Docker

Dockerfile

File named dockerfile with no file extension that contains instructions for building the image.

Help

run docker to see a list of commands. Then docker <command> --help to get help on individual commands.

Pull to pull an image or build to build from a dockerfile

• docker pull mcr.microsoft.com/powershell:lts-debian-10
  • pulls image mcr.microsoft.com/powershell with tag lts-debian-10
• docker build -t linux-powershell .
  • builds from dockerfile in current folder (".") and tags with linux-powershell.
• using a file not named dockerfile can be done with -file
  • docker build -f mydockerfile .

This generates an image. Then it needs to be Run or Created to get a container which can then be started.

Run to create and start or start to just start an existing containter

• docker run -it --name linux-powershell linux-powershell
  • creates and starts a docker container based on given image, names it linux-powershell and sets it to interactive so standard in/out is written from/to console.
  • can also be a remote image: docker run -it --name linux-powershell mcr.microsoft.com/powershell:lts-debian-10
  • use docker create instead to split and allow for docker start afterwards
• docker start -i linux-powershell
  • starts the container mentioned above.

Common issues

• Sometimes updated files used in COPY doesn't update inside container when rebuild. In that case it might help to build with --no-cache:
  • docker build --no-cache
• Connecting to something on the host machine can be done with host.docker.internal on windows and linux systems
• Can't easily use kerberos/ad from inside docker

See also rancher