Cronjobs

The main purpose of cronjobs is to enable running a certain task on a regular schedule. This could be anywhere from a small script to, for example do an API call, to complex batch jobs with multiple tasks running at the same time.

Cronjob resources represent a group of tasks (or replicas or instances, all three terms will be used interchangeably) that run a docker image configured as defined in the cronjob resource definition file.

These tasks will be started following the configured schedule and won't be automatically restarted when they finish running. If a task is already running when the next iteration is scheduled to run, the existing tasks will be left running and no new tasks will be started.

Updatability

Cronjob resources can be updated.

The update will trigger a pull of the defined docker image and then will stop any tasks running, until the next schedule trigger.

Basic creation

Consider the following cronjob resource definition file:

# my-cronjob.yaml
account_id: 43
type: cronjob
name: test
image: backup-database:latest
cpu: 1
memory: 100m
enabled: true
schedule: '@weekly'

We can create the cronjob by executing the command bellow:

$ vinfra resource create -f my-cronjob.yaml
account_id: 43
type: cronjob
name: test
image: backup-database:latest
cpu: 1
memory: 100m
enabled: true
schedule: '@weekly'

Advanced usage

In addition to the required attributes defined in the example above, a cronjob can be configured even further by setting the non-required attributes.

enabled

When enabled is set to false the cronjob won't be started. This allows to have the cronjobs created but only enable them when needed.

schedule

A crontab expression. Must follow the CRON expression format

command

command is a list of strings, by default empty. These are the arguments that will be passed to the docker image in the same way they are passed when doing docker run <image> <command>.

args

args is a list of strings, by default empty. These are the arguments that will be passed to the docker image in the same way they are passed when doing docker run <image> <command> <args...>.

environment

environment is a mapping that defines the environment variables that will be injected to the cronjob tasks.

networks

networks is a list of network resource ids. This defines the networks that the instances of the service will be connected to.

replicas

replicas defines the number of tasks that the service will be running. Defaults to 1.

secrets

secrets is a list of secrets resource ids. This defines the secrets that the instances of the service will have access to.