What is Docker?

• 1. (nice intro article at: https://www.jayway.com/2015/03/21/a-not-very-short-introduction-to-docker/)
  2. Java's promise: Write Code Once. Run Anywhere
  3. Docker’s promise: Configure Runtime Once (per image). Run it Anywhere
     1. Instead of code, you can configure your runtime exactly the way you want them (pick the OS, tune the config files, install binaries, etc.) and you can be certain that your runtime template will run exactly the same on any host that runs a Docker server.
     2. Docker’s collaboration features (docker push and docker pull) are one of the most disruptive parts of Docker. The fact that any Docker image can run on any machine running Docker is amazing. But The Docker pull/push are the first time developers and ops guys have ever been able to easily collaborate quickly on building infrastructure together. The developers can focus on building great applications and the ops guys can focus on building perfect service containers. The app guys can share app containers with ops guys and the ops guys can share MySQL and PosgreSQL and Redis servers with app guys.
     3. This is the game changer with Docker. That is why Docker is changing the face of development for our generation. The Docker community is already curating and cultivating generic service containers that anyone can use as starting points. The fact that you can use these Docker containers on any system that runs the Docker server is an incredible feat of engineering.

• Docker utilizes container handling features built into Linux & Windows Server 2016

  1. On Mac or PC, we need a Linux Virtual Box machine to access these capabilities
• Container model is much more efficient than virtual machine model for achieving better resource utilization and portability
  1. Operating System/Kernel - Docker-Machine (gives us a lightweight linux VM)
  2. “Container Engine” - Docker Daemon/Server/Engine - Supports multiple containers. One engine per docker-machine
  3. Containers - Each container can have its own runtime environment. Multiple containers OK
  4. Swarm - multiple Docker-Machines, each w/1 docker-engine. Each docker-engine can have multiple containers.