Skip to main content

Job scheduler with approval steps

To schedule a job that pauses for a human approval, write it as a Windmill flow, add an approval step between the step that prepares the change and the step that applies it, and attach a cron schedule to the flow. On each run, the flow does the preparation, sends an approval link, and waits. It continues when someone approves, and stops if someone rejects or the timeout passes. Approval steps and schedules are both in the open-source Community Edition.

The example below disables inactive user accounts every Monday at 9:00, after a person has approved the list.

1. The flow​

The flow has three steps:

  1. a finds the inactive accounts.
  2. b sends the approval link, and the flow suspends after it.
  3. c disables the accounts, using the list from step a.

This is the flow's OpenFlow definition, as the CLI stores it in f/ops/disable_inactive_accounts.flow/flow.yaml. You can build the same flow in the flow editor.

summary: Disable inactive accounts, after approval
schema:
  type: object
  properties:
    inactive_days:
      type: integer
      default: 90
  required: []
value:
  modules:
    - id: a
      summary: Find inactive accounts
      value:
        type: rawscript
        language: python3
        content: |
          def main(inactive_days: int):
              # Query your user directory here.
              return [
                  {"email": "[email protected]", "last_login_days": inactive_days + 12},
                  {"email": "[email protected]", "last_login_days": inactive_days + 40},
              ]
        input_transforms:
          inactive_days:
            type: javascript
            expr: flow_input.inactive_days
    - id: b
      summary: Ask for approval
      value:
        type: rawscript
        language: python3
        content: |
          import wmill


          def main(accounts: list):
              urls = wmill.get_resume_urls()
              # Send this link to the approver by Slack, Teams or email.
              print("Approve or reject:", urls["approvalPage"])
              return {"accounts_to_disable": len(accounts)}
        input_transforms:
          accounts:
            type: javascript
            expr: results.a
      suspend:
        required_events: 1
        timeout: 86400
    - id: c
      summary: Disable the accounts
      value:
        type: rawscript
        language: python3
        content: |
          def main(accounts: list):
              # Call your identity provider's API here.
              return {"disabled": [a["email"] for a in accounts]}
        input_transforms:
          accounts:
            type: javascript
            expr: results.a

The suspend block on step b is what makes it an approval step:

  • required_events: 1: one approval resumes the flow. Raise it to require several approvers.
  • timeout: 86400: if nobody answers within 24 hours, the flow is canceled. To handle a rejection or a timeout in a later step instead of failing, enable continue on disapproval/timeout.

wmill.get_resume_urls() returns the approvalPage, resume and cancel URLs for this run. The example prints the approval page link; in practice, send it where the approver will see it. The Windmill clients include helpers that post an interactive approval to Slack or Microsoft Teams.

When the flow runs, steps a and b complete and the flow waits before step c. Opening the approval page shows the request with Approve and Deny buttons. After an approval, step c runs and the flow returns:

{"disabled": ["[email protected]", "[email protected]"]}

Deploy the flow from the CLI with:

wmill generate-metadata f/ops/disable_inactive_accounts.flow --yes
wmill flow push f/ops/disable_inactive_accounts.flow f/ops/disable_inactive_accounts

2. The schedule​

Add a schedule from the flow's Triggers tab, or from the Schedules page. Windmill cron expressions have six fields, starting with seconds, so Monday at 9:00 is:

0 0 9 * * 1

Pick the timezone in the schedule settings: with Europe/Paris, the next run of this schedule was computed as Monday 08:00 UTC, which is 9:00 in Paris. The schedule also stores the flow's arguments, here inactive_days: 90. See cron syntax for the supported expressions.

Each scheduled run appears in the runs page with its steps and logs.

Who can approve​

By default, anyone who has the approval link can approve or reject, so treat the link as a secret and send it only to the approvers. These controls are Cloud and Enterprise Edition features:

On Enterprise Edition, the reason given for a rejection is recorded in the audit log.

Edition notes​

The flow, the approval step with its links and timeout, the schedule and its timezone run on the Community Edition, as shown above. Approver permissions, approval forms, and a schedule error handler that alerts you when a scheduled run fails are Cloud and Enterprise Edition features.

Suspend and approval steps
All the options of approval steps, including forms, Slack and Teams.
Schedules
Cron syntax, timezones, error and recovery handlers.