VM Scheduler

What It Does

The VM scheduler manages the Pexip Infinity VMs by starting them during service hours and deallocating them outside service hours. This reduces Azure compute costs while keeping the Verify-by-Video service available during operating hours.

The active production scheduler is the Azure Function App func-pexip-vm-scheduler-prod. The older GitHub Actions VM scheduling workflows are deprecated and should remain disabled unless the Function App scheduler is intentionally rolled back.

Managed VMs

Environment	Management Node	Conference Node
Test	vm-node-mgmt-test	vm-node-conf-test
Production	vm-node-mgmt-core	vm-node-conf-core

Production scheduling targets:

• vm-node-mgmt-core in RG-NODE-MANAGEMENT
• vm-node-conf-core in RG-NODE-CONFERENCE

Schedule

The production scheduler uses the Azure Functions NCRONTAB expression:

0 5,25,35,55 * * * *

This runs at :05, :25, :35, and :55 every hour. Service hours are read from the IAS /video/v2/service_hours endpoint and evaluated with the scheduler’s pre/post service-hours buffer.

For example, if service hours are 07:00-17:00 America/Vancouver and the scheduler uses a 1-hour buffer, the target VM-on window is 06:00-18:00 Pacific. Because the timer runs at fixed minutes, the practical start and stop actions usually occur on the first scheduler run after the boundary, such as 06:05 and 18:05.

Pausing The Schedule

During maintenance windows, disable only the timer function so the Function App does not automatically start or deallocate VMs. This keeps the HTTP manual trigger available for one-off operations.

az functionapp config appsettings set \
  --resource-group rg-application \
  --name func-pexip-vm-scheduler-prod \
  --settings AzureWebJobs.timer_scheduler.Disabled=true

Confirm the app setting:

az functionapp config appsettings list \
  --resource-group rg-application \
  --name func-pexip-vm-scheduler-prod \
  --query "[?name=='AzureWebJobs.timer_scheduler.Disabled']"

If the Function App should be fully stopped, use the Azure Portal or az functionapp stop, but note that this also disables manual HTTP operations.

Resuming The Schedule

Re-enable the timer function after the maintenance window:

az functionapp config appsettings set \
  --resource-group rg-application \
  --name func-pexip-vm-scheduler-prod \
  --settings AzureWebJobs.timer_scheduler.Disabled=false

Confirm that timer_scheduler appears in the function list:

az functionapp function list \
  --resource-group rg-application \
  --name func-pexip-vm-scheduler-prod \
  --query "[].name" \
  -o table

Manual Operations

The Function App exposes a manual HTTP trigger for controlled one-off actions. Use this during maintenance if the VMs need to remain on outside service hours.

Supported actions:

Action	Effect
scale_up	Starts the configured VMs without running the longer post-start workflow
scale_down	Deallocates the configured VMs
post_start	Runs the downstream post-start workflow separately

Manual operations require the Function App key and should be run only by authorized operators.

Deprecated Workflow Files

The old workflow files still exist in the repository for history:

Workflow	Previous Environment	Status
vm-start-stop-test.yml	Test	Deprecated
vm-start-stop-prod.yml	Production	Deprecated

Do not re-enable these workflows unless the scheduler Function App has been intentionally disabled as part of a rollback.

Test Scheduler

If a test Function App such as pexip-vm-scheduler-test-func exists in Azure, confirm whether it is still required for test VM scheduling. It should either be documented as the active test scheduler or decommissioned if it was only used for validation.