Azure Functions
Build and deploy serverless applications with Azure Functions. Covers function app creation, trigger and binding configuration, deployment strategies, real code examples in Python and Node.js, and production best practices.
When to Use
- You need event-driven compute that scales automatically to zero.
- You are building APIs, webhooks, or background processing pipelines.
- You want per-execution billing without managing servers.
- You need to respond to Azure service events (Blob Storage, Service Bus, Cosmos DB changes).
- You are implementing lightweight microservices or scheduled tasks.
Historical snippets require current runtime/plan/region and extension compatibility verification; scale-to-zero, billing and slot support vary by plan. Confirm subscription/resource IDs, cost, secrets, storage and rollback before provisioning/deploying/swapping. Function keys are shared access secrets, not user/object-level authorization. HTTP records here are synthetic examples, not persisted users. Validate/allowlist request fields and never spread arbitrary input into protected output/state.
Prerequisites
bash
# Install Azure CLI
# Prerequisite: organization-approved Azure CLI installed from a verified signed package.
az version
# Install Azure Functions Core Tools v4
npm install -g azure-functions-core-tools@4
# Verify installation
func --version
# Login
az login
az account set --subscription "my-subscription-id"
# Create supporting resources
az group create --name functions-rg --location eastus
az storage account create \
--name myfuncstorageacct \
--resource-group functions-rg \
--location eastus \
--sku Standard_LRS
Function App Creation
Consumption Plan (Pay-per-execution)
bash
# Python function app on Consumption plan
az functionapp create \
--resource-group functions-rg \
--consumption-plan-location eastus \
--runtime python \
--runtime-version 3.11 \
--functions-version 4 \
--name myapp-func \
--storage-account myfuncstorageacct \
--os-type Linux
# Node.js function app
az functionapp create \
--resource-group functions-rg \
--consumption-plan-location eastus \
--runtime node \
--runtime-version 20 \
--functions-version 4 \
--name myapp-node-func \
--storage-account myfuncstorageacct \
--os-type Linux
Premium Plan (VNet integration, no cold start)
bash
# Create Premium plan
az functionapp plan create \
--resource-group functions-rg \
--name myapp-premium-plan \
--location eastus \
--sku EP1 \
--is-linux true
# Create function app on Premium plan
az functionapp create \
--resource-group functions-rg \
--plan myapp-premium-plan \
--runtime python \
--runtime-version 3.11 \
--functions-version 4 \
--name myapp-premium-func \
--storage-account myfuncstorageacct
Trigger and Binding Examples
HTTP Trigger -- Python
python
# function_app.py (v2 programming model)
import azure.functions as func
import json
import logging
app = func.FunctionApp(http_auth_level=func.AuthLevel.FUNCTION)
@app.route(route="users/{userId}", methods=["GET"])
def get_user(req: func.HttpRequest) -> func.HttpResponse:
user_id = req.route_params.get("userId")
logging.info(f"Fetching user: {user_id}")
if not user_id:
return func.HttpResponse(
json.dumps({"error": "userId is required"}),
status_code=400,
mimetype="application/json"
)
user = {"id": user_id, "name": "Jane Doe", "email": "jane@example.com"}
return func.HttpResponse(
json.dumps(user),
status_code=200,
mimetype="application/json"
)
@app.route(route="users", methods=["POST"])
def create_user(req: func.HttpRequest) -> func.HttpResponse:
try:
body = req.get_json()
except ValueError:
return func.HttpResponse(
json.dumps({"error": "Invalid JSON"}),
status_code=400,
mimetype="application/json"
)
logging.info(f"Creating user: {body.get('name')}")
return func.HttpResponse(
json.dumps({"id": "new-id", "name": body.get("name")}),
status_code=201,
mimetype="application/json"
)
HTTP Trigger -- Node.js
javascript
// src/functions/httpTrigger.js (v4 programming model)
const { app } = require("@azure/functions");
app.http("getUser", {
methods: ["GET"],
authLevel: "function",
route: "users/{userId}",
handler: async (request, context) => {
const userId = request.params.userId;
context.log(`Fetching user: ${userId}`);
if (!userId) {
return { status: 400, jsonBody: { error: "userId is required" } };
}
const user = { id: userId, name: "Jane Doe", email: "jane@example.com" };
return { status: 200, jsonBody: user };
},
});
app.http("createUser", {
methods: ["POST"],
authLevel: "function",
route: "users",
handler: async (request, context) => {
const body = await request.json();
context.log(`Creating user: ${body.name}`);
return { status: 201, jsonBody: { id: "new-id", name: body.name } };
},
});
Blob Trigger -- Python
python
@app.blob_trigger(arg_name="blob", path="uploads/{name}",
connection="AzureWebJobsStorage")
def process_upload(blob: func.InputStream):
logging.info(f"Processing blob: {blob.name}, Size: {blob.length} bytes")
content = blob.read()
# Process file content here
Timer Trigger -- Python
python
