AWS App2Container is a command line tool that you can install on a server to automate the containerization of applications. This simplifies the process of migrating a single server to containers. But if you have a fleet of servers, the process of migrating all of them could be quite time-consuming. In this situation, you can automate the process using App2Container. You’ll then be able to leverage configuration management tools such as Chef, Ansible, or AWS Systems Manager. In this blog, we will illustrate an architecture to scale out App2Container, using AWS Systems Manager.

Why migrate to containers?

Organizations can move to secure, low-touch services with Containers on AWS. A container is a lightweight, standalone collection of software that includes everything needed to run an application. This can include code, runtime, system tools, system libraries, and settings. Containers provide logical isolation and will always run the same, regardless of the host environment.

If you are running a .NET application hosted on Windows Internet Information Server (IIS), when it reaches end of life (EOL) you have two options. Either migrate entire server platforms, or re-host websites on other hosting platforms. Both options require manual effort and are often too complex to implement for legacy workloads. Once workloads have been migrated, you must still perform costly ongoing patching and maintenance.

Modernize with AWS App2Container

Containers can be used for these legacy workloads via AWS App2Container. AWS App2Container is a command line interface (CLI) tool for modernizing .NET and Java applications into containerized applications. App2Container analyzes and builds an inventory of all applications running in virtual machines, on-premises, or in the cloud. App2Container reduces the need to migrate the entire server OS, and moves only the specific workloads needed.

After you select the application you want to containerize, App2Container does the following:

  • Packages the application artifact and identified dependencies into container images
  • Configures the network ports
  • Generates the infrastructure, Amazon Elastic Container Service (ECS) tasks, and Kubernetes pod definitions

App2Container has a specific set of steps and requirements you must follow to create container images:

  1. Create an Amazon Simple Storage Service (S3) bucket to store your artifacts generated from each server.
  2. Create an AWS Identity and Access Management (IAM) user that has access to the Amazon S3 buckets and a designated Amazon Elastic Container Registry (ECR).
  3. Deploy a worker node as an Amazon Elastic Compute Cloud (Amazon EC2) instance. This will include a compatible operating system, which will take the artifacts and convert them into containers.
  4. Install the App2Container agent on each server that you want to migrate.
  5. Run a set of commands on each server for each application that you want to convert into a container.
  6. Run the commands on your worker node to perform the containerization and deployment.

Following, we will introduce a way to automate App2Container to reduce the time needed to deploy and scale this functionality throughout your environment.

Scaling App2Container

AWS App2Container streamlines the process of containerizing applications on a single server. For each server you must install the App2Container agent, initialize it, run an inventory, and run an analysis. But you can save time when containerizing a fleet of machines by automation, using AWS Systems Manager. AWS Systems Manager enables you to create documents with a set of command line steps that can be applied to one or more servers.

App2Container also supports setting up a worker node that can consume the output of the App2Container analysis step. This can be deployed to the new containerized version of the applications. This allows you to follow the security best practice of least privilege. Only the worker node will have permissions to deploy containerized applications. The migrating servers will need permissions to write the analysis output into an S3 bucket.

Separate the App2Container process into two parts to use the worker node.

  • Analysis. This runs on the target server we are migrating. The results are output into S3.
  • Deployment. This runs on the worker node. It pushes the container image to Amazon ECR. It can deploy a running container to either Amazon ECS or Amazon Elastic Kubernetes Service (EKS).
Figure 1. App2Container scaling architecture overview

Figure 1. App2Container scaling architecture overview

Architectural walkthrough

As you can see in Figure 1, we need to set up an Amazon EC2 instance as the worker node, an S3 bucket for the analysis output, and two AWS Systems Manager documents. The first document is run on the target server. It will install App2Container and run the analysis steps. The second document is run on the worker node and handles the deployment of the container image.
The AWS Systems Manager targets one or many hosts, enabling you to run the analysis step in parallel for multiple servers. Results and artifacts such as files or .Net assembly code, are sent to the preconfigured Amazon S3 bucket for processing as shown in Figure 2.

Figure 2. Container migration target servers

Figure 2. Container migration target servers

After the artifacts have been generated, a second document can be run against the worker node. This scans all files in the Amazon S3 bucket, and workloads are automatically containerized. The resulting images are pushed to Amazon ECR, as shown in Figure 3.

Figure 3. Container migration conversion

Figure 3. Container migration conversion

When this process is completed, you can then choose how to deploy these images, using Amazon ECS and/or Amazon EKS. Once the images and deployments are tested and the migration is completed, target servers and migration factory resources can be safely decommissioned.

This architecture demonstrates an automated approach to containerizing .NET web applications. AWS Systems Manager is used for discovery, package creation, and posting to an Amazon S3 bucket. An EC2 instance converts the package into a container so it is ready to use. The final step is to push the converted container to a scalable container repository (Amazon ECR). This way it can easily be integrated into our container platforms (ECS and EKS).


This solution offers many benefits to migrating legacy .Net based websites directly to containers. This proposed architecture is powered by AWS App2Container and automates the tooling on many targets in a secure manner. It is important to keep in mind that every customer portfolio and application requirements are unique. Therefore, it’s essential to validate and review any migration plans with business and application owners. With the right planning, engagement, and implementation, you should have a smooth and rapid journey to AWS Containers.

If you have any questions, post your thoughts in the comments section.

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Categories: Architecture