Deployment slots for staging in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a deployment slot in Azure App Service?

A deployment slot is a live app environment with its own hostname. It allows you to deploy and test your app in a staging environment before swapping it with the production slot.

beginner

Why use deployment slots for staging?

Deployment slots let you test new app versions in a real environment without affecting users. You can swap slots to release updates with zero downtime.

intermediate

What happens during a slot swap in Azure App Service?

During a swap, the content and configuration of the staging slot exchange with the production slot. This makes the staging version live and the old production version moves to staging.

intermediate

Can deployment slots have different configurations?

Yes, deployment slots can have slot-specific settings like connection strings or app settings that do not swap with the content. This helps keep staging and production environments separate.

intermediate

What is a best practice when using deployment slots for staging?

Test your app thoroughly in the staging slot before swapping. Also, use slot-specific settings for sensitive data and monitor the app after swap to catch issues early.

What is the main benefit of using deployment slots for staging in Azure?

A Zero downtime deployment

B Lower hosting costs

C Faster app development

D Automatic scaling

Deployment slots allow you to swap staging and production environments without downtime, ensuring users experience no interruption.

Which of the following is true about slot-specific settings?

A They swap along with the app content

B They are deleted after swap

C They cannot be configured separately

D They remain unique to each slot during swap

Slot-specific settings stay with their slot and do not swap, allowing different configurations for staging and production.

What happens to the production slot when you swap it with a staging slot?

A It is deleted

B It becomes the new staging slot

C It remains unchanged

D It restarts automatically

The production slot and staging slot exchange their content and configurations, so production becomes staging and vice versa.

Which scenario best describes when to use deployment slots?

A To test app updates before releasing to users

B To reduce app hosting costs

C To store backups of the app

D To increase app storage space

Deployment slots provide a staging environment to test updates safely before making them live.

Can deployment slots be used for production traffic?

A Only during swap operations

B No, only production slot can serve traffic

C Yes, each slot has its own URL and can serve traffic

D Only if manually enabled

Each deployment slot has its own hostname and can serve traffic independently.

Explain how deployment slots help achieve zero downtime during app updates.

Think about how swapping slots affects live users.

Describe the difference between slot-specific settings and swapped content in deployment slots.

Consider what changes and what stays the same after a swap.

Practice

1. What is the main purpose of using deployment slots in Azure App Service?

easy

A. To create multiple independent apps with separate resources

B. To test new app versions safely before making them live

C. To increase the storage capacity of the app

D. To backup the app data automatically

Solution

1. Step 1: Understand deployment slots purpose

   Deployment slots allow you to deploy a new version of your app in a separate slot to test it without affecting the live app.

2. Step 2: Compare options with deployment slots function

   Options A, B, and D describe unrelated features like independent apps, storage, or backups, which are not the main purpose of deployment slots.

3. Final Answer:

   To test new app versions safely before making them live -> Option B

4. Quick Check:

   Deployment slots = safe testing before live [OK]

Hint: Deployment slots = safe app version testing before live [OK]

Common Mistakes:

• Thinking slots increase storage
• Confusing slots with separate apps
• Assuming slots are for backups

2. Which of the following is the correct way to swap a staging slot with the production slot in Azure CLI?

easy

A. az webapp deployment swap --name MyApp --resource-group MyGroup --slot staging

B. az webapp slot swap --name MyApp --resource-group MyGroup --slot production

C. az webapp deployment slot swap --name MyApp --resource-group MyGroup --slot staging

D. az webapp deployment slot switch --name MyApp --resource-group MyGroup --slot staging

Solution

1. Step 1: Identify correct Azure CLI command syntax

   The correct command to swap deployment slots is az webapp deployment slot swap with parameters for app name, resource group, and slot.

2. Step 2: Check each option's command correctness

   az webapp deployment slot swap --name MyApp --resource-group MyGroup --slot staging matches the correct syntax exactly. Options B, C, and D have incorrect command names or parameters.

