Cloud Migration vs. Cloud Modernization: Which Approach Is Right for Your Workload?

So you’ve decided you want to move your application into the cloud to take advantage of benefits like scalability, reliability and the potential for cost savings. Now, you need to choose exactly how you’ll get your application into the cloud.

You have two main options: 

  • Cloud Migration
  • Cloud Modernization

Although each approach will result in an application that is hosted in the cloud, the processes behind cloud migration and cloud modernization vary significantly. As do the types of cloud environments you’ll end up with after completing cloud migration or cloud modernization. Depending on your goals and priorities, one approach is likely to be a better fit for your needs than the other.

Making the right decision about how to move an application into the cloud is important because it affects how much time, effort, and costs the migration process takes. It also determines which types of cloud services your app will depend on, how many resources your app consumes and how you manage your cloud-based app on an ongoing basis.

This article explains the differences between cloud migration and cloud modernization, as well as the pros and cons of each technique. You’ll learn which strategy is best for different use cases and what to expect when you’ve completed the process.

Cloud Migration 101

Before we get any further, what is cloud migration? Put simply, it’s the process of moving an on-premises application into the cloud without making changes to the architecture of the application.

You may need to make some configuration changes to your application, such as modifying it to run on a different operating system version, as a step in the cloud migration process. But you don’t change the fundamental nature of the application. You wouldn’t rewrite the app in a different programming language, for instance, or restructure its codebase in a major way.

Cloud migration is referred to as “lifting and shifting” because it involves taking an app that currently runs on-premises and “lifting” it into a cloud-based environment. 

Types of cloud migration

There are multiple types of cloud migration, including:

  • Public cloud migration, which happens when you migrate an on-prem app into the public cloud.
  • Private cloud migration, which involves moving an app into a private cloud. Your private cloud (and, by extension, the migrated app) might still be hosted on-premises. But after migration, the app is in a cloud.
  • Hybrid cloud migration, in which you move your app into some kind of hybrid cloud environment.

Thus, the type of cloud migration you perform depends on which type of cloud your app ends up moving into.

It’s also possible to migrate an application from one cloud to another, for example AWS to Microsoft Azure. This process is known as cloud-to-cloud migration, and it counts as one form of cloud migration. However, when people talk about cloud migration, they’re typically referring to moving an application into the cloud for the first time, not moving it to a different cloud.

Cloud migration example

To illustrate what cloud migration might look like in practice, consider an application with the following characteristics:

  • The application is a monolith that is executed by running the command /usr/bin/my-app.
  • The application is hosted on-premises using an Ubuntu 20.04 virtual machine.

Now, let’s imagine that we want to migrate this application into the AWS cloud. To do that, we’d need to complete the following steps:

  1. Identify which AWS service to use to host the app. AWS EC2 is an obvious choice in this case because EC2 lets you run virtual machines in the AWS cloud. Since the app is already running in a VM on-prem, moving it to a cloud-based VM is the simplest approach to achieving cloud migration.
  2. Set up the cloud environment. To do this, we’d create an AWS account and set up an EC2 instance that we will use to host the VM that hosts the app.
  3. Migrate the app. Migration is the step of actually moving the app into the cloud. There are two basic ways to go about migration in this scenario. One is to create an image of the on-prem VM and import the image into AWS. This approach is best if there are a lot of configuration details on the host VM that we want to preserve. Or, we could simply copy the application into a new VM. This approach is faster because it doesn’t require us to create and import a VM image; however, we may need to spend more time configuring the new VM to host the application.
  4. Configure IAM rules: In the cloud, we use Identity and Access Management (IAM) rules to govern who can do what with our resources. So, we’ll need to configure IAM policies that define who can run and modify the VM we’re using to host our cloud app.
  5. Configure backups: We’ll probably want to set up backups of our VM, so that we can recover it in case something goes wrong. We can do that using EC2 snapshots.
  6. Launch and test the app: Once the app (and its associated VM, if applicable) has been moved to the cloud and properly configured, we run it and validate it to make sure it operates as expected.
  7. Put the app in production: If all has gone well up to this step, we can put the application into production by redirecting application requests from the on-prem instance of the application to our new, cloud-based instance. We can then shut down the on-prem instance, since it’s no longer needed.

