Slavedriver

A PHP based cron job runner. Manage, monitor, log and react to problems with your scheduled tasks. Created by the team at deploy.dog initially for internal use, but modified and released for other to enjoy too. Created by deploy.dog initially for internal use, but released for others to enjoy too.

Requirements

• PHP 5.6, 7.0, 7.1 or HHVM
• Unix based OS such as Linux, FreeBSD or MacOS (Windows is not supported at this time)

Installation (via Composer obviously)

composer require deploy-dog/slavedriver

Usage

Create your file which describes your jobs.

We suggest using a file named slavedriver.php in the project root, and that's what we'll be using in this example.

A more detailed example of this file can be seen here, but the basics are below

// You'll need autoloading
require_once __DIR__ . '/vendor/autoload.php';

// We recommend scrapbook for your PSR-16 compatible cache, but use whatever you like!
// This example is using Scrapbook and Flysystem to write a cache file to the disk, but you'll
// probably want to use Redis or something better like that
$adapter = new \League\Flysystem\Adapter\Local('/tmp/dd.slavedriver.cache', LOCK_EX);
$filesystem = new \League\Flysystem\Filesystem($adapter);
$cache = new \MatthiasMullie\Scrapbook\Adapters\Flysystem($filesystem);
$simpleCache = new \MatthiasMullie\Scrapbook\Psr16\SimpleCache($cache);

// In this example, we use phossa2/event which is a PSR-14 event manager.
// PSR-14 is only "proposed" at this stage. Once PSR-14 is "accepted" we'll update the required interface.
// You can use anything that implments \Phossa2\Event\Interfaces\EventManagerInterface (which is a copy of PSR-14),
// it doesn't actually have to be phossa2/event
$eventsDispatcher = new \Phossa2\Event\EventDispatcher();
$eventsDispatcher->attach(\deploydog\Slavedriver\Slavedriver::EVENT_SLAVEDRIVER_ALL, function(\Phossa2\Event\Event $event) {
    $job = $event->getTarget();
    // See Events in the readme below for details on events
});

// Instantiate Slavedriver
$slavedriver = new \deploydog\Slavedriver\Slavedriver($simpleCache, $eventsDispatcher);

// Want logging (in addition to events)? See the Logging section of the readme below

// You can set the Slave Name that the machine running this job has (so it know which jobs to do).
// We'll look at the following (in this order)
// Manually set using $slavedriver->setSlaveName()
// Environment var "SLAVEDRIVER_SLAVE_NAME"
// Node hostname (from php's gethostname() function)
$slavedriver->setSlaveName('test1');

// Create a job
$job = new \deploydog\Slavedriver\Job('Sleep for a bit');
$job->setCommand('sleep 10');
$job->setTimeout(14);
$job->setWarnIfNotFinishedAfterSeconds(11);
$job->setSchedule('* * * * *');
$job->setSlaves(['test1']); // Optional, default to all slaves

// Add the job to Slavedriver
$slavedriver->addJob($job);

// Add more jobs like with the example above..

// Alternatively (or in addition) if you have lots of jobs you might want to include one per file
// and get Slavedriver to recursively look in directory for jobs
// Your included files should return an instance of the Job object.
$slavedriver->addAllJobsInDirectory(__DIR__.'/DirWithJobs');

// Run the required jobs
$slavedriver->run();

Running Slavedriver

You need to get something (e.g. the real system crontab) to run your Slavedriver file every 1 minute (this time internal is important, don't change it).

* * * * * cd /path/to/project && php slavedriver.php 1>> /dev/null 2>&1

Events

Events are dispatched throughout the process which you can listen to. You can use any PSR-14 (Event Manager) compatible event manager. PSR-14 is currently at the "proposed" stage so we should expect it to change. We'd recommend using phossa2/event as your PSR-14 event manager if you don't have one currently and don't want to implement your own. As PSR-14 is not out yet, we require a class which implements Phossa2\Event\Interfaces\EventManagerInterface so if you don't want to use phossa2/event you can write something else which implements that same class. Not ideal, I know, and we expect to change this in v2 when PSR-14 is approved.

You can listen to the follow events to monitor your Slavedriver jobs and act accordingly.

Hint: Use the Job's CustomData if you want to pass through additional data, such as whether to wake people up in the night if the job fails!

