1. docker build incantations
    2. command / prompt description
    docker build --network host --progress=plain -t <tag name> . build using the Dockerfile in the current dir. The --progress=plain part of the incantation supprisingly produces way more verbose output.
  2. other incantations
    3. command / prompt description
    docker run -it --entrypoint=sh <image> start up a container but supply a different entrypoint. This has the effect of not executing the CMD supplied in the Dockerfile and is very useful for debugging. In other words, it can be used to override CMD when running a Docker image.
    docker run -d -p 8081:80 --name <container-name> --env-file .env -e X=Y <image-name> start up container in detached mode, map its local port 80 to the host's port 8081, give it the name foo-cont and pass tt environment variables from the .env file overriding env variable X with the value Y
    docker exec -it <container_name> sh open a shell into a running container (more)
    docker image ls list all docker images
    docker image rm removes an image from the host node — alias docker rmi
    docker rmi $(docker images -a -q) remove all locally installed Docker images
    docker image prune removes all dangling images (those with tag none). The -a option would also remove images that have no container
    docker ps -a list all containers, including the stopped ones — alias: docker container ls -(l)a
    docker container prune remove stopped containers
    docker logs container_id can be either the name or the identifier of the container. You can also use -f to follow
    systemctl status docker check the status of the docker deamon
    pgrep docker find the PID of the docker deamon
    /var/lib/docker where are docker containers stored
  3. SO answers
  4. some docker tutorials
  5. some docker cheatsheets
  6. how to build the docker image and run the container for Kartoza GeoServer image

    7. To test locally, on port 8081, with your own supplied username / password do: 

    $ docker build --network host -t lpis_geospatial_server .
$ docker run -d -p 8081:8080 --name lpis_geo -e GEOSERVER_ADMIN_USER=changeme -e GEOSERVER_ADMIN_PASSWORD=changeme lpis_geospatial_server
    The above runs the container in detached mode (-d) and exposes the GeoServer at t doche localhost:8081/geoserver/web URL. It is also possible to open an interactive shell to the GeoServer container constructed above by doing, as usual: 
    docker exec -it lpis_geo sh
    Once inside (i.e. in a shell in the running container) you can do: 
    curl -L -b cookies.txt -c cookies.txt localhost:8080/geoserver/web -o geoserver.html
    to fetch the geoserver home page or use ss -tulnp to confirm the port being listened to.

  7. how to build the docker image and run the container for IACS'24'COGN

    1. cd into the /iacs-ui.24.cognitera/frontend directory so that you have the Dockerfile in the current directory
    2. Make sure the user is in the docker group (see the entry below)
    3. build the docker image with the --network host option and supply a plausible name:
      $ docker build --network host -t iacs-ui.24.cogn:v1 .
    4. if you want to keep and perhaps examine the logs of the docker build process use the following in lieu of the above command:
      docker build --no-cache --progress=plain --network host -t iacs-ui.24.cogn:v1 . 2>&1 | tee docker-build.log
    5. run the image by mapping port 8080 to its 8000 port (alternatively use the -P option), pass an environment variables file into the container and also supply a short reasonable name for the container (e.g. iacs in the incantation below): 
      $ docker run -d -p 8090:8000 --env-file=.env --name iacs iacs-ui.24.cogn:v1
    6. verify the ports the web application being hosted inside the container is listening on: 
      $ docker port iacs
8000/tcp -> 0.0.0.0:8080
8000/tcp -> [::]:8080
    7. connect your browser to localhost:8080
    8. to "ssh" (sort of) into the container you cannot use docker attach but you must instead use docker exec as follows (see this SO answer for more): 
      docker exec -it iacs sh
    9. once you are done, stop the container using docker stop iacs — there's no need to do docker container prune to remove the stopped container as the image was run with the -d option in step 4
  8. permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock

    9. provenance
    The user that is running the docker commands (if he is a non-root user) must be added in the docker group. This is done with the following incantation: 

    sudo usermode -aG docker $USER
    … but only takes effect after a system reboot. In the meantime you can use newgrp docker in the shell you're working (this will result in a new shell with the current user being part of the docker group).

  9. [Errno 101] Network is unreachable

    10. In November 2024 when going through this docker beginners tutorial (also saved here) I encountered this trace:

    In the end I had to change the docker build invocation from: 

    docker build . -t mperdikeas/catnip
    to: 
    docker build . --network host -t mperdikeas/catnip

    In initially commented on an already existing bug report and then reported my solution here.

    The solution was found in this thread which also reports at least one additional approach.

    See also this ChatGPT thread of mine.