If I have two Docker instances, with a common base image containing e.g. libc.so, then will those two instances share libc's memory? When Docker moves from AUFS to BtrFS, will it share the memory there also?
Edit: I ask because the idea of getting 100-1000 instances on a single machine is attractive, but seems like it might be difficult to achieve in reality...
Would docker be well suited for a testing platform? Thinking about maybe using docker to stand up a database instance that can be instantiated quickly and blown away after test cases are executed, seems like it would be a perfect use case for something like docker since manually restoring a db backup for testing can take several minutes.
It's also great for testing clusters on a single VM. I've been using it for playing around with different mongodb configurations. Being able to instantly start, stop, and fork server images is pretty amazing. Also very nice being able to replay commands from the cache, so downloading and building a bunch of packages only has to work once. It doesn't do anything that you couldn't do with virtual machines or ec2 images, it's just so much faster and lighter weight it's kind of like the difference between having to compile your code after every change and having live reload. Much better for your productivity.
Yes, it would be perfect for that. In fact people are using it for that today.
Here are some slides showing how eBay does this today with Docker. https://speakerdeck.com/teddziuba/docker-at-ebay there is also a video available of the talk he gave explaining it at one of the docker hack days. I don't have the link handy, but I'm sure you could find it.
Edit: I ask because the idea of getting 100-1000 instances on a single machine is attractive, but seems like it might be difficult to achieve in reality...