How to Deploy Azure Container Apps Updates Without Downtime?

AZ-204 By islever Editorial Last updated

Implement containerized solutions

Short answer

A Enable single revision mode so Azure Container Apps keeps the current revision serving 100% of ingress traffic until the updated revision is ready.

Question

You are developing a microservice to run on Azure Container Apps for a company. External HTTP ingress traffic has been enabled. The company requires that updates to the microservice must not cause downtime. You need to deploy an update to the microservices. What should you do?
  1. Enable single revision mode. Correct Answer
  2. Use multiple environments for each container.
  3. Use a private container registry and single image for all containers.
  4. Use a single environment for all containers.
  5. Enable multiple revision mode.

Key Takeaways

This item tests Azure Container Apps revision behavior for zero-downtime updates, and the trap is choosing multiple revision mode because it sounds like canary deployment is required.

Azure Container Apps zero-downtime deployments depend on revision mode. Single revision mode is the documented setting that keeps the current revision serving ingress traffic until the updated revision is ready.

Common mistake: The most common wrong answer is E, multiple revision mode, because learners assume traffic splitting is necessary for no-downtime updates; single revision mode already provides the documented zero-downtime replacement.

Expert Analysis

Why the Answer Is Correct

The question's only hard requirement is that a microservice update on Azure Container Apps must not cause downtime. Microsoft's revision documentation states that in single revision mode, Container Apps keeps the existing active revision alive and, when ingress is enabled, continues routing 100% of traffic to it until the new revision is ready. Therefore enabling single revision mode is the direct, documented mechanism that satisfies "updates must not cause downtime." This matches the more useful community answers: AzDeveloper cites the zero-downtime deployment doc, and Sachin39 notes that "continues to receive 100% of the traffic until the new revision is ready" describes the single-revision behavior. NewChampion also summarizes simply that "Single Revision Mode has zero downtime."

Why the Other Options Are Wrong

B and D are wrong because environments in Azure Container Apps are boundaries for a group of container apps, not a deployment mechanism for a single microservice update; creating multiple environments does not provide zero-downtime revisions. C is wrong because a private registry or a single image is a supply-chain/image-management choice and does not control whether an update replaces a running revision without interruption. E is the tempting but incorrect choice: multiple revision mode is useful for traffic splitting, canary releases, and A/B testing, but the question does not require gradual traffic control, and Microsoft explicitly documents zero-downtime deployment for single revision mode. As Kvadraciuks argues, multiple revision mode can support zero downtime, but that does not make it the required answer for a plain no-downtime scenario.

Community Comment Notes

The comment section is split: several learners, including Kvadraciuks, Ciupaz, Iaminall, and VithobaS, pick multiple revision mode because they associate traffic splitting with zero downtime. Their reasoning is understandable but goes beyond the question's requirement; traffic splitting is an advanced rollout pattern, not the documented zero-downtime requirement. AzDeveloper, Sachin39, Circle089, and NewChampion point back to the Azure Container Apps revisions doc, with NewChampion stating "Single Revision Mode has zero downtime" and Sachin39 quoting the key guarantee about the active revision continuing to serve 100% of traffic. 5691024 notes that the docs say both modes can avoid downtime, but then adds a valid concern about validating a broken revision; that concern is about release safety, not about the exam's explicit must-not-cause-downtime requirement. Overall, the official documentation and the better-supported comments favor A.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

Memorize the subtle distinction: Azure Container Apps single revision mode provides zero-downtime deployments by keeping the active revision alive until the new revision passes readiness, while multiple revision mode adds traffic splitting and A/B testing. On the exam, when the requirement is only no downtime during an update, choose single revision mode unless the question also asks for canary or gradual traffic control.

Frequently Asked Questions

Why isn't multiple revision mode the correct answer for zero downtime?

Multiple revision mode enables traffic splitting and canary testing, but single revision mode is the documented Azure Container Apps zero-downtime deployment mechanism.

Does external HTTP ingress change which revision mode I should choose?

No. With ingress enabled, single revision mode keeps the existing revision serving 100% of traffic until the new revision is ready, which is exactly the zero-downtime behavior required.

