Azure App Service

1. What is Azure App Service?

• Supports multiple languages and frameworks: .NET, .NET Core, Java, Node.js, Python, PHP, Ruby, and containers.

• Provides built-in features such as auto-scaling, high availability, deployment slots, and continuous deployment.

• Offers 99.95% SLA for uptime.

2. Core Concepts of Azure App Service

3. App Service Plan and Pricing

Pricing Tiers Overview:

4. Development and Deployment

Supported Languages & Frameworks

• .NET, .NET Core, Java, Node.js, Python, PHP, Ruby

• Containers (Linux or Windows)

• Static sites and serverless functions (Azure Functions)

Developing Apps

• Visual Studio / Visual Studio Code

• Azure CLI

• Azure DevOps Pipelines (CI/CD)

• GitHub Actions

• FTP, WebDeploy, ZIP deploy

Sample: Deploying a Node.js Web App with Azure CLI

# Login to Azure
az login

# Create a resource group
az group create --name MyResourceGroup --location eastus

# Create App Service plan
az appservice plan create --name MyAppServicePlan --resource-group MyResourceGroup --sku B1 --is-linux

# Create a web app
az webapp create --resource-group MyResourceGroup --plan MyAppServicePlan --name MyUniqueAppName --runtime "NODE|14-lts"

# Deploy app from local folder (assumes you have zipped code in app.zip)
az webapp deployment source config-zip --resource-group MyResourceGroup --name MyUniqueAppName --src app.zip

5. Configuration & Application Settings

• Environment variables and connection strings can be set via Azure Portal or CLI.

• Configuration changes propagate without restarting the app.

• Supports deployment slot settings, which are sticky to slots (e.g., connection strings).

6. Scaling & High Availability

• Scale out (number of instances) or up (resource size: CPU, memory).

• Autoscaling triggers based on metrics like CPU, memory, HTTP queue length.

• Deployment slots allow zero-downtime deployments by swapping production and staging slots.

• Built-in load balancing and health monitoring.

7. Security & Identity Management

8. Monitoring & Diagnostics

• Application Insights integration for performance and usage telemetry.

• Log streaming to view real-time logs.

• Diagnostics logs: Web server logs, detailed error messages, failed request tracing.

• Alerts and metrics via Azure Monitor.

9. Advanced Features

• Deployment Slots: Create staging slots to test features pre-release. Swap slots to promote changes seamlessly.

• Backup and Restore: Automated and manual backup of app content and database.

• Hybrid Connections & VNet Integration: Connect to on-premises or other networks securely.

• Containers: Deploy custom Docker containers with full control over the runtime environment.

• WebJobs: Run background tasks or scheduled jobs within the App Service.

10. Sample Code Snippet for Authentication (Easy Auth with Azure AD)

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  if (!req.headers['x-ms-client-principal']) {
    res.status(401).send('Unauthorized');
    return;
  }
  const user = Buffer.from(req.headers['x-ms-client-principal'], 'base64').toString('ascii');
  res.send(`Hello, ${user}`);
});

app.listen(process.env.PORT || 3000);

11. Summary Table: Azure App Service Features

FAQ

1. Log in with az login.

2. Create a resource group (az group create).

3. Create an App Service Plan (az appservice plan create).

4. Create a web app (az webapp create) specifying runtime.

5. Deploy your app code via ZIP deploy or Git (az webapp deployment source config-zip).

Intermediate Questions and Answers

Advanced & Tricky Questions and Answers

Scenario-Based Questions (Brief Answers)

• For global high-availability, deploy multiple instances across regions, use Traffic Manager for routing, and replicate data globally (Cosmos DB).

• For blue/green testing, use deployment slots with staged validation and swap after approval.

• To integrate Key Vault, use Managed Identities and Key Vault references in app settings to avoid secret exposure.

• To diagnose memory leaks, use Application Insights Profiler and memory dumps.

• To restrict traffic by IP, configure access restrictions in Networking blade or use Azure Front Door/WAF.

App Service and DevOps Questions

• CI/CD pipeline with rollback: Use Azure DevOps pipelines with stages for build, test, deploy to staging slot; swap on success; retain previous version for rollback.

• Database migrations during deployment: Add migration scripts in deployment steps or execute migrations in startup code conditioned on environment.