Why do we need Docker? Why can't we just run a binary on the server?

Docker is used to create isolated, reproducible, and portable environments for running applications. You can run a simple binary on a server, but then:

• Dependencies and environment may differ, leading to errors.
• It's hard to guarantee the same behavior across different machines.
• Scaling and managing applications is difficult.

Docker packages the application along with all its dependencies and configurations into a container, which can be run on any machine with Docker, ensuring consistency and ease of deployment.

Example: if you have a Go service that depends on a specific database version and settings, a Docker container guarantees that everything will work the same everywhere.