Dockerized Jobber Cron

Supported tags and respective Dockerfile links

Make It Short!

In short, you can define periodic tasks for an arbitrary number of jobs.

Example:

$ docker run -d \
    --name jobber \
    -e "JOB_NAME1=TestEcho" \
    -e "JOB_COMMAND1=echo hello world" \
    blacklabelops/jobber

How It Works

The environment variables are numerated. Just add the number behind the environment variable and the container will create a job definition for Jobber!

This way the container can handle an arbitrary number of jobs without file handling or cumbersome syntax!

Example with two tasks:

$ docker run -d \
    --name jobber \
    -e "JOB_NAME1=TestEcho" \
    -e "JOB_COMMAND1=echo hello world" \
    -e "JOB_NAME2=TestEcho" \
    -e "JOB_COMMAND2=echo hello moon" \
    blacklabelops/jobber

Environment Variables

Globally, there is a notify program defined, default one is sendmail, you can override it using an environment variable, JOBS_NOTIFY_CMD.
This program will receive a JSON payload as specified in the jobber docs⁠

Every job definition is specified by up to four environment variables:

• JOB_NAME: The identifier for the job, must not contain empty spaces!
• JOB_COMMAND: The bash command to be executed.
• JOB_TIME: The cron schedule for the job. See Documentation⁠
• JOB_ON_ERROR: How Jobber should act on errors. Values: Stop, Backoff, Continue (Default). See Documentation⁠
• JOB_NOTIFY_ERR: If Jobber should notify on error. Values: true, false. Default is false
• JOB_NOTIFY_FAIL: If Jobber should notify on failure. Values: true, false. Default is false

Full example:

$ docker run -d \
    --name jobber \
    -e "JOBS_NOTIFY_CMD=/bin/bash" \
    -e "JOB_NAME1=TestEcho" \
    -e "JOB_COMMAND1=echo hello world" \
    -e "JOB_TIME1=1" \
    -e "JOB_ON_ERROR1=Backoff" \
    -e "JOB_NOTIFY_ERR1=true" \
    -e "JOB_NOTIFY_FAIL1=true" \
    blacklabelops/jobber

The Cron Time

When it comes to the cron string then Jobber is a little bit different. If you do not define any time then the resulting cron table will be

* * * * * *

and the job will be executed every second.

You can also define just one number "1". This will be interpreted as

1 * * * * *

Example:

$ docker run \
    --name jobber \
    -e "JOB_NAME1=TestEcho" \
    -e "JOB_COMMAND1=echo hello world" \
    -e "JOB_TIME1=1 * * * * *"
    blacklabelops/jobber

so you can see that you have to specify the time string from the back and the rest will be filled up by Jobber.

As a reminder, cron timetable is like follows:

1. Token: Second
2. Token: Minute
3. Token: Hour
4. Token: Day of Month
5. Token: Month
6. Token: Day of Week

Vagrant

Vagrant is fabulous tool for pulling and spinning up virtual machines like docker with containers. I can configure my development and test environment and simply pull it online. And so can you! Install Vagrant and Virtualbox and spin it up. Change into the project folder and build the project on the spot!

$ vagrant up
$ vagrant ssh
[vagrant@localhost ~]$ cd /vagrant
[vagrant@localhost ~]$ docker-compose up

Vagrant does not leave any docker artifacts on your beloved desktop and the vagrant image can simply be destroyed and repulled if anything goes wrong. Test my project to your heart's content!

First install:

• Vagrant⁠
• Virtualbox⁠

Support

Leave a message and ask questions on Hipchat: blacklabelops/hipchat⁠

References

• Jobber⁠
• Docker Homepage⁠
• Docker Userguide⁠