What is Jessie Docker, exactly?

What does Alpine in Docker mean?

Alpine describes herself as: Small. Simple. Secure. Alpine Linux is a lightweight, security-oriented Linux distribution that uses musl libc/busybox.

You may also wonder, "How do I use Docker?" Docker method

1. 1 application = 1 can.
2. The process should be run in the foreground.
3. Data should be kept out of containers.
4. You should not use SSH. If you have to enter container, you can use docker exec.

Eventually, you might also wonder, "What is Jessie Linux?"

Debian releases > Debian Jessie. Jessie , the Debian 8 development codename, is Jessie . Jessie receives Long-Term-Support since 2018-06-17. Debian Stretch replaced it on 2017-06-17. It is currently the oldoldstable distribution.

What is GPG key for Docker?

GPG is the tool that secure apt uses to sign files and verify their signatures. This works only if the key server has been up. (See issue 13555 and "Key server timesout while installing docker on Ubuntu 14.04").