You can limit file system access for the server to only a certain folder.
You can similarly limit port access and manage conflicts (e.g. multiple servers can think they are listening on a certain open port but those are mapped to something else on the host).
If you have multiple machines with different operating systems or even architecture you can deploy your server as a container more easily on them without needing to rebuild or test for each one.
You can have the same environment running locally while development or on CI servers without complicated setups.
The system can scale out a lot more easily to hundreds/thousands of machines if you decide to use something like Kubernetes.
The ability to pull the image on to any machine without needing to clone the source files and build it.
Smaller images mean faster pod starts when you auto scale.
What kind of work are you doing that requires really fast auto scaling? Is a few minutes to spin up a new instance really that cumbersome? Can you not signal for it to spin up a new instance a tiny bit earlier than when it's needed when you see traffic increases?
In isolation, yes. But if, for instance, you're already running a container orchestration tool with hundreds of containers, and have CI/CD pipelines already set up to do all of that, it's easier just to tack on another container.
Which seems like sort of an edge case for value adding, and makes me feel like it really doesn't add any value to do this unless you already are doing it for everything, and thus you really wouldn't be throwing out any value by just serving the static site without the docker overhead.
Anything else, though? There’s got to be more to it than that, or it wouldn’t be as popular as it is.
