I'm curious about why Docker images, like the MySQL image, are so much lighter compared to traditional software installations on systems like Windows 10. Docker images are OS-specific, and while I understand that the MySQL Docker image operates on Windows resources and makes Windows API calls, it seems like the Docker image still manages to be significantly smaller. What exactly makes Docker images more lightweight compared to a full installation that includes a lot more files and components?
4 Answers
A lot of unnecessary components get trimmed away in Docker images. They only include what's needed to run the application, discarding extras like binaries that aren't essential, or anything related to shell completion. This optimization contributes significantly to their smaller size.
Docker images typically use a stripped-down version of Linux, which is inherently smaller compared to the full Windows installation. When you install something like MySQL on Windows, you're getting a lot of extra baggage: a GUI, multiple DLLs, and other dependencies that make it bulky. In contrast, the Linux version is designed to run from the command line without any GUI, which means it can focus purely on the essentials, making it much lighter.
Exactly! Docker images are all about containing only what's necessary to run the application, unlike a full VM that has to have a complete OS. If you're running Linux containers on Windows, there's extra overhead because of the virtual Linux layer involved, which is something to keep in mind.
The majority of available Docker images, like MySQL, are built on Linux, which is what makes them smaller. There isn't a Windows-based MySQL Docker image because Docker was originally developed for Linux. While there are some creative workarounds for Windows, those images typically take up more space—often resembling a full Windows installation rather than a lightweight package.
Technically, there isn't a straightforward 'Docker for Windows' because it operates through a Linux virtual machine on Windows. So, the Docker images you see are primarily Linux-based, which is a significant factor in their size difference when compared to Windows installations.
You might be surprised, but Windows containers have been around for a while! Still, the predominant Docker experience is indeed rooted in Linux.
That's right! Plus, I mainly use Alpine as my base for Docker images, and it keeps things super slim at around 40MB. On the other hand, some people opt for full Ubuntu builds and end up with images over 400MB, which really adds up if you have a bunch of them.