Cron job scheduling

Cron is a task scheduler that allows user to automate commands or scripts to run at specific times, dates, or intervals. This makes cron a powerful tool for system administrators and developers who want to automate repetitive tasks.

What can users automate with cron?

• System maintenance: Cron can be used to schedule regular backups, update software packages, or clean up temporary files.
• Data processing: Users can use cron to download data from the internet at specific times, process it, and generate reports.
• Sending notifications: Cron can be used to trigger emails or other notifications based on events or system logs.

Basically, any task that can be expressed as a command or script can be automated with cron.

Writing a cron job! On Linux like systems cron jobs can be added by adding a line to the crontab file, specifying the schedule and the command that needs to be run at that schedule. The cron schedule is expressed in the following format:

minute hour day_of_month month day_of_week

GoFr also allows an optional field for second as first part in the schedule format, like in the following format:

second minute hour day_of_month month day_of_week

Each field can take a specific value or combination of values to define the schedule. Users can use special characters like * (asterisk) to represent any value and , (comma) to separate multiple values. It also supports 0-n to define a range of values for which the cron should run and */n to define number of times the cron should run. Here n is an integer.

Adding cron jobs in GoFr applications

Adding cron jobs to GoFr applications is made easy with a simple injection of user's function to the cron table maintained by the GoFr. The minimum time difference between cron job's two consecutive runs is a minute as it is the least significant scheduling time parameter.

Cron job with generic format:

app.AddCronJob("* * * * *", "job-name", func(ctx *gofr.Context) {
	// the cron job that needs to be executed at every minute
})

Cron job with optional second in format:

app.AddCronJob("* * * * * *", "job-name", func(ctx *gofr.Context) {
    // the cron job that needs to be executed at every second
})

The AddCronJob methods takes three arguments—a cron schedule, the cron job name(for tracing) and the set of statements that are to be executed at the given schedule.

Example

package main

import (
	"time"

	"gofr.dev/pkg/gofr"
)

func main() {
	app := gofr.New()

	// Run the cron job every 5 hours(*/5)
	app.AddCronJob("* */5 * * *", "", func(ctx *gofr.Context) {
		ctx.Logger.Infof("current time is %v", time.Now())
	})

	// Run the cron job every 10 seconds(*/10)
	app.AddCronJob("*/10 * * * * *", "", func(ctx *gofr.Context) {
		ctx.Logger.Infof("current time is %v", time.Now())
	})

	app.Run()
}

Cron job metrics

GoFr automatically collects metrics for all registered cron jobs. These metrics are available on the /metrics endpoint (default port 2121) and include:

• app_cron_job_total: Total number of times a cron job has been triggered.
• app_cron_job_success: Number of successful executions.
• app_cron_job_failures: Number of failed executions (including panics).
• app_cron_job_duration: Duration of execution in seconds.

Each metric is labeled with the job (user-defined name) to allow fine-grained filtering and monitoring.

Check out the example on how to add cron jobs in GoFr: Visit GitHub