Scheduled Tasks

Crontab Time Expression

Time Expression Format

gocron uses Linux-crontab time expression syntax and supports second-level task definition.

Format: second minute hour day month week

Expression Examples

1 * * * * *           # Run at the first second of every minute
*/20 * * * * *        # Run every 20 seconds
0 30 21 * * *         # Run once every day at 21:30:00
0 0 23 * * 6          # Run once every Saturday at 23:00:00

Shortcut Syntax

gocron supports the following shortcut syntax:

Shortcut	Description	Equivalent Expression
@yearly	Run once a year	0 0 0 1 1 *
@monthly	Run once a month	0 0 0 1 * *
@weekly	Run once a week	0 0 0 * * 0
@daily	Run once a day	0 0 0 * * *
@midnight	Run once at midnight every day	0 0 0 * * *
@hourly	Run once an hour	0 0 * * * *
@every 30s	Run every 30 seconds	-
@every 1m20s	Run every 1 minute and 20 seconds	-
@every 3h5m10s	Run every 3 hours, 5 minutes and 10 seconds	-

Execution Methods

gocron supports two task execution methods:

1. Shell Command

Execute shell commands on remote host.

Examples:

ps aux | grep gocron
cd /tmp && ls -la
echo "Hello, gocron!" > /tmp/test.txt

Note

Shell task execution time cannot exceed 86400 seconds (24 hours)

2. HTTP Request

Execute HTTP-GET request.

Examples:

https://api.example.com/task/run
http://localhost:8080/webhook

Note

HTTP task execution time cannot exceed 300 seconds (5 minutes)

Task Configuration

Task Timeout

Tasks will be forcefully terminated after timeout. Default is 0 (no limit).

• Shell Tasks: Maximum execution time cannot exceed 86400 seconds
• HTTP Tasks: Maximum execution time cannot exceed 300 seconds

Task Retry on Failure

Tasks are marked as failed in the following situations:

• Unable to connect to remote host
• Shell command returns non-zero value
• HTTP response code is not 200

Retry Mechanism:

• Retry count can be set (range: 1-10)
• Retry interval = retry count × 1 minute
• Retries at intervals of 1 minute, 2 minutes, 3 minutes...

Example: Retry count set to 2

1. Task execution failed
2. Sleep 1 minute, first retry
3. If still failed, sleep 2 minutes, second retry
4. If still failed, task is finally marked as failed

Tip

Default value is 0, which means no retry

Single Instance Run

When single instance run is enabled, if the previous task has not been completed, the next task will not be executed, and the task log status will show "canceled".

This feature prevents duplicate task execution, especially suitable for long-running tasks.

Task Dependencies

gocron supports setting dependencies between tasks. When task A depends on task B:

• Task A will only start executing after task B executes successfully
• If task B fails, task A will not execute

Related Documentation

• Log Management
• API Documentation