From charlesreid1

Docker is a way of deploying apps on servers. It packages apps into side-by-side containers. These are similar in spirit to virtual machines, but different because containers are not (or, don't have to be) fully bundled operating systems. The container system makes sure everything runs the same everywhere.

It's like Homebrew or Aptitude for apps.

Docker/Troubleshooting

Docker/Network Debugging

References

Docker's documentation is excellent: https://docs.docker.com/

Docker from the command line: https://docs.docker.com/engine/reference/commandline/cli/

Docker to run memcached (Digital Ocean guide): https://www.digitalocean.com/community/tutorials/docker-explained-how-to-create-docker-containers-running-memcached

Note that many Docker issues on Github contain a wealth of useful debugging strategies and commands for checking the state of networks, ports, etc. Example: https://github.com/docker/docker/issues/13914

Potential security issues with Docker containers: https://blog.docker.com/2013/08/containers-docker-how-secure-are-they/

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