docker

environment variables

• add environment variables to run command with -e argument.

docker run -e APP_COLOR=green simple-webapp-color

dockerfile entrypoint and cmd

• entrypoint is used when you want to pass additional arguments

  ENTRYPOINT ["sleep"]
  

• cmd is used to pass argument when you have entrypoint

  ENTRYPOINT ["sleep"]
  CMD ["5"]
  

• can override entrypoint with --entrypoint argument when running image

network

• none container cannot reach outside and cannot be reached complete isolation
• host container attached to host network no network isolation
• bridge docker creates internal network for attaching containers
  • on host interface created with docker0 name
• list networks with docker network ls
• docker creates network namespace for each container