docker

• daemon must be running (systemctl start docker)
• use sudo or add user to group docker (sudo usermod -aG docker user)
• docs
• there are lots of flavours and tools upon tools, each w/ their own name, currently (sept 2018) "docker" usually means "docker ce (community edition)"
• images are built, containers are running images, aka images w/ command (like class vs instance) (not sure if this is correct, but get the idea)

hello world

docker version
docker info
docker pull hello-world
docker image ls -a
docker container ls -a
docker run hello-world
docker ps                   # list running container
docker top <container>      # pipes internal top
docker rm <container>
docker rmi <images>
docker rm -f $(docker ps -a -q) # stop and remove all
docker run -it ubuntu bash      # start image
docker exec -it <container> sh  # give interacive shell in running container
docker logs <container>         # show stdout/stderr (?) of running processes
docker system prune -a          # `--all` includes images

dockerfile

• order sensitive
• every line is some delta-foo
• gets images from hub, or local repository
• minimal image is named "scratch" (FROM scratch)
• minimal userland image is "alpine", which is a minimal linux distro
• naming convention for images: --
• ENTRYPOINT: hard-coded command and args to run, sometimes empty, overwrite w/ --entrypoint
• CMD: default args, overwritten by args passed to docker run

file lives in own dir, build w/:

docker build <dirname>
docker build <dirname> -t <name>:<tag>
docker history <image>

docker compose

configures one or more docker containers and one or more networks. images are usually referenced by their name:tag given on build w/ -t. can handle multiple containers in multiple networks and up/down them all in one go.

all before : is host, all after is in docker.

docker-compose up
docker-compose down     # all data inside container will be lost
docker-compose pause    # data will be retained, will be resumed on host reboot
docker-compose unpause <id>
docker-compose ps       # like `docker ps`, but with grouping
docker-compose logs
docker-compose run <id> bash    # interactive shell using docker-compose settings

storage

julian says: also check named volumes in gitea doc.

• volumes: are stored in docker-managed part of fs, e.g. /var/lib/docker/volumes/, see docker volume create/ls/prune/...
• bind mounts: anywhere on fs, may be modified by anyone at anytime
• tmpfs mounts

history / buzzwording

• kernel namespaces
• cgroups, grep "docker\|lxc" /proc/1/cgroup
• sdn, software defined network (maybe not lxc), can alias names
• lxc, first container implementation by kernel devs
• docker, pimped lxc