Sometimes I need to run some periodical tasks and get reports. Strait on my machine. Something simple and configurable. And yeah, sometimes I want to run task remotely, not only on localhost, over ssh or on docker instances.

Linux provides old good cron for that. However if tasks are not just small scripts crontab quickly becomes awkward solution and is hard to maintain. There are "heavy" tools like Jenkins or Team City, but it seems overkill for "one-machine" purpose. I need something light, quick to deploy and hack-able.

Let me introduce small, but flexible cron jobs runner called - Sparky.

The essential features of Sparky:

• Defining jobs times in crontab style
• Scenarios defined as Sparrowdo scripts
• Nice set of predefined tasks is available
• Everything is kept in SCM repository - easy to port, maintain and track changes
• Tasks gets run asynchronously in one of 3 flavours - 1) on localhost 2) on remote machines via ssh 3) on docker instances
• Nice web UI to read tasks reports is provided

Interested? Let's go ahead! (:

Install

Sparky is written on Perl6, so install as Perl6 module, we want the lates GH version:

$ git clone Sparky https://github.com/melezhik/sparky.git
$ cd sparky
$ zef install .

Initialization

Sparky stores it's data in database, the default one is sqlite ( mysql/postgrsql are also possible ), we need create a schema:

$ perl6 db-init.pl6

Now let's run sparky services, the first one is called sparky-web is for UI application and second one called sparkyd is daemon to run tasks

The easiest way to do so is using Sparrowdo systemd installers come with distribution:

$ sparrowdo --sparrowfile=utils/install-sparkyd-systemd.pl6 --local_mode
$ sparrowdo --sparrowfile=utils/install-sparky-web-systemd.pl6 --local_mode

If everything is ok we will see Sparky UI available at http://localhost:3000 and sparkyd daemon seen as a process in the process list:

$ ps uax | grep sparkyd
root       9511  3.3 10.0 574440 202988 ?       Ssl  14:38   7:35 /opt/rakudo-pkg/bin/moar --execname=/opt/rakudo-pkg/bin//perl6 --libpath=/opt/rakudo-pkg/share/nqp/lib --libpath=/opt/rakudo-pkg/share/nqp/lib --libpath=/opt/rakudo-pkg/share/perl6/lib --libpath=/opt/rakudo-pkg/share/perl6/runtime /opt/rakudo-pkg/share/perl6/runtime/perl6.moarvm /opt/rakudo-pkg/share/perl6/site/bin/sparkyd --root=/root/projects/devops/sparky

Now the most exciting part - setting up the first task, run it and see the results!

Sparky task

As has been sain, Sparky task is just a Sparrowdo scenario, if you're not familiar with Saprrowdo - don't worry there are a plenty of posts about this tool. But for us is just a handy DSL to create users scenarios:

$ nano project1/sparrowfile

#!perl6

bash "echo Hello! My name is Sparky!";

This is simple task is ready to get run with Sparky, but first we need to set up crontab entry, it's easy, it's just a good old crontab style:

$ nano project1/sparky.yaml

# what about running every minute? 
crontab: "* * * * *"

I have not said that, but we should keep 2 files (sparrowfile and sparky.yaml) in some directory located in $SPARKY_ROOT directory which is ~/.sparky/projects by default:

$ ls -d ~/.sparky/projects
project1
project2
project3

So sparkyd reads all the sub-directories ( 1 level depth ) located at $SPARKE_ROOT and executes found sparky tasks. The $SPARKE_ROOT is configurable through environmental variable or as a command line option for sparky task runner daemon:

$ sparkyd --root=/path/to/sparky/root/directory

Ok, let's go to WEB UI to see the results for our first task:

running sparrow tasks on 127.0.0.1 ... 

target OS is - centos7
push [task] run bash: echo 'Hello! My name is Sparky!' ... OK
SPL file /opt/sparky-sparrowdo/project1/sparrow.list is empty
set up task box file - /home/melezhik/.sparrowdo//opt/sparky-sparrowdo/project1/task-box.json - OK

found ini file: /home/melezhik/sparrowdo.ini
sparrow root: [/opt/sparky-sparrowdo/project1]
/opt/sparky-sparrowdo/project1/sparrow.index updated OK from https://sparrowhub.org
sparrow root: [/opt/sparky-sparrowdo/project1]
public@bash is uptodate (0.1.8)
running task box from /opt/sparky-sparrowdo/project1/sparrow-cache/task-box.json ... 
@ runs bash command
2018-10-19 19:25:01 : [task] run bash: echo Hello! [path] /modules/bash-command/ [params] envvars:
Hello! My name is Sparky!
ok  scenario succeeded
STATUS  SUCCEED

So, as we can see task is successful completed, so far we run task on localhost, but we are not limited. Sparkly is also capable ran tasks remotely:

Over ssh

$ nano sparky.yaml

sparrowdo:
  host: '192.168.0.1'
  ssh_private_key: /path/to/ssh_private/key.pem
  ssh_user: sparky

On Docker

$ nano sparky.yaml

sparrowdo:
  docker: 'black_horse'

What I've not said:

Just highlights of that's not been cover through this post

• Sparky plugins to extend basic functionality ( sending notification email upon tasks finish and so on )

• Configuring Sparky tasks

• Managing old reports

• Disabling tasks

• Using mysql/postgresql database engines

• Debugging Sparky tasks using task runner.

• Docker image with Sparky ready to use

As always your comments and feedback is highly appreciated.