Automating PoE Bounce for Offline APs with Mist API
ManagedNet runs Mist Wired Assurance for 180 customer sites, about 2,400 EX switches and 9,000 APs. The NOC receives a Mist webhook for every AP offline alarm. They want a Python service to auto-remediate: if an AP has been offline for more than 10 minutes and Mist shows the AP's switch port delivering PoE, the service should bounce PoE on that port once, wait 5 minutes, and open a ticket if the AP is still offline. Some APs are powered by midspan injectors, some switch ports are uplinks or trunk ports, and the service must not create a reboot loop. The Mist API token will be stored in a secrets manager. The team also wants a success metric and an audit trail for every automated action.
1. Design the workflow with guardrails. Which checks must happen before a PoE bounce, and how do you prevent repeat bounces?
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Receive the webhook into a queue, parse the alarm, and fetch current AP and switch-port state from Mist before acting. Confirm the AP has actually been offline for more than 10 minutes; do not trust a single alarm timestamp. Confirm the AP is connected to a switch port by LLDP or CDP, that the port is an access port for that AP and not an uplink, trunk, or another critical device, and that Mist reports PoE being delivered. Exclude APs powered by midspan injectors because bouncing the switch port will not help. Check for an active maintenance window. Use an idempotency key based on AP MAC and switch port, and keep a record of the last bounce. Allow at most one bounce per AP per 24 hours and one bounce at a time per switch. Call the Mist switch command to clear or bounce PoE, wait 5 minutes, then re-check AP status. If still offline, open a ticket with the evidence. Back off on API 429 responses and never run the workflow in a tight retry loop.
2. What API token scope and webhook design would you use, and why not an org-wide admin token?
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Use a dedicated service account with the least privilege needed to read device and port state and issue switch PoE commands, not a personal org-wide admin token. If the platform supports site-scoped roles, scope the token to the sites the service manages; otherwise use a role that can perform the required switch actions but cannot change org security settings, templates, or user accounts. Store the token in the secrets manager and rotate it on a schedule. The webhook should use HTTPS, validate a shared secret or signature, deduplicate by event ID, and tolerate retries. Subscribe only to the alarm topics needed. An org-wide admin token turns a webhook bug or leaked secret into a full-org compromise; a least-privilege token limits blast radius and makes audit easier.
3. How would you measure success and what would you log?
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Measure attempts, successful recoveries, false positives, repeat bounces, mean AP offline duration before and after automation, ticket volume, and API 429 rate. Compare automated sites with a control group of manually handled sites. Log the alarm ID, site, AP MAC, switch MAC, port, LLDP neighbor, PoE state, timestamp, action taken, API response, post-check result, and ticket ID. Write the audit record to an immutable log or SIEM and retain it per policy. Review false positives where the AP was on an injector or the port was an uplink; those indicate missing guardrails. A successful automation should reduce offline time without bouncing healthy APs or creating repeated reboot loops.