobs as well
  $dependents_only,   # optional - apply to dependent jobs only
  $family_dir         # family directory
  );

DESCRIPTION

The TaskForest Job Scheduler (TF) is a simple but expressive job scheduling system. A job is defined as any executable program that resides on the file system. Jobs can depend on each other. Jobs can also have start times before which a job may not by run. Jobs can be grouped together into "Families." A family has a start time associated with it before which none of its jobs may run. A family also has a list of days-of-the-week associated with it. Jobs within a family may only run on these days of the week.

Jobs and families are given simple names. A family is described in a family file whose name is the family name. Each family file is a text file that contains 1 or more job names. The layout of the job names within a family file determine the dependencies between the jobs (if any).

Family names and job names should contain only the characters shown below: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_

Let's see a few examples. In these examples the dashes (-), pipes (|) and line numbers are not parts of the files. They're only there for illustration purposes. The main script expects environment variables or command line options that specify the locations of the directory that contain family files, the directory that contains job files, and the directory where the logs will be written. The directory that contains family files should contain only family files.

EXAMPLE 1 - Family file named F_ADMIN

   +---------------------------------------------------------------------
01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
02 |
03 | J_ROTATE_LOGS()
04 |
   +---------------------------------------------------------------------

The first line in any family file always contains 3 bits of information about the family: the start time, the time zone, and the days on which this jobs in this family are run.

In this case, this family starts at 2:00 a.m. Chicago time. The time is adjusted for daylight savings time. This family 'runs' on Monday, Wednesday and Friday only. Pay attention to the format: it's important.

Valid days are 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'. Days must be separated by commas.

All start times (for families and jobs) are in 24-hour format. '00:00' is midnight, '12:00' is noon, '13:00' is 1:00 p.m. and '23:59' is one minute before midnight.

There is only one job in this family - J_ROTATE_LOGS. This family will start at 2:00 a.m., at which time J_ROTATE_LOGS will immediately be run. Note the empty parentheses [()]. These are required.

What does it mean to say that J_ROTATE_LOGS will be run? It means that the system will look for a file called J_ROTATE_LOGS in the directory that contains job files. That file should be executable. The system will execute that file (run that job) and keep track of whether it succeeded or failed. The J_ROTATE_LOGS script can be any executable file: a shell script, a perl script, a C program etc.

To run the program, the system actually runs a wrapper script that invokes the job script. The location of the wrapper script is specified on the command line or in an environment variable.

Now, let's look at a slightly more complicated example:

EXAMPLE 2 - Job Dependencies

This family file is named WEB_ADMIN

   +---------------------------------------------------------------------
01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
02 |
03 |               J_ROTATE_LOGS()
04 |
05 | J_RESOLVE_DNS()               Delete_Logs_Older_Than_A_Year()
06 |
07 |               J_WEB_REPORTS()      
08 |
09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
10 |
   +---------------------------------------------------------------------

A few things to point out here: - Blank lines are ignored. - A hash (#) and anything after it, until the end of the line is treated as a comment and ignored - Job and family names do not have to start with J_ or be in upper case.

Now then, all jobs on a single line are started AT THE SAME TIME. All jobs on a line are started only when all jobs on the previous line are executed successfully. If there are no jobs on a previous line (as in the case of line 3 above), all jobs on that line are started when the family starts (2:00 a.m. above). There is an exception to this rule that we'll see in the next example.

So the above family can be interpreted in English as follows: "All WEB_ADMIN jobs are eligible to run after 2:00 a.m Chicago time on Mondays, Wedesdays and Fridays. The first job to be run is J_ROTATE_LOGS. If that succeeds, then J_RESOLVE_DNS and Delete_Logs_Older_Than_A_Year are started at the same time. If both these jobs succeed, then J_WEB_REPORTS is run. If that job succeeds, the J_EMAIL_WEB_RPT_done is run."