At the end of this process, we’ll have a cloud-based application that is very similar in most respects to the one we started. There are likely to be some minor differences. For instance, if we set up a new VM in EC2 to host the app, that VM could run a different operating system and be configured with different environment variables than the on-prem VM. The IAM rules and backup process for the cloud-based VM (and the app it hosts) will also look different from those that would be used on-prem.

As far as the application itself is concerned, however, it should be identical to the on-prem app. We haven’t changed the application during the migration process; we only changed the way that the application was hosted.

What is Cloud Modernization?

Cloud modernization is the process of updating or reframing applications to take full advantage of cloud-native architectures and cloud services.

For instance, when you perform cloud modernization, you might take a monolithic application and refactor it to use a microservices architecture. When the application is deployed as microservices, it can consume cloud hosting resources more efficiently. It is also easier to scale and update microservices, and to manage them using an orchestrator like Kubernetes. In each of these respects, a modernized app is able to take fuller advantage of the cloud than an app that is simply migrated to the cloud without any changes to the application itself.

Types of cloud modernization

There are three main types of cloud modernization:

  • Modernizing an on-prem app by overhauling it to take full advantage of the cloud, then moving it to the cloud.
  • Modernizing an app that is already hosted in the cloud, but that has not yet been optimized for the cloud.
  • Modernizing a legacy on-prem app and keeping it on-prem, but hosting it in a cloud-native on-prem environment (like a Kubernetes cluster).

Thus, cloud modernization doesn’t necessarily imply that applications move into the cloud. That may happen, but the applications could be in the cloud to begin with, or they could remain on-premises after modernization is complete. The defining characteristic of cloud migration is that applications are optimized for the cloud, rather than being moved into the cloud.

Cloud modernization example

As an example of cloud modernization in practice, consider the monolithic app that we discussed above in the context of cloud migration. As a reminder, that application is a monolith that runs inside an on-premises Ubuntu 20.04-based virtual machine.

To modernize the app, we’d follow a process that looks like this:

  1. Plan a new application architecture: We’d decide how to restructure the application so that it runs as a set of distributed microservices. We’d need to decide how many microservices to create and how to structure and organize them so that they encompass the application’s complete functionality.
  2. Refactor the application: Refactoring is the process of overhauling the application’s source code so that the app runs as microservices. This is usually the most time-consuming and effort-intensive part of cloud modernization.
  3. Build a new hosting environment: Because a microservices-based app uses a different deployment architecture than a monolith, we need to decide how we’ll host the modernized app. The most common approach would be to deploy each microservice in a container and manage them all using Kubernetes. But you might also choose to use serverless functions to host some parts of the application.
  4. Configure IAM: We need IAM policies to protect our refactored app.
  5. Plan backups: Backing up microservices is complicated and depends on how you host them. In a Kubernetes cluster, you could create backup images of each node, in addition to backing up the core Kubernetes hosting components, like etcd.
  6. Redeploy and test the app: With the updated deployment environment complete, we can deploy our application into it. We can then test it to make sure it works as it should.
  7. Put the app into production: If the application passes testing, we can put it into production by directing requests to it, and shut off the original, monolithic instance of the application.

At this point, we’ll have an application that is likely to run more reliably and efficiently using a cloud-native architecture than its monolithic predecessor.

Cloud modernization vs. cloud migration: The key differences

To sum up, the main differences between cloud migration and cloud modernization boil down to:

  • Time and effort: Cloud migration is a simpler process that requires less time and fewer resources.
  • Expertise required: Cloud migration doesn’t require development resources because there are no changes to make to the application. In contrast, cloud modernization requires major changes to application source code during the reframing process.
  • Resulting benefits: In general, cloud modernization provides more benefits because it results in apps that perform more reliably and cost-effectively in the cloud. Migrating an app to the cloud may also deliver some benefits, but the app won’t be as primed to take full advantage of a cloud hosting model or a distributed architecture.

So, ultimately, cloud migration is simpler, but cloud modernization delivers better long-term results. If you have the time and resources necessary to perform cloud modernization, it’s likely to be worth the effort. But if you just need to get your app into the cloud, cloud migration is the fastest way to do so.