3. Final Answer:

   az webapp deployment slot swap --name MyApp --resource-group MyGroup --slot staging -> Option C

4. Quick Check:

   Correct CLI swap command = az webapp deployment slot swap --name MyApp --resource-group MyGroup --slot staging [OK]

Hint: Use 'az webapp deployment slot swap' with --slot staging [OK]

Common Mistakes:

• Using 'slot swap' instead of 'deployment slot swap'
• Swapping with production slot explicitly
• Misspelling 'deployment' or 'swap'

3. Given the following Azure App Service slots setup:

Production slot URL: https://myapp.azurewebsites.net
Staging slot URL: https://myapp-staging.azurewebsites.net

If you deploy a new version to the staging slot and then swap slots, what will be the URL of the new live app?

medium

A. https://myapp-staging.azurewebsites.net

B. https://myapp-live.azurewebsites.net

C. https://myapp-staging-live.azurewebsites.net

D. https://myapp.azurewebsites.net

Solution

1. Step 1: Understand slot URLs and swapping behavior

   Each slot has its own URL. When you swap staging with production, the staging app becomes live at the production URL.

2. Step 2: Identify the live app URL after swap

   After swapping, the new live app runs at the production slot URL https://myapp.azurewebsites.net. The staging URL remains for the old production app now in staging.

3. Final Answer:

   https://myapp.azurewebsites.net -> Option D

4. Quick Check:

   Swap keeps live URL as production slot URL [OK]

Hint: Live app URL stays production slot URL after swap [OK]

Common Mistakes:

• Assuming staging URL becomes live URL
• Thinking swap creates new URLs
• Confusing slot names with URLs

4. You tried to swap your staging slot with production but received an error saying the swap failed due to configuration conflicts. What is the most likely cause?

medium

A. The staging slot has app settings marked as 'slot setting' that differ from production

B. The staging slot is using a different Azure subscription

C. The production slot is stopped and cannot be swapped

D. The staging slot has no deployment

Solution

1. Step 1: Understand slot setting behavior during swap

   App settings marked as 'slot setting' stay with their slot and do not swap. Conflicts arise if these settings differ between slots.

2. Step 2: Analyze error cause possibilities

   The staging slot has app settings marked as 'slot setting' that differ from production explains configuration conflicts due to slot settings. Options B, C, and D do not cause swap configuration conflicts.

3. Final Answer:

   The staging slot has app settings marked as 'slot setting' that differ from production -> Option A

4. Quick Check:

   Slot setting conflicts cause swap errors [OK]

Hint: Check 'slot setting' app settings for conflicts before swap [OK]

Common Mistakes:

• Ignoring slot setting app configuration
• Assuming subscription mismatch causes swap errors
• Trying to swap when production is stopped

5. You want to minimize downtime during a major app update using deployment slots. Which strategy best achieves this?

hard

A. Deploy the new version to a staging slot, test it, then swap with production slot

B. Deploy directly to production slot during off-hours without staging

C. Create a new app service and switch DNS to it after deployment

D. Stop the production slot, deploy update, then start it again

Solution

1. Step 1: Understand deployment slots for zero downtime

   Deployment slots allow deploying and testing new versions without affecting live traffic, then swapping instantly to minimize downtime.

2. Step 2: Evaluate each strategy for downtime impact

   Deploy the new version to a staging slot, test it, then swap with production slot uses deployment slots correctly. Options A, B, and C cause downtime or complex DNS changes.

3. Final Answer:

   Deploy the new version to a staging slot, test it, then swap with production slot -> Option A

4. Quick Check:

   Use staging slot deployment and swap for minimal downtime [OK]

Hint: Deploy to staging slot, test, then swap to production [OK]

Common Mistakes:

• Deploying directly to production causing downtime
• Using DNS switch instead of slot swap
• Stopping production slot during update