API Documentation

crawler

class cronster.crawler.CronsterCrawler(root, cache_host, cache_port, interval)

Bases: object

Cronster crawler class. Crawl the file system recursively for crontab files, read the contents and store a list of CronsterJob in a Redis cache.

__init__(root, cache_host, cache_port, interval)

Initialise a CronsterCrawler.

Parameters:

• root (str) – File system root to crawl
• cache_host (str) – Host that serves the Redis cache
• cache_port (int) – Port on the host that exposes the Redis service
• interval (int) – Time between crawls in seconds

crawl()

Recursively crawl the file system from root in a given interval. Add CronsterJob from crontab files to the cache as a JSON string.

display_crontabs()

Print the current cache content to the console in tabulated form.

get_crontab_data(crontab)

Given a crontab file path, load and return the CronsterJob contained in the file.

Parameters:crontab (str) – Crontab file path Returns:Jobs Return type:list

Example output:

[
    {
        "name": "job_name",
        "cmd": "echo $PATH",
        "schedule": "* * * * *",
        "path": "/path/to/crontab/file",
        "hash": "dc8a776c99d9b8ab97550e87c857dc959a857c5b"
    }
]

scheduler

class cronster.scheduler.CronsterJob(job_name, job_cmd, job_schedule, job_path, job_hash)

Bases: object

Cronster job class. Representation of an individual cronster job.

__init__(job_name, job_cmd, job_schedule, job_path, job_hash)

Initialise a CronsterJob.

Parameters:

• job_name (str) – Job name
• job_cmd (str) – Job command
• job_schedule (str) – Job schedule in cron format, e.g. */5 * * * *
• job_path (str) – Job’s crontab file path
• job_hash (str) – Job hash

__lt__(other)

_execute_command()

Execute the job’s command as a subprocess.

cmd

Returns:Job command Return type:str

cron

Returns:Job schedule Return type:str

hash

Returns:Job hash Return type:str

is_due

Returns:Whether or not the job is due to be run. Return type:bool

name

Returns:Job name Return type:str

path

Returns:Job crontab file path Return type:str

run()

Run the job and schedule the next run.

schedule()

Calculate the next run time and schedule the job to run.

status

Returns:Job status Return type:bool

class cronster.scheduler.CronsterScheduler(cache_host, cache_port)

Bases: object

Cronster scheduler class. Load jobs from a Redis cache and run any number of CronsterJob based on their schedule.

__init__(cache_host, cache_port)

Initialise a CronsterScheduler.

Parameters:

• cache_host (str) – Host that serves the Redis cache
• cache_port (int) – Port on the host that exposes the Redis service

clear()

Clear the job queue.

run_pending()

Run all pending jobs.

start()

Start the scheduler. Jobs will be run according to their schedule.

status()

Return the current status of all scheduler jobs.

Returns:Job data Return type:tuple

stop()

Stop the scheduler. Jobs will not be running regardless of their schedule.

update()

Load the current cache contents, add jobs or change jobs’ statuses.

class cronster.scheduler.CronsterSchedulerPrompt(scheduler)

Bases: cmd.Cmd

Cronster command prompt class. Implement CLI commands to control the attached CronsterScheduler.

__init__(scheduler)

Initialise a CronsterSchedulerPrompt.

Parameters:scheduler (CronsterScheduler) – Scheduler to control

do_clear(args)

Invoke cronster.scheduler.CronsterScheduler.clear() to clear the job queue.

do_exit(args)

Close the scheduler.

do_start(args)

Invoke cronster.scheduler.CronsterScheduler.start() to start the scheduler.

do_status(args)

Invoke cronster.scheduler.CronsterScheduler.status() and print the status information to the console.

do_stop(args)

Invoke cronster.scheduler.CronsterScheduler.stop() to stop the scheduler.

do_update(args)

Invoke cronster.scheduler.CronsterScheduler.update() to force a job update form the cache.

cronster.scheduler._update_loop(scheduler)

Run an infinite update/run loop.

Parameters:scheduler (CronsterScheduler) – Scheduler to run

cronster.scheduler.run_scheduler(cache_host, cache_port)

Instantiate and run a CronsterScheduler. Run its run/update loop in a separate thread.

Parameters:

• cache_host (str) – Host that serves the Redis cache
• cache_port (int) – Port on the host that exposes the Redis service