In our company, we have an internal application that utilizes MongoDB. The application consists of multiple microservices, each interacting with its own MongoDB instance. While the application doesn’t experience heavy loads, it’s critical for our business, so we need it to be resilient. Creating multiple MongoDB instances for each service seemed impractical and costly. Therefore, we opted for a unified resilient MongoDB cluster. Since we currently don’t require sharding, we’ll only be using MongoDB replicas. In this article, I’ll describe how I set up replicas in AWS using Docker and how we use them in our application.

When we build a Docker image of our application, we already know which version of the application will be in it. But often we don’t bother passing this information inside the container. Especially when it comes to web applications. However, this can be useful. For example, for error monitoring, it will definitely be helpful to know which version of the application crashed and when it was built.

In this article, I’ll explain how to pass information about the application version inside the container. This applies to applications in Go as well as web applications in Node.js. I’ll also show how to use this information inside the container.