Can someone explain what I can use docker for? For example could I create a web app with docker, and send that docker image as the product? How could I update the image remotely when it's running somewhere out there?
Docker doesn't let you push updates to containers. I think the best you can do is to push a new image to your registry and ask your customers to pull and fire up new containers.
Building them is extremely quick as intermediate build results are cached, and moving them about is similarly fast as I only have to push around diffs.
This isn't to say that containers are better than VMs, just that they're better for what I'm doing.
> I get the instant on part but have yet to see a compelling use case that goes for container over VM.
Looking at it the other way, what are the compelling reasons to go for VMs over containers? If they don't apply for your use case, then why not have something lighter and faster?