Have you ever wondered during your cloud migration journey whether Azure Virtual Machines or Azure App service would best suit your workload requirements? In this article, we’ll take a deep dive into the advantages and disadvantages of using Azure Virtual Machines and Azure App Service. By discussing the key differences, drawbacks of these services, and benefits, you can make an educated decision on where to host your application. You can also read this Azure Virtual Machine vs Web App comparison cheat sheet to get an overview of their core differences.

Azure Virtual Machines

Advantages of Azure Virtual Machines:

1. Manageability: You have total control over the underlying operating system, custom configurations, and the ability to run custom software. 
2. Flexibility: Azure VMs enable you to have the flexibility of virtualization without having to procure and maintain your physical hardware. You can run any application regardless of its programming language, framework, or technology stack.
3. Familiarity: If you come from an on-premises setup and are new to Azure, you will have an easier time grasping the technicalities of Azure VM compared to other hosting options.

When to use Azure Virtual Machines:

1. Disaster recovery: You can easily protect your on-premises servers that would automatically failover to Azure by creating virtual machines and failback once your on-premises data center has resumed operations.
2. Development of applications: If you are testing a new application, you can quickly provision virtual machines and deploy your code. You can automatically shut down your development servers to save costs and delete them when you no longer need them.
3. Hybrid setup: If you run out of hardware in your on-premises data center, you can extend your network to Azure. You can deploy existing applications to Azure virtual machines to give you more flexibility regarding sizing. It is faster and cheaper to deploy than running them in an on-premises data center.

Disadvantages of Azure Virtual Machines:

1. Manageability: Although we listed the manageability of virtual machines as an advantage, some people may consider this a hindrance because it requires more hands-on management. Remember, with virtual machines, you take care of everything, such as maintaining the OS, updates, and software maintenance. This may be an easy task if you only have a few VMs, but it will be tedious if you have a fleet of them.
2. Potentially higher costs: Instead of focusing on building and maintaining your application, you must always consider your VMs manageability aspect. This results in higher costs as you need infrastructure engineers to concentrate on maintaining the VMs.

Azure App Service

Advantages of Azure App Service:

1. Simplified management: Microsoft Azure takes care of the underlying infrastructure allowing you to focus on your application.
2. Immediate deployment: App Service offers fast deployment and continuous integration with tools like Git, GitHub, and Azure DevOps.
3. Cost efficiency: A single App Service plan can contain multiple applications as long as the plan has enough resources to handle the increasing load.

Disadvantages of Azure App Service

1. Control: If you need specific controls over your infrastructure, then Azure VMs is your best choice. You only have a few options with Azure App service. 
2. Compatibility: App Service only offers specific languages. If you have a language not supported by App Service, VMs is your choice.
3. Potentially higher costs: If you need to upgrade a portion of your App tier, such as storage, you must upgrade to the next plan tier. This may result in higher costs and underutilized resources. 

In general, use Azure App Service if:

1. You’re totally fine with having less control over your infrastructure and settings.
2. You want to focus on developing your application and let Microsoft handle the infrastructure.
3. Azure App Service supports your application.
4. Your compute and storage requirement is a good match for the different App Service tiers.
5. You want to host multiple applications in a single App Service plan easily.