I'm curious, how exactly do Docker images work with the system? What's the logic behind layers, and what happens when you convert an image into a container? Can you explain this in general terms?
How do Docker images work?
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Docker images work just like compressed archive files; however, each layer stores a filesystem change. When converted into a container, these layers are combined and run—similar to Windows system restore points, where each layer is independent yet interconnected in its function.
Man, to understand how Docker images work, you first gotta wrap your head around the layer system, bro. Like, when I install an Nginx image, I see it’s actually a bunch of layers stacked on top of each other. Every command (like `apt install nginx`) creates a new layer, and Docker combines them to build the image. That’s why you can reuse layers—you make changes in an upper layer while keeping the ones below intact.
Then, when you convert it to a container, you’re basically taking a read-only copy of that image and adding a writable layer (the container layer) on top. So any changes the container makes while running (like creating files) stay in that top layer, and the image itself stays untouched. The biggest convenience for me is this: when you stop and delete a container, all those changes vanish, and the image stays clean. Once you get this, using Docker becomes way smoother.
Actually, I've come across Docker images quite a few times, but why layers are important has never been clear to me – how does this relate to performance?