Hand-on demonstration – Create and Verify a Web-app and add Deployment Slots in Azure App Service

Creating and managing a web app in Azure App Service along with adding deployment slots is a powerful way to handle multiple environments like development, staging, and production.

Deployment slots allow you to deploy your web app to different environments without affecting the production app directly.

This setup also facilitates blue-green deployments and canary releases for smoother rollouts.

Here's how to create a web app, verify it, and add deployment slots in Azure.

Step 1: Create a Web App in Azure

1. Log in to Azure Portal:

2. Create an App Service:

   • In the Azure portal, in the left sidebar, click on "Create a resource".

   • In the Search box, type App Service and select App Service.

   • Click Create to begin the setup process.

3. Configure the Web App:

   • Subscription: Select the Azure subscription that you want to use.

   • Resource Group: Either choose an existing resource group or create a new one.

   • Name: Enter a unique name for your app (this will be the DNS name of your app, e.g., yourappname.azurewebsites.net).

   • Publish: Choose Code if you're deploying an app with code, or Docker if you're using containers.

   • Runtime stack: Select the runtime stack that matches your app (e.g., .NET, Node.js, Python, Java).

   • Region: Select the Azure region where your app will be hosted.

     • It’s generally a good idea to select a region close to your primary user base for better performance.

   • App Service Plan: Choose or create an App Service Plan.

     • The App Service Plan defines the pricing tier (e.g., Free, Basic, Standard) and the resources available for your app.

     • Choose the Standard plan if you need deployment slots.

   • Monitoring: Optionally, enable Application Insights for monitoring your app.

4. Review and Create:

   • Review your settings and click Create to deploy the web app.

   • Azure will now deploy your app and you can monitor the progress in the Notifications section.

Step 2: Verify Your Web App

Once the app is created, verify that it's working by accessing it through the default Azure URL (yourappname.azurewebsites.net).

1. Access the Web App:

   • In the Azure Portal, navigate to App Services and select your newly created app.

   • Under the Overview tab, find the default URL for your app (e.g., yourappname.azurewebsites.net).

   • Click on the URL or copy it to your browser to verify that your web app is live.

2. Check App Settings:

   • Under the Configuration section, ensure that any necessary environment variables or connection strings are set correctly.

3. Deploy Code:

   • Deploy your code via GitHub, Azure DevOps, FTP, or local Git.

     • You can also manually upload files using the Kudu console.

   • For continuous deployment, configure deployment sources in the Deployment Center.

Step 3: Add Deployment Slots

Deployment Slots allow you to deploy your app to a non-production environment and swap it with the production environment with zero downtime.

1. Navigate to Deployment Slots:

   • In the Azure Portal, go to App Services and select your web app.

   • Under the Deployment section in the left menu, click "Deployment slots".

2. Add a Deployment Slot:

   • Click "Add Slot".

   • Slot Name: Provide a name for your new slot, e.g., staging, dev, or test.

   • Clone settings from production: If you want the new slot to inherit all settings from the production slot (including app settings, connection strings, etc.), select "Clone settings from production".

   • If you don't want to clone settings, uncheck this option and configure the slot settings manually later.

   • Click "Add" to create the slot.

3. Configure the Deployment Slot:

   • Once the slot is created, it will be listed under Deployment slots. You can now:

     • Deploy code to the slot using your chosen deployment method (Azure DevOps, GitHub, FTP, etc.).

     • Configure slot-specific settings, such as environment variables or app settings that might differ from production.

4. Set up a Custom Domain for the Slot (Optional):

   • You can assign a custom domain to your deployment slot, similar to how you assign one to the production web app.

   • In Deployment slots, select the slot you want, and under Custom domains, add the custom domain you want to map to that slot (e.g., staging.yourdomain.com).

Step 4: Swap Deployment Slots

Once you've deployed and verified the code in a slot (e.g., staging), you can swap it with the production slot to push the changes to live.

1. Navigate to Deployment Slots:

   • In your web app’s settings, go to Deployment slots.

2. Swap Slots:

   • Click on Swap at the top of the page.

   • Source Slot: Choose the slot you want to swap (e.g., staging).

   • Target Slot: Choose the production slot (or another target slot).

   • Optionally, check "Preserve slot settings" if you want to keep the configuration settings from the target slot (e.g., production settings).

3. Confirm the Swap:

   • Click Swap to perform the swap operation.

   • After the swap is complete, your staging slot’s code will become the live code, and the production code will be moved to the staging slot.

4. Warm-up Slot:

   • When swapping slots, you can also warm-up the new slot to reduce cold start times.

   • This is especially useful for production slots to minimize downtime during the swap.

Step 5: Monitor and Manage Deployment Slots

1. Monitor Slot Performance:

   • You can monitor the performance and health of each deployment slot via Azure Monitor and Application Insights.

   • Set up alerts for any failures or issues in the slots, especially for your staging and production slots.

2. Slot-Specific Settings:

   • App Settings and Connection Strings: Each slot can have its own environment settings, connection strings, and app configurations.

     • These settings are not shared between slots unless you choose to clone them during the slot creation.

   • Scaling: You can scale each deployment slot separately if you need to adjust resource allocation based on the needs of that environment.

Things to Consider When Using Deployment Slots

1. Cost: Deployment slots are available only on Standard, Premium, or Isolated App Service plans. Slots are considered separate apps and will use additional resources, so keep this in mind for cost management.

2. Slot Settings: Be aware that slot-specific settings (like connection strings or app settings) can be different between slots. Ensure that sensitive settings (e.g., production database keys) are only present in the production slot.

3. Custom Domains: Deployment slots can use custom domains, but remember that you may need to configure DNS settings for each slot if using them for environments like staging.

4. Swap Conflicts: When swapping slots, make sure to handle any configuration changes (like database connection strings) that might cause conflicts when swapping environments.

Summary

Creating a web app in Azure, verifying it, and adding deployment slots is a straightforward process that greatly enhances the deployment and testing workflow for your app.

By using deployment slots, you can safely test new features in a staging environment and swap them with production with minimal downtime, making your deployment process more robust and risk-free.