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Kala

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Kala is a simplistic, modern, and performant job scheduler written in Go. Features:

Single binary
No dependencies
JSON over HTTP API
Job Stats
Configurable Retries
Scheduling with ISO 8601 Date and Interval notation
Dependent Jobs
Persistent with several database drivers
Web UI

Note that it is not battle-tested. Use at your own risk.

Kala was inspired by the desire for a simpler Chronos (developed by Airbnb). Kala is Chronos for the rest of us.

If you need fault tolerance, distributed features, massive scale, then I recommend checking out Chronos. This is designed to be the Chronos for start-ups.

Installing Kala

Kala uses Go Modules

Get Kala
```
go get github.com/ajvb/kala
```
Run Kala
```
kala serve
```

Getting Started

Once you have installed Kala onto the machine you would like to use, you can follow the below steps to start using it.

To run Kala as a server:

$ kala serve
INFO[0000] Preparing cache
INFO[0000] Starting server on port :8000

$ kala serve -p 2222
INFO[0000] Preparing cache
INFO[0000] Starting server on port :2222

Kala uses BoltDB by default for the job database by using jobdb and boltpath params:

kala serve --jobdb=boltdb --boltpath=/path/to/dir

use Redis by using the jobdb, jobdb-address and jobdb-password params:

kala serve --jobdb=redis --jobdb-address=127.0.0.1:6379 --jobdb-password=password

use Consul by using the jobdb and jobdb-address params:

kala serve --jobdb=consul --jobdb-address=127.0.0.1:8500

use Mongo by using the jobdb, jobdb-address, jobdb-username, and jobdb-password params:

kala serve --jobdb=mongo --jobdb-address=server1.example.com,server2.example.com --jobdb-username=admin --jobdb-password=password

use Postgres by using the jobdb, jobdb-address params:

kala serve --jobdb=postgres --jobdb-address=server1.example.com/kala --jobdb-username=admin --jobdb-password=password

use MariaDB, MySQL by using the jobdb, jobdb-address, jobdb-tls-capath, jobdb-tls-certpath, jobdb-tls-keypath, jobdb-tls-servername params:

kala serve --jobdb=mariadb --jobdb-address=(server1.example.com)/kala --jobdb-username=admin --jobdb-password=password

kala serve --jobdb=mysql --jobdb-address="tcp(server1.example.com:3306)/kala?tls=custom" --jobdb-username=admin --jobdb-password=password --jobdb-tls-capath=/path/to/server-ca.pem --jobdb-tls-certpath=/path/to/client-cert.pem --jobdb-tls-keypath=/path/to/client-key.pem --jobdb-tls-servername=server1.example.com

Kala runs on 127.0.0.1:8000 by default. You can easily test it out by curling the metrics path.

$ curl http://127.0.0.1:8000/api/v1/stats/
{"Stats":{"ActiveJobs":2,"DisabledJobs":0,"Jobs":2,"ErrorCount":0,"SuccessCount":0,"NextRunAt":"2015-06-04T19:25:16.82873873-07:00","LastAttemptedRun":"0001-01-01T00:00:00Z","CreatedAt":"2015-06-03T19:58:21.433668791-07:00"}}

Once it's up in running, you can utilize curl or the official go client to interact with Kala. Also check out the examples directory.

Examples of Usage

There are more examples in the examples directory within this repo. Currently its pretty messy. Feel free to submit a new example if you have one.

Deployment

Supervisord

After installing supervisord, open its config file (/etc/supervisor/supervisord.conf is the default usually) and add something like:

[program:kala]
command=kala serve
autorestart=true
stdout_logfile=/var/log/kala.stdout.log
stderr_logfile=/var/log/kala.stderr.log

Docker

If you have docker installed, you can build the dockerfile in this directory with docker build -t kala . and run it as a daemon with: docker run -it -d -p 8000:8000 kala

API v1 Docs

All routes have a prefix of /api/v1

Client Libraries

Official:

Go - Docs: http://godoc.org/github.com/ajvb/kala/client
```
go get github.com/ajvb/kala/client
```

Contrib:

Node.js
```
npm install kala-node
```

Python

pip install git+https://github.com/dmajere/kala-python.git

Job Data Struct

Docs can be found here

Things to Note

If schedule is omitted, the job will run immediately.

