Hey everyone, I've been diving deep into Docker over the last few weeks and feel pretty confident about most of it, but there's something that's still unclear to me: what does it mean when we talk about an "empty" Docker container? I'm referring specifically to containers created with a Dockerfile that uses `FROM scratch`. How does this differ from a typical container like one based on Ubuntu? Can someone explain what an empty container consists of?
3 Answers
You could think of scratch as an empty tarball. It's great for anyone who wants a clean slate for their container. For example, if you have static binaries, they can run in this empty container without additional overhead. It's a handy tool for certain workflows, especially when you want a highly optimized image.
Unlike an Ubuntu container, which comes with a bunch of pre-installed tools and a package manager, an empty container means you’ve got nothing pre-installed. You need to build everything from scratch, so it won't give you any Unix/Linux environment features unless you add them yourself.
Got it, so an empty container is basically starting from ground zero!
When you use `FROM scratch`, you're not actually creating a traditional image. Scratch is like a blank slate—it has literally zero bytes of data. So, an empty Docker container doesn't contain any files, libraries, or tools; it's just a completely empty filesystem. This can be useful for creating minimal images, especially if you're adding specific files or binaries that you need for your application.
Thanks for clarifying that! It makes sense as a way to create smaller, more efficient images.
That sounds super useful for streamlining images!