@app.timer_trigger(schedule="0 */5 * * * *", arg_name="timer",
run_on_startup=False)
def cleanup_job(timer: func.TimerRequest):
if timer.past_due:
logging.warning("Timer is past due")
logging.info("Running scheduled cleanup")
# Cleanup logic here
Service Bus Trigger -- Python
python
@app.service_bus_queue_trigger(arg_name="msg", queue_name="orders",
connection="ServiceBusConnection")
@app.cosmos_db_output(arg_name="doc", database_name="mydb",
container_name="processed-orders",
connection="CosmosDBConnection")
def process_order(msg: func.ServiceBusMessage, doc: func.Out[func.Document]):
order = json.loads(msg.get_body().decode("utf-8"))
logging.info(f"Processing order: {order['id']}")
processed = {
"id": order["id"],
"status": "processed",
"items": order["items"],
"total": sum(item["price"] for item in order["items"])
}
doc.set(func.Document.from_dict(processed))
Cosmos DB Change Feed Trigger -- Python
python
@app.cosmos_db_trigger_v3(arg_name="documents", database_name="mydb",
container_name="orders",
connection="CosmosDBConnection",
lease_container_name="leases",
create_lease_container_if_not_exists=True)
def on_order_change(documents: func.DocumentList):
for doc in documents:
logging.info(f"Document changed: {doc['id']}")
Local Development
bash
# Initialize a new Python function project
func init MyFunctionProject --python
cd MyFunctionProject
# Create a new function from template
func new --name HttpExample --template "HTTP trigger" --authlevel function
# Run locally
func start
# Run locally with specific port
func start --port 7072
# Test locally
curl http://localhost:7071/api/HttpExample?name=World
Deployment
bash
# Deploy using Core Tools
func azure functionapp publish myapp-func
# Deploy with build step for Python
func azure functionapp publish myapp-func --build remote
# Deploy using ZIP package
zip -r function.zip . -x ".git/*" ".venv/*" "__pycache__/*" "local.settings.json" ".env" ".env.*"
# Inspect the complete archive allowlist before upload; exclusion patterns alone
# cannot establish that keys, private files or old archives are absent.
az functionapp deployment source config-zip \
--resource-group functions-rg \
--name myapp-func \
--src function.zip
# Deploy via CI/CD with GitHub Actions
az functionapp deployment github-actions add \
--resource-group functions-rg \
--name myapp-func \
--repo "myorg/myrepo" \
--branch main \
--runtime python \
--login-with-github
Deployment Slots
bash
# Create a staging slot
az functionapp deployment slot create \
--resource-group functions-rg \
--name myapp-func \
--slot staging
# Deploy to staging slot
func azure functionapp publish myapp-func --slot staging
# Test staging slot
curl https://myapp-func-staging.azurewebsites.net/api/health
# Swap staging to production
az functionapp deployment slot swap \
--resource-group functions-rg \
--name myapp-func \
--slot staging \
--target-slot production
# Roll back by swapping again
az functionapp deployment slot swap \
--resource-group functions-rg \
--name myapp-func \
--slot staging \
--target-slot production
Application Settings and Security
bash
# Set application settings
az functionapp config appsettings set \
--resource-group functions-rg \
--name myapp-func \
--settings \
ServiceBusConnection="Endpoint=sb://..." \
CosmosDBConnection="AccountEndpoint=https://..." \
CUSTOM_SETTING="my-value"
# Set settings as slot-specific
az functionapp config appsettings set \
--resource-group functions-rg \
--name myapp-func \
--slot-settings \
ENVIRONMENT="staging"
# Enable managed identity
az functionapp identity assign \
--resource-group functions-rg \
--name myapp-func
# Configure CORS
az functionapp cors add \
--resource-group functions-rg \
--name myapp-func \
--allowed-origins "https://myapp.example.com"
# Set minimum TLS version
az functionapp config set \
--resource-group functions-rg \
--name myapp-func \
--min-tls-version 1.2
# Enable Application Insights
az functionapp config appsettings set \
--resource-group functions-rg \
--name myapp-func \
--settings APPINSIGHTS_INSTRUMENTATIONKEY="your-key"
Terraform Configuration
hcl
resource "azurerm_service_plan" "functions" {
name = "myapp-func-plan"
location = azurerm_resource_group.main.location
resource_group_name = azurerm_resource_group.main.name
os_type = "Linux"
sku_name = "Y1" # Consumption plan
}
resource "azurerm_linux_function_app" "main" {
name = "myapp-func"
location = azurerm_resource_group.main.location
resource_group_name = azurerm_resource_group.main.name
service_plan_id = azurerm_service_plan.functions.id
storage_account_name = azurerm_storage_account.func.name
storage_account_access_key = azurerm_storage_account.func.primary_access_key
identity {
type = "SystemAssigned"
}
site_config {
application_stack {
python_version = "3.11"
}
cors {
allowed_origins = ["https://myapp.example.com"]
}
}
app_settings = {
FUNCTIONS_WORKER_RUNTIME = "python"
WEBSITE_RUN_FROM_PACKAGE = "1"
APPINSIGHTS_INSTRUMENTATIONKEY = azurerm_application_insights.main.instrumentation_key
}
tags = var.tags
}
Troubleshooting