Jenkins Cron Syntax Guide (2026) — Hash, H, and How to Stop the 3AM Stampede

2026-07-17 · By Avinash K

Jenkins cron looks like POSIX cron, but it has one feature no other scheduler has: the H (hash) symbol. Used correctly, it prevents the classic problem where every job on your controller fires at exactly 0 0 * * * and grinds the queue to a halt. This guide shows how to use it properly.

MIN HOUR DOM MON DOW
0-59 0-23 1-31 1-12 0-7  (0 and 7 both = Sunday)

Written inside a triggers { cron('...') } block in a declarative pipeline, or in the "Build periodically" box for freestyle jobs.

H tells Jenkins "pick a stable but hashed value based on the job name". Two jobs with H 2 * * * will each pick a different minute between 0 and 59 - deterministically, so they don't drift between restarts.

H * * * *         # once per hour, on a hashed minute
H/15 * * * *      # every 15 minutes, hashed start (0-14, 15-29, ...)
H 2 * * *         # daily at 2:HH, minute hashed by job name
H H(0-7) * * *    # daily some time between midnight and 7:59 AM
H H * * 1-5       # once a day on weekdays, fully spread

@hourly   ->  H * * * *
@daily    ->  H H * * *
@midnight ->  H H(0-2) * * *   (spreads across midnight +/- 2h)
@weekly   ->  H H * * H
@monthly  ->  H H H * *
@yearly   ->  H H H H *

Prefer these aliases in shared libraries - every downstream job gets automatic jitter without asking.

pipeline {
  agent any
  triggers {
    // Nightly regression, hashed to avoid the 2 AM stampede
    cron('H H(1-4) * * *')
    // Poll SCM every 5 min, hashed start
    pollSCM('H/5 * * * *')
  }
  stages {
    stage('Test') { steps { sh 'npm test' } }
  }
}

triggers {
  cron(env.BRANCH_NAME == 'main' ? 'H H(1-3) * * *' : '')
}

Only main gets a nightly build; feature branches skip the schedule.

A broken cron string silently disables the trigger - Jenkins won't fail the build config, it just never fires. Before committing, paste your expression into the Cron Expression Builder & Tester to see the next 10 run times, then use the Jenkins export tab to copy the exact triggers { cron('...') } block.