Do you do a
git pullinsideDockerfile?
No, that’s not really how Docker containers work. The basic idea is that you, as the application developer, write a Dockerfile which describes how to build, configure and start your application. You then use this Dockerfile to build a Docker image (through the docker build command). This image is a bit like a small virtual machine with your application and its dependencies baked in. Finally, you push your image to some repository and ask your cloud provider to deploy this image to a server.
The goal behind this is that images provide a reproducible deployment environment that is built from scratch every time. This means you can take your image and deploy it as many times as you want, on any server you want from any provider you want and it should work the same every single time. This is in contradiction to VPS-based deployments, where you have a single server that you configure manually and push updates to, which often ends up with the server holding all sorts of hidden dependencies and configurations that can be extremely hard to reproduce if you ever need to migrate or scale to another server.
Now, because we want reproducible builds from scratch, updating the application usually means building a whole new image with our updated code and deploying that new image to replace the old one. The exact way to do this will depend on the service you’re using to host your app.
With all that said, I’d recommend you avoid deploying to AWS if you can. AWS is a very complex system that’s more tailored to bigger teams or experienced developers who want fine-grained control over their infrastructure. Because of that, their documentation is honestly pretty hard to follow if you don’t already kind of know what you’re doing.
I’d recommend looking at smaller infrastructure providers with more focused and beginner-friendly offerings. fly.io is very popular in the elixir community for very good reason imo. They have a dedicated guide for Elixir (although the deployment process is basically the same as with any other stack) and it lets you deploy and update an app with just a couple of commands.