Job JSON Example

{
        "name":"test_job",
        "id":"93b65499-b211-49ce-57e0-19e735cc5abd",
        "command":"bash /home/ajvb/gocode/src/github.com/ajvb/kala/examples/example-kala-commands/example-command.sh",
        "owner":"",
        "disabled":false,
        "dependent_jobs":null,
        "parent_jobs":null,
        "schedule":"R2/2015-06-04T19:25:16.828696-07:00/PT10S",
        "retries":0,
        "epsilon":"PT5S",
        "success_count":0,
        "last_success":"0001-01-01T00:00:00Z",
        "error_count":0,
        "last_error":"0001-01-01T00:00:00Z",
        "last_attempted_run":"0001-01-01T00:00:00Z",
        "next_run_at":"2015-06-04T19:25:16.828794572-07:00"
}

Breakdown of schedule string. (ISO 8601 Notation)

Example schedule string:

R2/2017-06-04T19:25:16.828696-07:00/PT10S

This string can be split into three parts:

Number of times to repeat/Start Datetime/Interval Between Runs

Number of times to repeat

This is designated with a number, prefixed with an R. Leave out the number if it should repeat forever.

Examples:

R - Will repeat forever
R1 - Will repeat once
R231 - Will repeat 231 times.

Start Datetime

This is the datetime for the first time the job should run.

Kala will return an error if the start datetime has already passed.

Examples:

2017-06-04T19:25:16
2017-06-04T19:25:16.828696
2017-06-04T19:25:16.828696-07:00
2017-06-04T19:25:16-07:00

To Note: It is recommended to include a timezone within your schedule parameter.

Interval Between Runs

This is defined by the ISO8601 Interval Notation.

It starts with a P, then you can specify years, months, or days, then a T, preceded by hours, minutes, and seconds.

Lets break down a long interval: P1Y2M10DT2H30M15S

P - Starts the notation
1Y - One year
2M - Two months
10D - Ten days
T - Starts the time second
2H - Two hours
30M - Thirty minutes
15S - Fifteen seconds

Now, there is one alternative. You can optionally use just weeks. When you use the week operator, you only get that. An example of using the week operator for an interval of every two weeks is P2W.

Examples:

P1DT1M - Interval of one day and one minute
P1W - Interval of one week
PT1H - Interval of one hour.

More Information on ISO8601

Wikipedia's Article

Overview of routes

Task	Method	Route
Creating a Job	POST	/api/v1/job/
Getting a list of all Jobs	GET	/api/v1/job/
Getting a Job	GET	/api/v1/job/{id}/
Deleting a Job	DELETE	/api/v1/job/{id}/
Deleting all Jobs	DELETE	/api/v1/job/all/
Getting metrics about a certain Job	GET	/api/v1/job/stats/{id}/
Starting a Job manually	POST	/api/v1/job/start/{id}/
Disabling a Job	POST	/api/v1/job/disable/{id}/
Enabling a Job	POST	/api/v1/job/enable/{id}/
Getting app-level metrics	GET	/api/v1/stats/

/job

This route accepts both a GET and a POST. Performing a GET request will return a list of all currently running jobs. Performing a POST (with the correct JSON) will create a new Job.

Note: When creating a Job, the only fields that are required are the Name and the Command field. But, if you omit the Schedule field, the job will be ran immediately.

Example:

$ curl http://127.0.0.1:8000/api/v1/job/
{"jobs":{}}
$ curl http://127.0.0.1:8000/api/v1/job/ -d '{"epsilon": "PT5S", "command": "bash /home/ajvb/gocode/src/github.com/ajvb/kala/examples/example-kala-commands/example-command.sh", "name": "test_job", "schedule": "R2/2017-06-04T19:25:16.828696-07:00/PT10S"}'
{"id":"93b65499-b211-49ce-57e0-19e735cc5abd"}
$ curl http://127.0.0.1:8000/api/v1/job/
{
    "jobs":{
        "93b65499-b211-49ce-57e0-19e735cc5abd":{
            "name":"test_job",
            "id":"93b65499-b211-49ce-57e0-19e735cc5abd",
            "command":"bash /home/ajvb/gocode/src/github.com/ajvb/kala/examples/example-kala-commands/example-command.sh",
            "owner":"",
            "disabled":false,
            "dependent_jobs":null,
            "parent_jobs":null,
            "schedule":"R2/2017-06-04T19:25:16.828696-07:00/PT10S",
            "retries":0,
            "epsilon":"PT5S",
            "success_count":0,
            "last_success":"0001-01-01T00:00:00Z",
            "error_count":0,
            "last_error":"0001-01-01T00:00:00Z",
            "last_attempted_run":"0001-01-01T00:00:00Z",
            "next_run_at":"2017-06-04T19:25:16.828794572-07:00"
        }
    }
}

/job/{id}

This route accepts both a GET and a DELETE, and is based off of the id of the Job. Performing a GET request will return a full JSON object describing the Job. Performing a DELETE will delete the Job.

