Go Language

How to Schedule Cron Jobs in Golang

This golang tutorial help to create schedule a jon to execute at specific time interval

Golang Community Moderator. Software Engineer - Open Source Enthusiast. Goper Lover

Published · Oct 21 2019

  
 This golang tutorial help to create schedule a jon to execute at specific time interval.This is very helpful feature to run a process or tasks as background, that can be a job that pull data from third party server, sync data between two server, send an email notification at a specific inerval.  

Getting started
To get the package, execute:
go get gopkg.in/robfig/cron.v2

 To import this package, add the following line to your code:
import "gopkg.in/robfig/cron.v2"

Usage
Callers may register Funcs to be invoked on a given schedule.  Cron will run them in their own goroutines. 

CRON Expression Format
A cron expression represents a set of times, using 6 space-separated fields. 
Field name     Mandatory?   Allowed values    Allowed special characters
----------     ----------   --------------    --------------------------
Seconds        No           0-59              * / , -
Minutes        Yes          0-59              * / , -
Hours          Yes          0-23              * / , -
Day of month   Yes          1-31              * / , - L W
Month          Yes          1-12 or JAN-DEC   * / , -
Day of week    Yes          0-6 or SUN-SAT    * / , - L #
Year           No           1970–2099         * / , -

 Note: Month and Day-of-week field values are case insensitive.  "SUN", "Sun", and "sun" are equally accepted. 

Predefined schedules
You may use one of several pre-defined schedules in place of a cron expression. 
Entry       Description                                                             Equivalent to
@annually   Run once a year at midnight in the morning of January 1                 0 0 0 1 1 * *
@yearly     Run once a year at midnight in the morning of January 1                 0 0 0 1 1 * *
@monthly    Run once a month at midnight in the morning of the first of the month   0 0 0 1 * * *
@weekly     Run once a week at midnight in the morning of Sunday                    0 0 0 * * 0 *
@daily      Run once a day at midnight                                              0 0 0 * * * *
@hourly     Run once an hour at the beginning of the hour                           0 0 * * * * *

Intervals
You may also schedule a job to execute at fixed intervals.  This is supported by formatting the cron spec like this: 
@every <duration>

 where "duration" is a string accepted by time.ParseDuration (http://golang.org/pkg/time/#ParseDuration). 

For example, "@every 1h30m10s" would indicate a schedule that activates every 1 hour, 30 minutes, 10 seconds. 

Note: The interval does not take the job runtime into account.  For example, if a job takes 3 minutes to run, and it is scheduled to run every 5 minutes, it will have only 2 minutes of idle time between each run. 