EXAMPLE 3 - TIME DEPENDENCIES

Let's say tha twe don't want J_RESOLVE_DNS to start before 9:00 a.m. because it's very IO-intensive and we want to wait until the relatively quiet time of 9:00 a.m. In that case, we can put a time dependency of the job. This adds a restriction to the job, saying that it may not run before the time specified. We would do this as follows:

   +---------------------------------------------------------------------
01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
02 |
03 |               J_ROTATE_LOGS()
04 |
05 | J_RESOLVE_DNS(start => '09:00')    Delete_Logs_Older_Than_A_Year()
06 |
07 |               J_WEB_REPORTS()      
08 |
09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
10 |
   +---------------------------------------------------------------------

J_ROTATE_LOGS will still start at 2:00, as always. As soon as it succeeds, Delete_Logs_Older_Than_A_Year is started. If J_ROTATE_LOGS succeeds before 09:00, the system will wait until 09:00 before starting J_RESOLVE_DNS. It is possible that Delete_Logs_Older_Than_A_Year would have started and complete by then. J_WEB_REPORTS would not have started in that case, because it is dependent on two jobs, and both of them have to run successfully before it can run.

For completeness, you may also specify a timezone for a job's time dependency as follows:

05 | J_RESOLVE_DNS(start=>'10:00', tz=>'America/New_York')  Delete_Logs_Older_Than_A_Year()

EXAMPLE 4 - JOB FORESTS

You can see in the example above that line 03 is the start of a group of dependent job. No job on any other line can start unless the job on line 03 succeeds. What if you wanted two or more groups of jobs in the same family that start at the same time (barring any time dependencies) and proceed independently of each other?

To do this you would separate the groups with a line containing one or more dashes (only). Consider the following family:

   +---------------------------------------------------------------------
01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
02 |
03 |               J_ROTATE_LOGS()
04 |
05 | J_RESOLVE_DNS(start => '09:00')    Delete_Logs_Older_Than_A_Year()
06 |
07 |               J_WEB_REPORTS()      
08 |
09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
10 |
11 |----------------------------------------------------------------------
12 |
13 | J_UPDATE_ACCOUNTS_RECEIVABLE()
14 |
15 | J_ATTEMPT_CREDIT_CARD_PAYMENTS()
16 |
17 |----------------------------------------------------------------------
18 |
19 | J_SEND_EXPIRING_CARDS_EMAIL()
20 |
   +---------------------------------------------------------------------

Because of the lines of dashes on lines 11 and 17, the jobs on lines 03, 13 and 19 will all start at 02:00. These jobs are independent of each other. J_ATTEMPT_CREDIT_CARD_PAYMENT will not run if J_UPDATE_ACCOUNTS_RECEIVABLE fails. That failure, however will not prevent J_SEND_EXPIRING_CARDS_EMAIL from running.

Finally, you can specify a job to run repeatedly every 'n' minutes, as follows:

   +---------------------------------------------------------------------
01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
02 |
03 | J_CHECK_DISK_USAGE(every=>'30', until=>'23:00')
04 |
   +---------------------------------------------------------------------

This means that J_CHECK_DISK_USAGE will be called every 30 minutes and will not run on or after 23:00. By default, the 'until' time is 23:59. If the job starts at 02:00 and takes 25 minutes to run to completion, the next occurance will still start at 02:30, and not at 02:55. By default, every repeat occurrance will only have one dependency - the time - and will not depend on earlier occurances running successfully or even running at all. If line 03 were:

03 | J_CHECK_DISK_USAGE(every=>'30', until=>'23:00', chained=>1)

...then each repeat job will be dependent on the previous occurance.

USAGE

There are a few simple scripts in the bin directory that simplify usage. To run the program you must let it know where it can find the necessary files and directories. This can be done by environment variables, or via the command line:

export TF_JOB_DIR=/foo/jobs
export TF_LOG_DIR=/foo/logs
export TF_FAMILY_DIR=/foo/families
export TF_RUN_WRAPPER=/foo/bin/run
taskforest

OR

taskforest -run_wrapper=/foo/bin/run \
  --log_dir=/foo/logs \
  --job_dir=/foo/jobs \
  --family_dir=/foo/families

All jobs will run as the user who invoked taskforest.

You can rerun jobs or mark jobs as Success or Failure using the 'rerun' and 'mark' commands as shown below.

OPTIONS

The following command line options are required. If they are not specified on the command line, the environment will be searched for corresponding environment variables.