Example:

$ curl http://127.0.0.1:8000/api/v1/job/93b65499-b211-49ce-57e0-19e735cc5abd/
{"job":{"name":"test_job","id":"93b65499-b211-49ce-57e0-19e735cc5abd","command":"bash /home/ajvb/gocode/src/github.com/ajvb/kala/examples/example-kala-commands/example-command.sh","owner":"","disabled":false,"dependent_jobs":null,"parent_jobs":null,"schedule":"R2/2017-06-04T19:25:16.828696-07:00/PT10S","retries":0,"epsilon":"PT5S","success_count":0,"last_success":"0001-01-01T00:00:00Z","error_count":0,"last_error":"0001-01-01T00:00:00Z","last_attempted_run":"0001-01-01T00:00:00Z","next_run_at":"2017-06-04T19:25:16.828737931-07:00"}}
$ curl http://127.0.0.1:8000/api/v1/job/93b65499-b211-49ce-57e0-19e735cc5abd/ -X DELETE
$ curl http://127.0.0.1:8000/api/v1/job/93b65499-b211-49ce-57e0-19e735cc5abd/

/job/stats/{id}

Example:

$ curl http://127.0.0.1:8000/api/v1/job/stats/5d5be920-c716-4c99-60e1-055cad95b40f/
{"job_stats":[{"JobId":"5d5be920-c716-4c99-60e1-055cad95b40f","RanAt":"2017-06-03T20:01:53.232919459-07:00","NumberOfRetries":0,"Success":true,"ExecutionDuration":4529133}]}

/job/start/{id}

Example:

$ curl http://127.0.0.1:8000/api/v1/job/start/5d5be920-c716-4c99-60e1-055cad95b40f/ -X POST

/job/disable/{id}

Example:

$ curl http://127.0.0.1:8000/api/v1/job/disable/5d5be920-c716-4c99-60e1-055cad95b40f/ -X POST

/job/enable/{id}

Example:

$ curl http://127.0.0.1:8000/api/v1/job/enable/5d5be920-c716-4c99-60e1-055cad95b40f/ -X POST

/stats

Example:

$ curl http://127.0.0.1:8000/api/v1/stats/
{"Stats":{"ActiveJobs":2,"DisabledJobs":0,"Jobs":2,"ErrorCount":0,"SuccessCount":0,"NextRunAt":"2017-06-04T19:25:16.82873873-07:00","LastAttemptedRun":"0001-01-01T00:00:00Z","CreatedAt":"2017-06-03T19:58:21.433668791-07:00"}}

Debugging Jobs

There is a command within Kala called run which will immediately run a command as Kala would run it live, and then gives you a response on whether it was successful or not. Allows for easier and quicker debugging of commands.

$ kala run "ruby /home/user/ruby/my_ruby_script.rb"
Command Succeeded!
$ kala run "ruby /home/user/other_dir/broken_script.rb"
FATA[0000] Command Failed with err: exit status 1

Dependent Jobs

How to add a dependent job

Check out this example for how to add dependent jobs within a python script.

Notes on Dependent Jobs

Dependent jobs follow a rule of First In First Out
A child will always have to wait until a parent job finishes before it runs
A child will not run if its parent job does not.
If a child job is disabled, it's parent job will still run, but it will not.
If a child job is deleted, it's parent job will continue to stay around.
If a parent job is deleted, unless its child jobs have another parent, they will be deleted as well.

Original Contributors and Contact

Original Author and Core Maintainer:

AJ Bahnken / @ajvbahnken / aj@ajvb.me

Original Reviewers:

Sam Dolan / @samdolan
Steve Phillips / @elimisteve

Awesome

Kala

Installing Kala

Getting Started

Examples of Usage

Deployment

Supervisord

Docker

API v1 Docs

Client Libraries

Official:

Contrib:

Job Data Struct

Things to Note

Job JSON Example

Breakdown of schedule string. (ISO 8601 Notation)

Number of times to repeat

Start Datetime

Interval Between Runs

More Information on ISO8601

Overview of routes

/job

/job/{id}

/job/stats/{id}

/job/start/{id}

/job/disable/{id}

/job/enable/{id}

/stats

Debugging Jobs

Dependent Jobs

How to add a dependent job

Notes on Dependent Jobs

Original Contributors and Contact

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