What make Docker so popular and long-lasting?
- Container is essentially OS level virtualization. Each application gets illusion of its own OS, having almost absolute control over it. Another advantage is that host OS knows about the container processes and hence can share its resources among hosted containers.
- The concept of containers was started by FreeBSD, refined by Solaris and re-implemented by Linux.
- Containers are better than two other levels of virtualization:
- ABI/platform level, where application integrates with the platform (Google App Engine), doesn’t scale well.
- Hardware level, where a virtual hardware runs the OS (e.g. virtual machines, hypervisors).
- Docker containers run close to the real hardware, and host OS has knowledge of resource usage. Hence it’s an optimal sweet spot for virtualization.
- Joyent SmartOS is built on OpenSolaris and provides Solaris features to Linux like Docker containers. It acheives that by allowing Linux APIs translated to Solaris APIs. Everything runs on the bare metal hence.
- SmartOS containers get ZFS, Dtrace by default 🙂
- SmartOS containers are very secure as they run in zones.
I hope to cover Smart OS design internals, Docker container on Linux details in next posts.