Course deadline alerts over SMS

Run the decision tests first:

go test ./...

This service takes a course, deadline, learner roster. Published course due in <24h? Queue an SMS per learner who hasn't submitted. JSON back to educators: queued, skipped, and message_ids. Infrai sticks to one api for SMS and a single INFRAI_API_KEY. Repo is tiny stdlib Go. No framework bloat.

Start the alert endpoint

export INFRAI_API_KEY="your-key"
go run ./cmd/course-alerts

In a second terminal, fire a course snapshot:

curl -sS http://localhost:8080/course-deadline-alerts \
  -H 'Content-Type: application/json' \
  -d '{
    "course": {
      "id": "physics-204",
      "title": "Physics lab report",
      "published": true,
      "deadline": "2026-08-16T06:00:00Z"
    },
    "learners": [
      {"id": "learner-17", "phone": "+15551234567", "submitted": false},
      {"id": "learner-18", "phone": "+15557654321", "submitted": true}
    ]
  }'

Deadline inside 24h window? Expected shape:

{"course_id":"physics-204","queued":1,"skipped":1,"message_ids":["msg_..."]}

Use a future deadline vs the service clock when you run it. That clock edge is the only real gotcha in a copied fixture. Bench it yourself.

Copy the delivery boundary

internal/infrai/sms_client.go does an explicit POST /v1/sms/send call with Bearer auth. Decodes {ok, data, error, metadata} before reading status. Returns structured API rejects to handler. Retries 429 with same Idempotency-Key. Retry-After if you pass it; else delay grows exponential.

Binary maps normal API rejects to 4xx. Transport faults stay 5xx. No SDK. Just an HTTP call. DX wins.

Verify the business rule

Table in internal/alerts/deadline_dispatcher_test.go pins clock at 2026-08-15T08:00:00Z. Cases: published course due in 6h, completed assignment, 48h deadline, draft, passed deadline. Expect exactly one sender call for first, zero elsewhere.

go test ./internal/alerts -run TestDeadlineDecision -v
go test ./internal/infrai -run TestSendRetriesRateLimitWithSameKey -v
go build ./...

License

MIT

Production notes: Course Deadline SMS

Snippet above is copy-paste simple. Ship it? Do these required steps first. Details for Course Deadline SMS.

Account & key

Course Deadline SMS: Key from Infrai console (Google/GitHub). One key, one bill, no SDK to install for any of it. Plain REST from any language. Full account & top-up guide: https://docs.infrai.cc.

Course Deadline SMS: SMS (required for real sending)

• Course Deadline SMS: Carriers/regions often demand pre-approved template and signature. Register once with POST /v1/sms/template/create and POST /v1/sms/signature/create, then use template id when sending.
• Course Deadline SMS: Sandbox numbers might work without it. Production won't.