Building and deploying container applications

On and off over the last few months, I have spent a considerable amount of time working to create a miniature version of what could be a production system at home. The goal, at least in this first phase, is to create an API which supports containerized deployment and a build and deploy pipeline to move this application through the various states of development (in my case, development, staging, and production).

The Tools

I chose tools that are currently being used (or may be used) at work to allow my research to be utilized in multiple areas, and it has allowed me to dive into a lot of new technologies and understand how everything works together.

  • Teamcity – I utilize TeamCity for building the API code and producing the necessary artifacts. In this case, the artifacts are docker images. Certainly, Jenkins or another build pipeline could be used here.
  • Octopus Deploy – This is the go-to deployment application for the Windows Server based applications at my current company, so I decided to utilize it to roll out the images to their respective container servers. It supports both Windows and Linux servers.
  • Proget/Docker Registry – I have an instance of ProGet which houses my internal nuget packages, and was hoping to use a repository feed to house my docker images. Alas, it doesn’t support Docker Registries properly, so I ended up standing up an instance of the Docker Registry for my private images.

TeamCity and Docker

The easiest of all these steps was adding Docker support to my ASP.NET Core 2.2 Web API. I followed the examples on Docker’s web site, and had a Docker file in my repository in a few minutes.

From there, it was a matter of installing a TeamCity build agent on my internal Windows Docker Container server (windocker). Once this was done, I could use the Docker Runner plugin in TeamCity to build my docker image on windocker and then push it to my private repository.

Proget Registry and Octopus Deployment

This is where I ran into a snag. Originally, I created a repository on my ProGet server to house these images, and TeamCity had no problem pushing the images to the private repository. The ProGet registry feeds, however, don’t fully support the Docker API. Specifically, Octopus Deploy calls out the missing _catalog endpoint, which is required for selection of the images during release. I tried manually entering the values (which involved some guessing), but with the errors I ran into, I did not want to continue.

So I started following the instructions for deploying an instance of Docker Registry on my internal Linux Docker Container Server (docker). The documentation is very good, and I did not have any trouble until I tried to push a Windows image… I kept getting a 500 Internal Server Error with a blob unknown to registry error in the log. I came across this open issue regarding pushing windows images. As it turns out, I had to disable validation in order to get that to work. Once I figured out that the proper environmental variable was REGISTRY_VALIDATION_DISABLED=true (REGISTRY_VALIDATION_ENABLED=false didn’t work), I was able to push my Windows images to the registry.

Next Steps

With that done, I can now use Octopus to deploy and promote my docker images from development to staging to production. As seen in the image, my current network topology has matching container servers for both Windows and Linux, along with servers for internal systems (including running my TeamCity Server and Build Agents as well as the Docker Registry).

My current network topology

My next goal is to have the Octopus Deployment projects for my APIs create and deploy APIs in my instance. This will allow me to use an API management tool through all of my environments and provide a single source of documentation for these APIs. It will even allow me to expose my APIs for public usage, but with appropriate controls such as rate throttling and authentication.

I will be maintaining my infrastructure files and scripts in a public GitHub repository.