[v1.2] WebhookHandler should respond to GET (for ALB / K8s health checks)

[MaxMansfield]

Context

The SDK's WebhookHandler (src/rtms/__init__.py:295 Python; equivalent in Node) only implements do_POST. Python's BaseHTTPRequestHandler defaults to 501 Not Implemented for unimplemented HTTP methods.

This breaks every cloud deployment behind a load balancer:

• AWS ALB target group health check matchers are hard-capped at 200-499 by AWS. Setting matcher = "200-599" returns: ValidationError: Health check matcher HTTP code '599' must be within '200-499' inclusive. So 501 is unmatchable, targets stay unhealthy, ALB returns 503 to all traffic including legitimate POST webhooks.
• Kubernetes liveness probes default to GET /healthz — same issue.
• GCP Load Balancer health checks have similar constraints.

Discovered during AWS Terraform deploy on 2026-05-20 — every cloud deployer hits this. Current workaround in the terraform-template worker/main.py is a WebhookHandler subclass that adds a do_GET returning 200, then rtms.WebhookHandler = subclass. Hack that every customer reinvents.

What to ship

Add do_GET to the SDK's WebhookHandler (both Python and Node). Pick one:

Option	Response	Pros / Cons
A. 200 OK + {"status":"ok"} body	Friendly for any health-probe tool, monitoring uptime checks, etc.	Implies a real endpoint at /.
B. 405 Method Not Allowed + Allow: POST header	More semantically correct — the webhook server is POST-only	Still in 200-499 range, ALB and K8s health checks both accept

Option B is the more honest HTTP. Either resolves the cloud-deploy gap. Recommendation: ship B.

Acceptance criteria

• Python WebhookHandler.do_GET implemented
• Node.js equivalent implemented (Node's stock http may not have this exact shape — match the spirit)
• Returns 405 with Allow: POST header (or 200 if you go with option A)
• examples/python.md and examples/node.md show the new behavior with an ALB / K8s health-check note
• Tested behind an actual ALB (matcher 200-299 or 200-499) — targets become healthy

Cross-language parity

• Python and Node ship same status code (both 405 or both 200)
• Same response body shape
• Both updated in the same release
• PR description includes "Cross-language parity check" section

Source

Tracked in vault: Projects/RTMS SDK v1.2.md → DEVS-X9.

Tracker

Part of the v1.2 milestone. Project: https://github.com/orgs/zoom/projects/11.