Sea Haven Door Unlock API

AWS Lambda middleware that allows Yealink desk phones to unlock the front door and manage lockdown profiles via LenelS2 Elements.

Yealink T54W/T58W → HTTPS GET (?token=) → API Gateway (token authorizer) → Lambda → LenelS2 Elements API

Architecture

• API Gateway (HTTP API) — GET /unlock, GET /lockdown, GET /lockdown/status with throttling (5 burst / 2 sustained req/sec)
• Token authorizer Lambda — a REQUEST-type Lambda authorizer validates the ?token= query-string value (the same shared secret the phones already send) against the /seahaven/door-unlock/auth-token SSM parameter, so unauthenticated callers are rejected at the gateway (401/403) before any handler runs. Identity source is $request.querystring.token; results are cached 5 minutes. Fail-closed. The handlers also re-validate the token as defense-in-depth.
• Unlock Lambda — validates a shared auth token, calls the Elements TemporaryUnlock command
• Lockdown Lambda — toggles lockdown profiles (start/stop) and checks status, returns Yealink XML TextScreen responses
• Lockdown Poller Lambda — VPC-connected, polls Elements API every 15 seconds for lockdown status (runs 4x per 1-minute EventBridge schedule)
• SSM Parameter Store — stores the Elements API key, auth token, door ID, and phone IPs
• Secrets Manager — stores the Yealink phone admin password
• Custom Domain — doorunlock.seahaven.com via Route 53 + ACM wildcard cert
• CloudWatch alarms — one error alarm per Lambda (unlock, lockdown, authorizer, poller); each fires on Errors > 0 and notifies the cross-stack site-alerts SNS topic (ALARM state only)

Infrastructure (CDK)

All infrastructure is defined as code with the AWS CDK v2 (TypeScript); aws-cdk-lib is pinned to 2.261.0. The whole system is a single CloudFormation stack.

Layout

bin/app.ts                    # CDK app entry point
lib/door-unlock-stack.ts      # DoorUnlockStack — all resource definitions
lambda/
├── unlock/unlock-handler.ts        # Unlock Lambda
├── lockdown/lockdown-handler.ts    # Lockdown Lambda
├── poller/lockdown-poller.ts       # Lockdown Poller Lambda
└── authorizer/authorizer-handler.ts # Token authorizer Lambda
cdk.json                      # CDK config (app command, watch, context flags)

bin/app.ts

Instantiates DoorUnlockStack with an explicit stackName of seahaven-door-unlock-api, pinned to account 328440206208 / us-east-1.

lib/door-unlock-stack.ts

Defines every resource the stack owns:

• The four Lambda functions (Node 24.x, arm64, 60-day log retention), bundled from TypeScript with esbuild
• The HTTP API (door-unlock-api), its GET /unlock, GET /lockdown, and GET /lockdown/status routes, throttling, and JSON access logging
• The HttpLambdaAuthorizer token authorizer (identity source $request.querystring.token, 5-minute result cache)
• The EventBridge rule that invokes the poller once a minute, plus the poller's VPC config and security group (imported VPC/subnets, egress to the Elements API and phone LAN)
• The custom domain, ACM certificate import, and Route 53 A record for doorunlock.seahaven.com
• Imports of the SSM parameters, the phone-password secret, and the site-alerts SNS topic, with the corresponding grantRead IAM permissions
• The four per-Lambda CloudWatch error alarms

cdk.json

CDK configuration committed to the repo. The app command runs npx tsx bin/app.ts, so the TypeScript entry point executes directly via tsx (no separate compile step). It also carries the watch include/exclude globs and the CDK feature-flag context.

Commands

npx cdk synth   # synthesize the CloudFormation template
npx cdk diff    # diff against the deployed stack
npx cdk deploy  # deploy (see Manual Deployment below)

The same commands are also exposed as npm scripts (npm run synth, npm run diff, npm run deploy).

Documentation

The canonical map of Sea Haven's AWS infrastructure lives in Confluence. This project's seahaven-door-unlock-api stack is represented there as a Mermaid subgraph.

• AWS Architecture Map (Confluence, IT space, page 1540098)

Lockdown Profiles

Two lockdown profiles are configured:

Profile	Elements ID	Line Key
Bohemia - Whole Building	4b4a3e6b-c903-4cce-8cd6-288612bf0542	3
Ronkonkoma - Whole Building	ff9876bc-c54f-472e-aef9-d2bffd4b7cf7	4

Pressing the line key toggles the lockdown on/off and displays the current status on the phone screen.

Known limitation: Line key LED color does not currently change to reflect lockdown status. The T58W's XML Browser key type (17) does not support persistent LED color changes via Push XML or Execute commands — LED commands are transient and immediately overridden by the phone's key type management.

SSM Parameters

Parameter	Type	Description
/seahaven/door-unlock/elements-api-key	SecureString	LenelS2 Elements API key
/seahaven/door-unlock/auth-token	SecureString	Shared secret embedded in the Yealink DSS key URL
/seahaven/door-unlock/door-id	String	Elements device ID for the front door reader
/seahaven/door-unlock/phone-ips	String	Comma-separated phone IPs for lockdown poller

Secrets Manager

Secret	Description
door-unlock-api/phone-password	Yealink phone admin password for Push XML

CI/CD

GitHub Actions, using the Sea Haven reusable workflows:

• .github/workflows/ci.yaml — on pull requests to main, runs the ci-typescript-cdk reusable workflow (build, lint, synth).
• .github/workflows/deploy.yaml — on push to main, runs the cd-cdk reusable workflow which assumes the githubdeploy-seahaven-door-unlock-api OIDC role (AWS_DEPLOY_ROLE_ARN repo secret) and runs cdk deploy.

The legacy CodePipeline/CodeBuild deploy path has been fully decommissioned.

Manual Deployment

npm install
npx cdk deploy

Phone Configuration

Configure DSS keys on the Yealink T54W/T58W (via phone web UI or 3CX):

• Key 2 — Unlock Door

  • Type: URL
  • Value: https://doorunlock.seahaven.com/unlock?token=<auth-token>

• Keys 3-4 — Lockdown Toggle

  • Type: XML Browser (17)
  • Value: https://doorunlock.seahaven.com/lockdown?token=<auth-token>&profile=bohemia|ronkonkoma

3CX Provisioning Templates

Custom 3CX templates are included with door unlock and lockdown URLs hardcoded.

Template	Model	Key 2	Keys 3-4	Display
yealinkT54W-door-unlock.ph.xml	T54W	Unlock Door	Managed by 3CX BLF	Dim after 5 min, never sleep
yealinkT54W-door-unlock-with-sp.ph.xml	T54W	Unlock Door	Shared Parking SP1-3	Dim after 5 min, never sleep
yealinkT58W-door-unlock.ph.xml	T58W	Unlock Door	Lockdown Toggle (Bohemia/Ronkonkoma)	Default T58W display settings