This tutorial shows how to create a scheduled job using Chronos. We’re going to create a job that runs every 10 seconds and prints the current date.
- Data Infrastructure Engineers
- Data Scientists
- Devops Engineers
- Install Chronos
- The job needs at least 128MB of RAM and 0.1 CPU cores available in the cluster.
From the DC/OS web interface, go to the Services tab and click on Chronos to open its web UI.
In the Chronos UI, click the New Job link to bring up the form for creating jobs.
Fill in the following values:
- NAME: “Date”
- DESCRIPTION: “Prints the current date”
- COMMAND: “/bin/date”
- OWNER(S): Enter your email address.
- SCHEDULE: Enter “T10S” in the “P” field
Chronos uses ISO 8601 Interval Notation to describe job schedules. “T10S” means run this job every 10 seconds. For details, see the ISO 8601 Wikipedia article.
Click the Create button at the top to submit the job to Chronos.
Let’s verify that our job ran successfully. Run the following CLI command to view all completed tasks:
dcos task --completed ct*
--completedargument includes tasks that have completed their execution. Chronos uses the prefix
ctfor all its tasks, so
ct*filters only Chronos tasks.
The output should look similar to this:
NAME HOST USER STATE ID ChronosTask:Date 10.0.0.252 root F ct:1460844479000:0:Date: ChronosTask:Date 10.0.0.252 root F ct:1460844559000:0:Date: ChronosTask:Date 10.0.0.252 root F ct:1460844569000:0:Date:
To view the output of a task, copy one of the values under the
IDcolumn in the output of the previous command, and use it as the argument to
dcos task log:
dcos task log --completed ct:1460844479000:0:Date:
The output should look similar to this, and include a line with the current date:
Registered executor on 10.0.0.252 Starting task ct:1460844479000:0:Date: Forked command at 15344 sh -c '/bin/date' Sat Apr 16 22:07:59 UTC 2016 Command exited with status 0 (pid: 15344)