Catching events

Handling specific events

$eventsDispatcher = new \Phossa2\Event\EventDispatcher(); // This is the same one you passed into Slavedriver on construct
$eventsDispatcher->attach(\deploydog\Slavedriver\Slavedriver::EVENT_JOB_OUTPUT_STDOUT, function(\Phossa2\Event\Event $event) {
     $job = $event->getTarget();
     $stdOut = $event->getParam('stdOut');
    
     // Log $stdOut somewhere, this can be called multiple times for each job and will be given any
     // new stdOut since the last call. You can then append this to the previous stdOut of the job
     // Likewise the event "slavedriver.job.output.stderr" will give you the stdErr in $event->getParam('stdErr')
});

Handling all Slavedriver events

$eventsDispatcher = new \Phossa2\Event\EventDispatcher(); // This is the same one you passed into Slavedriver on construct
$eventsDispatcher->attach(\deploydog\Slavedriver\Slavedriver::EVENT_SLAVEDRIVER_ALL, function(\Phossa2\Event\Event $event) {
    $job = $event->getTarget();

    if ($job instanceof \deploydog\Slavedriver\Job) {
        echo 'Got event "'.$event->getName().'" on job "'.$job->getName().'"'."\n";
    } else {
        echo 'Got event "'.$event->getName().'"'."\n";
    }

    if ($event->getName() == \deploydog\Slavedriver\Slavedriver::EVENT_JOB_OUTPUT_STDOUT){
        echo 'stdOut > ' . $event->getParam('stdOut')."\n";
    } else if ($event->getName() == \deploydog\Slavedriver\Slavedriver::EVENT_JOB_OUTPUT_STDERR){
        echo 'stdErr > ' . $event->getParam('stdErr')."\n";
    }
});

Slavedriver itself started (should be roughly every 1 minute)

• Event: slavedriver.started
• Event constant: Slavedriver::EVENT_SLAVEDRIVER_STARTED
• Event target: None
• Event params: None

Job started

• Event: slavedriver.job.started
• Event constant: Slavedriver::EVENT_JOB_STARTED
• Event target: The Job object
• Event params: None

Job finished successfully

• Event: slavedriver.job.finished.success
• Event constant: Slavedriver::EVENT_JOB_FINISHED_SUCCESS
• Event target: The Job object
• Event params: None

Job finished with error (based on exit code)

• Event: slavedriver.job.finished.error
• Event constant: Slavedriver::EVENT_JOB_FINISHED_ERROR
• Event target: The Job object
• Event params:
  • exitCode = The exit code of the command

Job stdOut data (this is called every few seconds with additional data)

• Event: slavedriver.job.output.stdout
• Event constant: Slavedriver::EVENT_JOB_OUTPUT_STDOUT
• Event target: The Job object
• Event params:
  • stdOut = The stdOut data since the last trigger of this event

Job stdErr data (this is called every few seconds with additional data)

• Event: slavedriver.job.output.stderr
• Event constant: Slavedriver::EVENT_JOB_OUTPUT_STDERR
• Event target: The Job object
• Event params:
  • stdErr = The stdErr data since the last trigger of this event

Job was still running when the timeout value was hit (and it will have been killed)

• Event: slavedriver.job.timeout
• Event constant: Slavedriver::EVENT_JOB_TIMEOUT
• Event target: The Job object
• Event params: None

Job should have been started but the last instance was still running and they cannot overlap

• Event: slavedriver.job.last_instance_still_running
• Event constant: Slavedriver::EVENT_JOB_LAST_INSTANCE_STILL_RUNNING
• Event target: The Job object
• Event params: None

Job still running but expected runtime has elapsed (job not killed)

• Event: slavedriver.job.expected_runtime_elapsed
• Event constant: Slavedriver::EVENT_JOB_EXPECTED_RUNTIME_ELAPSED
• Event target: The Job object
• Event params: None

Logging

Logging is provided by any PSR-3 compatible logger. You can provider custom log levels for different messages if you wish, or leave the leave the log levels at the defaults which are sensible. To setup logging, call the setLogger() method on the Slavedriver object, passing in the PSR-3 logger and optionally the log levels.

$logger = new \Monolog\Logger('Slavedriver');
$logger->pushHandler(new \Monolog\Handler\StreamHandler(__DIR__.'/slavedriver.log'));

$slavedriver->setLogger($logger);

Or with custom log levels (e.g. override the ErrorExitCode log level to alert)

$logLevels = new \deploydog\Slavedriver\LogLevels();
$logLevels->setErrorExitCode(\Psr\Log\LogLevel::ALERT);

$slavedriver->setLogger($logger, $logLevels);

Exceptions

All exceptions thrown by Slavedriver extend the base Slavedriver exception deploydog\Slavedriver\Exception\Slavedriver which extends the base PHP exception \Exception. Different Slavedriver exceptions are thrown for different reasons, for example InvalidJob and InvalidSlavedriverConfig. Check the Exceptions directory for the possible options.