Principle:Testtimescaling Testtimescaling github io Scheduled CI Trigger

Metadata
Page Type	Principle
Concept Type	External Tool
Domain	CI_CD, Automation
Namespace	Testtimescaling_Testtimescaling_github_io
Workflow	Automated_Citation_Tracking
Date Created	2026-02-14
Implementation	Implementation:Testtimescaling_Testtimescaling_github_io_GitHub_Actions_Cron_Schedule
Source	GitHub Actions Schedule

Overview

Cron-based scheduling for CI/CD pipelines enables time-based triggers that run workflows at fixed intervals without human intervention.

Description

Scheduled CI triggers allow development teams to automate recurring tasks by defining time-based rules that initiate CI/CD pipeline runs. Rather than relying on code pushes, pull requests, or manual dispatch, a scheduled trigger fires at predetermined intervals governed by a cron expression. This is particularly useful for tasks that must run periodically regardless of code changes, such as fetching external data, regenerating reports, refreshing caches, or performing routine maintenance.

The scheduling mechanism is provided by the CI/CD platform itself (e.g., GitHub Actions, GitLab CI, Jenkins) and operates on the platform's infrastructure. The workflow definition declares the schedule alongside any other trigger events, allowing the same pipeline to be invoked both on a timer and through manual or event-driven means.

Usage

Use scheduled CI triggers when you need:

• Periodic automated tasks -- such as daily data fetching from external APIs, weekly report generation, or hourly cache refreshes.
• Decoupled execution -- tasks that must run independently of code changes or developer activity.
• Predictable timing -- operations that need to execute at specific times (e.g., midnight UTC to minimize API rate limit contention).
• Complementary manual triggers -- combining scheduled runs with manual dispatch (e.g., workflow_dispatch) to allow on-demand execution when needed.

Theoretical Basis

The cron expression syntax is the foundation of time-based scheduling in Unix-like systems and has been widely adopted by CI/CD platforms. A standard cron expression consists of five fields, each representing a unit of time:

Field	Allowed Values	Description
Minute	0-59	The minute of the hour at which the job runs
Hour	0-23	The hour of the day (24-hour format, UTC in most CI systems)
Day of Month	1-31	The day of the month
Month	1-12	The month of the year
Day of Week	0-6 (Sunday=0)	The day of the week

Special characters include:

• * -- matches any value in the field (wildcard).
• , -- separates multiple specific values (e.g., 1,15 for the 1st and 15th).
• - -- defines a range (e.g., 1-5 for Monday through Friday).
• / -- defines a step value (e.g., */15 for every 15 units).

Example expressions:

• 0 0 * * * -- Every day at midnight UTC.
• 30 6 * * 1-5 -- Every weekday at 06:30 UTC.
• 0 */4 * * * -- Every 4 hours.
• 0 0 1 * * -- First day of every month at midnight.

The abstraction of cron-based scheduling decouples when a task runs from what the task does. The CI/CD platform's scheduler evaluates the cron expression against the current time and enqueues a workflow run when the expression matches. This follows the principle of separation of concerns: the scheduling logic is declarative and external to the workflow steps themselves.

Note: Most CI/CD platforms (including GitHub Actions) evaluate cron schedules in UTC and may have slight delays during periods of high demand. Scheduled workflows run on the default or base branch of the repository.

Related Pages

• Implementation:Testtimescaling_Testtimescaling_github_io_GitHub_Actions_Cron_Schedule
• Principle:Testtimescaling_Testtimescaling_github_io_Repository_Checkout -- The next step after the schedule triggers the workflow
• Principle:Testtimescaling_Testtimescaling_github_io_Automated_Git_Commit -- The final step that persists results back to the repository