--run_wrapper=/a/b/r  [or environment variable TF_RUN_WRAPPER]

  This is the location of the run wrapper that is used to execute the
  job files.  The run wrapper is also responsible for creating the
  semaphore files that denote whether a job ran successfully or not.
  You can use the provided run wrapper (bin/run).  If you need more
  functionality, like logging status to a database, you can create
  your own run wrapper, as long as it preserves the functionality of
  the default run_wrapper.   

--log_dir=/a/b/l  [or environment variable TF_LOG_DIR]

  This is called the root log directory.  Every day a dated directory
  named in the form YYYYMMDD will be created and the semaphore files
  will be created in that directory.

--job_dir=/a/b/j  [or environment variable TF_JOB_DIR]

  This is the location of all the job files.  Each job file should be
  an executable file (e.g.: a binary file, a shell script, a perl or
  python script).  The file names are used as job names in the family
  configuration files.  Job names may only contain the characters
  a-z, A-Z, 0-9 and _.  You may create aliases to jobs within this
  directory.

  If a job J1 is present in a family config file, any other
  occurrance of J1 in that family refers TO THAT SAME JOB INSTANCE.
  It does not mean that the job will be run twice.

  If you want the same job running twice, you will have to put it in
  different families, or make soft links to it and have the soft
  link(s) in the family file along with the actual file name.

  If a job is to run repeatedly every x minutes, you could specify
  that using the 'repeat/every' syntax shown above.

--family_dir=/a/b/f  [or environment variable TF_FAMILY_DIR]

  This is the location of all the family files.  As is the case with
  jobs, family names are the file names.  Family names may only
  contain the characters a-z, A-Z, 0-9 and _.

The following command line options are optional

--once_only

  If this option is set, the system will check each family once, run
  any jobs in the Ready state and then exit.  This is useful for
  testing, or if you want to invoke the program via cron or some
  similar system, or if you just want the program to run on demand,
  and not run and sleep all day.

--end_time=HH:MM

  If once_only is not set, this option determines when the main
  program loop should end.  This refers to the local time in 24-hour
  format.  By default it is set to 23:55.  This is the recommended
  maximum.

--wait_time

  This is the amount of seconds to sleep at the end of every
  loop. The default value is 60.

--verbose

  Print a lot of debugging information

--help

  Display help text

--log

  Log stdout and stderr to files

--log_threshold=t

  Log messages at level t and above only will be printed to the
  stdout log file.  The default value is "warn".

--log_file=o

  Messages printed to stdout are saved to file o in the log_directory
  (if --log is set).  The default value is "stdout".

--err_file=e

  Messages printed to stderr are saved to file e in the log_directory
  (if --log is set).  The default value is "stderr".

--config_file=f

  Read configuration settings from config file f.

--chained

  If this is set, all recurring jobs will have the chained attribute
  set to 1 unless specified explicitly in the family file. 

--collapse

  If this option is set then the status command will behave as if the
  --collapse options was specified on the command line.

DISPLAY STATUS

To get the status of all currently running and recently run jobs, enter the following command:

status

OR

status --log_dir=/foo/logs --family_dir=/foo/families

OR

status --log_dir=/foo/logs --family_dir=/foo/families --collapse

If the --collapse option is used then pending repeat jobs will not be displayed.

RERUN A JOB

To rerun a job, enter the following command:

rerun --log_dir=l_d --job=Ff::Jj

where l_d is the log directory and Ff is the family name and Jj is the job name.

If you run the command like this:

rerun --log_dir=l_d --job=Ff::Jj --cascade --family_dir=f_d

then all the jobs that are directly or indirectly dependent on job Jj in family Ff will also be rerun.

If you run the command like this:

rerun --log_dir=l_d --job=Ff::Jj --dependents_only --family_dir=f_d

then only those jobs that are directly or indirectly dependent on job Jj in family Ff will be rerun. Job Jj will be unaffected.

MARK A JOB SUCCESS OR FAILURE

To mark a previously-run job as success or failure, enter the following command:

mark --log_dir=l_d --job=Ff::Jj --status=s

where l_d is the log directory and Ff is the family name, Jj is the job name, and s is 'Success' or 'Failure'.

If you run the command like this:

mark --log_dir=l_d --job=Ff::Jj --status=s --cascade --family_dir=f_d

then all the jobs that are directly or indirectly dependent on job Jj in family Ff will also be marked.

