How to swap deployment slots in Azure App Service?

Output: Change directory to the sample code. Deploy using the az webapp up command

It might take a few minutes to run. During command execution, it displays information like the following:

{
"app_url": "https://<AppName>.azurewebsites.net",
"location": "westeurope",
"name": "<app_name>",
"os": "Windows",
"resourcegroup": "<resource_group_name>",
"serverfarm": "appsvc_asp_Windows_westeurope",
"sku": "FREE",
"src_path": "/home/<username>/demoHTML/static-html-web-app",

After the deployment, one can access it from the browser using the URL below:

https://<AppName>.azurewebsites.net

3. Deploy updated code to the deployment slot

Let’s create a staging deployment slot and update or modify the code, and then deploy that updated code to a new staging slot.

3.1. Create staging deployment slot

In the cloud shell, run the az webapp deployment slot create command to create a deployment slot named staging.

az webapp deployment slot create -n $appName -g $resourceGroup --slot staging

A slot can be created using the Azure portal as well through the following steps:

Step 1: In the Azure portal, select Add Slot in the toolbar to open the Add a slot panel.

Image: Azure portal Add Slot

Step 2: In the Add a slot panel, enter the essential details and click on the Add button to save the changes.

3.2. Update code

Let’s update the content of the web app. In Cloud Shell, type code command to open a file in the editor.

code index.html

Output: index.html file will be opened in the editor. Here, change the content as you like and save it by using the command ctrl-s and exit by ctrl-q.

3.3 . Deploy to staging slot

For this next step, either a zip or a web application resource (WAR) file is required. In the cloud shell, run the zip command to create a zip file of the updated web app.

zip -r stagingcode.zip .

Output: It will create a zip folder with the name "stagingcode"

az webapp deploy -g $resourceGroup -n $appName --src-path ./stagingcode.zip --slot staging

Output: deploy updated zip into the staging slot

One can get the latest updated application changes from the staging URL below.

http://<AppName>-staging.azurewebsites.net

To verify the swap in the Azure portal, select Swap in the toolbar to open the Swap panel.

Image: Azure portal Slots

4. Swap from staging to production slots

Now, once validation completes, we can swap staging to production using the command az webapp deployment slot swap

az webapp deployment slot swap  -g $resourceGroup -n $appName --slot staging \ --target-slot production

Swap can be done from the Azure portal as well through the following steps:

Step 1: In the Azure portal, select Swap in the toolbar to open the Swap panel.

Image: Azure portal select Swap

Step 2: In the swap panel, review the settings such that Source should show the -staging slot and Target should show the default production slot.

Image: Azure portal Swap panel

Click on the Swap button at the bottom and wait for the operation to complete. One can verify the swap from the application URL or from the current production slot details.

Application URL will reflect the latest version of the application

http://<AppName>-staging.azurewebsites.net

5. Summary

Here, a deployment slot has been created and swapped using Azure Cloud Shell and Azure portal with git clone, az webapp up, az webapp deployment slot create, az webapp deployment slot swap, etc. commands..