nextkala

NextKala

NextKala is a fork of kala.

NextKala is a simplistic, modern, and performant job scheduler written in Go. It is an improved version of Kala.

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
• OAuth2 support (to be implemented)
• May be deployed in a highly available cluster (to be implemented)

Installing NextKala

NextKala uses Go Modules

1. Get NextKala

   go get github.com/nextiva/nextkala
   

2. Run NextKala

   nextkala serve
   

Getting Started

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

To run NextKala as a server:

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

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

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

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

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

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

NextKala 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:nextkala]
command=nextkala serve
autorestart=true
stdout_logfile=/var/log/nextkala.stdout.log
stderr_logfile=/var/log/nextkala.stderr.log

Docker

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

API v1 Docs

All routes have a prefix of /api/v1

Client Libraries

Official:

• Go - Docs: http://godoc.org/github.com/nextiva/nextkala/client

  go get github.com/nextiva/nextkala/client
  

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/nextiva/nextkala/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

/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 ~/go/src/github.com/nextiva/nextkala/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"}

$ cat create_remote.json
{
  "name":"Run Advice",
  "type":1,
  "owner":"dlynn@nextiva.com",
  "schedule":"R2/2020-11-20T15:35:16.828696-07:00/PT60S",
  "retries":0,
  "remote_properties": {
    "url":"https://slipf-18.com/runcoach/v1/raceStrategy",
    "method":"GET",
    "headers": {"charset": ["UTF-8"], "Authorization": ["my voice is my password.  authorize me."]},
    "timeout":0,
    "expected_response_codes":[200]
  }
}

$ curl http://127.0.0.1:8000/api/v1/job/ -d @create_remote.json
{"id":"31bd5533-f0a3-41d7-408d-9650f390b82d"}

$ 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 ~/go/src/github.com/nextiva/nextkala/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/nextiva/nextkala/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.

$ nextkala run "ruby /home/user/ruby/my_ruby_script.rb"
Command Succeeded!
$ nextkala 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.