Introduction

Pipelines are typically triggered actively, such as through Git operations, page interactions, or API calls. They can also be configured as scheduled tasks to run at specified times.

Adding Scheduled Tasks

Below is an example configuration of a scheduled task pipeline.

.cnb.yml

# Scheduled task pipeline configuration on the main branch
# When the scheduled task is triggered, it fetches the code from the main branch for building
main:
  # User A submits the scheduled task pipeline configuration, with A as the triggerer when the scheduled task is triggered
  "crontab: 30 5,17 * * *": # Scheduled task triggers according to the configured time
    - name: crontab-a
      stages:
        - name: test
          script: echo 1

Configuration Breakdown

This section will explain in detail the format and meaning of each part of the scheduled pipeline configuration.

main

Similar to regular pipelines, you can specify an existing branch in the repository. This indicates the code to be used when the scheduled task is executed. For example, if set to main, the code at the HEAD of the main branch will be used when the pipeline runs.

To improve resource utilization, scheduled task branch names do not support glob expressions and must be explicit branch names.

crontab: 30 5,17 * * *

In contrast to other pipelines triggered by specific events like push, web_trigger, or api_trigger, scheduled tasks are triggered based on a cron rule. The format for specifying the trigger time is crontab: ${CRON}.

• crontab: is a fixed prefix for scheduled pipeline events.
• ${CRON} represents the actual execution time in standard POSIX cron syntax.

For example, the above configuration will trigger execution twice daily at 5:30 and 17:30 in the Asia/Shanghai time zone.

When a scheduled task pipeline runs, the person responsible for the scheduled task configuration (addition or modification) is considered the triggerer of the pipeline.

To provide a more reliable service, we restrict the minimum time interval for scheduled tasks to 5 minutes. Scheduled tasks with intervals less than 5 minutes (e.g., * * * * *) cannot be successfully added.

Modifying Scheduled Tasks

Modifying a scheduled task configuration involves changing three main parts:

• Trigger time: e.g., 30 5,17 * * * -> 0 9 * * *, changing the trigger time.
• Pipeline configuration: modifying stages and env contents, etc.
• Responsible person: changing the operator of the scheduled task, who is considered the triggerer of the pipeline when the scheduled task runs.

.cnb.yml

main:
  # User B updated the scheduled task pipeline configuration, with B as the triggerer when the scheduled task is triggered
  "crontab: 30 5,17 * * *": # Modified the execution time, scheduled task triggers according to the new time
    - name: crontab-b
      stages:
        - name: test
          script: echo 2

If the person responsible for a scheduled task is removed from the repository, the scheduled task pipeline will fail. You can update the responsible person by modifying the scheduled task configuration and pushing it again.

Deleting Scheduled Tasks

Editing the pipeline configuration file under a branch to correspond to a different cron expression effectively deletes the original scheduled task and adds a new one. If there are no cron expressions in the pipeline configuration file, it means all scheduled tasks under that branch are deleted.

.cnb.yml

main:
  # Deleted the scheduled task mentioned earlier

When a remote repository branch is deleted, all scheduled tasks under that branch are also deleted. Repository deletion removes all scheduled tasks within it.

Comparison

Using a push event as an example, the table below compares scheduled tasks and push events, helping you understand the differences between the two.

Feature	Scheduled Tasks	Push Events
Trigger	Based on time cron rule	Triggered by specific operations (e.g., code push)
Branch Config	Uses explicit branch names	Supports glob expressions for branch names
Responsible Person	Triggered by the task configurator	Triggered by the event initiator
Minimum Interval	Minimum interval for task scheduling is 5 minutes	No specific minimum interval requirement
Modification	Modify trigger time, pipeline configuration, responsible person	Directly modify pipeline configuration
Deletion	Modify cron expression to delete or add tasks	Deleting pipeline configuration removes the pipeline