More AZ-204 FAQ →

Community Votes

A
62%
E
38%

62% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 15 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 15

  1. AzDeveloper 👍 12 Answered A
    Zero downtime deployment using single mode https://learn.microsoft.com/en-us/azure/container-apps/revisions#zero-downtime-deployment
  2. Sachin39 👍 4 Answered A
    In single revision mode, Container Apps ensures your app doesn't experience downtime when creating a new revision. The existing active revision isn't deactivated until the new revision is ready. If ingress is enabled, the existing revision continues to receive 100% of the traffic until the new revision is ready. https://learn.microsoft.com/en-us/azure/container-apps/revisions
  3. Kvadraciuks 👍 4 Answered E
    E. Enable multiple revision mode: Multiple revision mode allows for more than one version of the container app to be active at the same time. This is essential for zero-downtime deployments because you can deploy a new revision without taking down the old one, then gradually shift traffic to the new revision using traffic splitting.
  4. 5691024 👍 3 Answered E
    My guess is E? The docs are very clear that both Single- and Multi-Revision are zero-downtime: https://learn.microsoft.com/en-us/azure/container-apps/revisions#zero-downtime-deployment ...so there's no clear answer just from that. My thinking is: Even if the container ready-checks pass, the deployed code itself could still be flawed and result in a broken application. Being able to validate the new version using multi-revision mode is a safer option than just sending it. Is a broken app technically 'downtime'? Debatable. Should a broken app be caught before the prod deploy? Certainly. But I don't see any other way to favour one option over the other. Of course, is that what Mr. Microsoft wants...? I have no idea.
  5. Ciupaz 👍 3 Answered E
    Wrong. Should be multiple revision mode.
Show 10 more comments
  1. manopeydakon 👍 2
    E. Enable multiple revision mode. Explanation: Azure Container Apps supports multiple revision mode, allowing you to deploy updates without causing downtime. With multiple revision mode, you can deploy new revisions of your microservice while keeping the previous revision running. This approach enables a smooth transition without interruption to your application. So, choose option E to enable multiple revision mode when deploying updates to your microservice on Azure Container Apps.
  2. Circle089 👍 2 Answered A
    https://learn.microsoft.com/en-us/azure/container-apps/revisions#zero-downtime-deployment
  3. ciamp 👍 1
    E Single Revision Mode: In single revision mode, only one revision of the application is active at any given time. When you deploy a new revision, it replaces the current active revision. This means that during the deployment process, the old revision is taken offline while the new one is brought up. This can cause a brief period where the application might be unavailable or not fully functional, resulting in potential downtime. Multiple Revision Mode: This mode allows multiple revisions to run concurrently. When deploying a new revision, it can coexist with the old revision. Traffic can be routed gradually from the old revision to the new one, ensuring a smooth transition without downtime.
  4. AlpeshD 👍 1 Answered A
    https://www.google.co.nz/search?q=which+revision+mode+in+azure+for+zero+downtime&safe=active&sca_esv=596418299&ei=yyObZa-sM9GYseMP2IOmqA0&ved=0ahUKEwjvvdT3p8yDAxVRTGwGHdiBCdUQ4dUDCBA&uact=5&oq=which+revision+mode+in+azure+for+zero+downtime&gs_lp=Egxnd3Mtd2l6LXNlcnAiLndoaWNoIHJldmlzaW9uIG1vZGUgaW4gYXp1cmUgZm9yIHplcm8gZG93bnRpbWUyBxAhGAoYoAFI8k5QlApYhE5wCHgBkAECmAGNBqAB_0WqAQ0yLTEzLjExLjEuMS4xuAEDyAEA-AEBwgIKEAAYRxjWBBiwA8ICBRAhGKABwgIEECEYFeIDBBgAIEGIBgGQBgg&sclient=gws-wiz-serp
  5. VithobaS 👍 1 Answered E
    Multiple Revision Mode: - In multiple revision mode, Azure Container Apps creates a new revision each time a deployment is updated. - Traffic can be split between the current and new revisions during the update process, ensuring zero downtime. - Once the new revision is stable, traffic can be shifted fully to the new revision, completing the update.
  6. Dkijc 👍 1
    A Source: https://learn.microsoft.com/en-us/azure/container-apps/revisions#zero-downtime-deployment
  7. NewChampion 👍 1 Answered A
    Single Revision Mode has zero downtime.
  8. Iaminall 👍 1 Answered E
    Enable multiple revision mode.
  9. Iaminall 👍 1 Answered E
    E is the correct one.
  10. azpardha 👍 1 Answered A
    single revision mode

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