Local Development Guide¶

1. Development Environment¶

Recommended: - Python 3.11+ - Azure Functions Core Tools 4.x - Docker (for DB integration tests) - Azurite or an actual dev storage account as an alternative to Azure Storage Emulator - uv or pip + venv

2. Creating an Azure Functions Python v2 App¶

func init myfuncapp --python
cd myfuncapp
func new --name orders_poll --template "Timer trigger"

Afterwards, organize the project around function_app.py following the Python v2 structure.

3. Installing Dependencies¶

python -m venv .venv
source .venv/bin/activate
pip install -r examples/requirements.txt

4. Checking host.json¶

Keep the extension bundle 4.x range in host.json.

{
  "version": "2.0",
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.0.0, 5.0.0)"
  }
}

5. local.settings.json¶

Example:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "python",
    "ORDERS_DB_URL": "postgresql+psycopg://postgres:postgres@localhost:5432/orders"
  }
}

6. Running Locally¶

func start

7. Recommended Local Test Sequence¶

Pure unit tests
SQLite smoke test
Docker Postgres integration test
Docker MySQL integration test
Docker SQL Server integration test
Local Functions runtime smoke test

8. Sample DB for Development¶

PostgreSQL¶

table: orders
cursor: updated_at
pk: id

Seed Example¶

CREATE TABLE orders (
  id BIGSERIAL PRIMARY KEY,
  status TEXT NOT NULL,
  total_amount NUMERIC(12,2) NOT NULL,
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

INSERT INTO orders (status, total_amount) VALUES
('created', 10.50),
('paid', 20.00);

9. Local Debugging Checkpoints¶

checkpoint JSON contents
generated SQL
fetched batch size
lease owner / fencing token
handler execution time
commit success status

10. Caveats¶

updated_at must be reliably updated by the application.
Do not mix local clock and DB timezone.
An empty batch is a success case.
Hard deletes are not captured by default polling.