Chapter 3

APIs for Infrastructure Teams

DNS, cloud, webhooks, and automation patterns.

Learning objectives

  • Name infrastructure tasks automatable via API
  • Understand webhooks (server-to-server callbacks)
  • Sketch a safe automation flow for Workshop Co.

Panels are APIs with buttons

When Marcus clicks “Add A record” in a DNS panel, the browser sends an API request. Scripts skip the UI and call the same endpoint — useful for:

  • DNS updates during failover (Book 3 + 7)
  • Provisioning VPS instances
  • SSL certificate orders and renewals
  • Creating monitoring alerts
  • Posting to Rocket.Chat or Slack when a server is down

Webhooks — reverse APIs

A webhook is when a service POSTs to your URL when something happens:

Stripe → POST https://workshopco.ca/webhooks/stripe
Body: { "type": "checkout.session.completed", ... }

Your server verifies the signature, updates the database, sends confirmation email. Same pattern for contact forms posting to Rocket.Chat (Workshop Co. could mirror this).

Worked example — DNS failover script (conceptual)

# Pseudocode — not provider-specific
if health_check_fails("203.0.113.10"):
    dns_api.update_record(
        zone="workshopco.ca",
        name="www",
        type="A",
        value="198.51.100.5"  # Montreal DR
    )
    notify("Marcus", "Failover: DNS pointed to DR")
Idempotency

Good automation checks state before changing it. Running the failover script twice should not flip-flop records.

Design an automation

When Workshop Co. receives a contact form submission, Marcus wants:

  1. Message in team chat
  2. Row appended to a Google Sheet
  3. Optional: LLM summary of the visitor's question (preview of Book 8 capstone)

Draw the webhook/API flow: form → your server → which APIs?

Sample flow
  1. Browser POST → /contact-submit on Workshop Co. server
  2. Server POST → Rocket.Chat incoming webhook (chat)
  3. Server POST → Google Sheets API (append row)
  4. Server POST → LLM API with redacted PII (summary only if no email in prompt)

Check

Webhook vs polling — why is webhook preferred for “payment completed”?

Answer

Instant and efficient — Stripe pushes when ready. Polling would hammer the API every N seconds and delay confirmation.