If you run the command like this:

mark --log_dir=l_d --job=Ff::Jj --status=s --dependents_only --family_dir=f_d

then only those jobs that are directly or indirectly dependent on job Jj in family Ff will be marked. Job Jj will be unaffected.

READING OPTIONS FROM A CONFIG FILE

The 'taskforest' and 'status' commands now accept a "--config_file=f" option. You can now specify commonly used options in the config file, so you do have to include them on the command line. The config file should contain one option per command line. The following sample config file shows the list of all supported options, and documents their usage.

# ########################################
# SAMPLE CONFIG FILE
# ########################################
# These are the four required command line arguments to taskforest
log_dir         = "t/logs"
family_dir      = "/usr/local/taskforest/families"
job_dir         = "/usr/local/taskforest/jobs"
run_wrapper     = "/usr/local/bin/run"

# wait this many seconds between iterations of the main loop
wait_time       = 60

# stop taskforest at this time of day
end_time        = 2355

# if set to 1, run taskforest once only and exit immediately after that
once_only       = 0

# print out extra logs - may be redundant, due to log_threshold, below
# THIS OPTION WILL BE DEPRECATED SOON.
verbose         = 0

# by default assume that the --collapse option was given to the status command
collapse        = 1  # change from previously default behavior

# by default assume that all repeating jobs have the --chained=>1 attribute set
chained         = 1  # change from previously default behavior

# log stdout and stderr to files
log             = 1

# by default, log stdout messages with status >= this vale.
# This only effects stdout
# The sequence of thresholds (smallest to largest) is:
# debug, info, warn, error, fatal
log_threshold   = "warn"

# The log_file and err_file names should NOT end with '.0' or '.1' 
# because then they will be mistaken for job log files
log_file        = "stdout"  
err_file        = "stderr"  

# currently unused
log_status      = 0

PRECEDENCE OF DIFFERENT OPTIONS SOURCES

All settings (required and optional) may be specified in a variety of ways: command line, environment variable and config file. The order of preferences is this: Most options have default values. Settings specified in the config file override those defaults. Settings specified in environment variables take override those specified in the config file and the default values. Setting specified on the command line override those specified in envrionment variables, and those specified in the config files and the default values.

The names of the environment variable are the same as the names of the settings on the command line (or in the config file), but they should be in UPPER CASE, with "TF_" prepended. For example, the environment variable name for the 'run_wrapper' setting is 'TF_RUN_WRAPPER'.

LOGGING STDOUT AND STDERR

If the --log option is set, then anything printed to stdout and stderr will be saved to log files. Before the logging start, the program will print onto stdout the names of the log file and error file. The program logs incidents at different levels ("debug", "info", "warning", "error" and "fatal"). The "log_threshold" option sets the level at which logs are written to the stdout file. If the value of log_threshold is "info", then only those log messages with a level of "info" or above ("warning", "error" or "fatal") will be written to the stdout log file. The stderr log file always has logs printed at level "error" or above, as well as anything printed explicitly to STDERR.

The log file and error file will be saved in the log_directory.

BUGS

For an up-to-date bug listing and to submit a bug report, please visit our website at http://sourceforge.net/projects/taskforest/

SUPPORT

For support, please visit our website at http://sourceforge.net/projects/taskforest/

AUTHOR

Aijaz A. Ansari http://sourceforge.net/projects/taskforest/

If you're using this program, I would love to hear from you. Please visit our project website and let me know what you think of it.

COPYRIGHT

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself - specifically, the Artistic License.

The full text of the license can be found in the LICENSE file included with this module.

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NAME

SYNOPSIS

DESCRIPTION

EXAMPLE 1 - Family file named F_ADMIN

EXAMPLE 2 - Job Dependencies

EXAMPLE 3 - TIME DEPENDENCIES

EXAMPLE 4 - JOB FORESTS

USAGE

OPTIONS

DISPLAY STATUS

RERUN A JOB

MARK A JOB SUCCESS OR FAILURE

READING OPTIONS FROM A CONFIG FILE

PRECEDENCE OF DIFFERENT OPTIONS SOURCES

LOGGING STDOUT AND STDERR

BUGS

SUPPORT

AUTHOR

COPYRIGHT

SEE ALSO

Module Install Instructions