Di Lin's Blog
0%

Docker Toolkit

Posted on Edited on In ,

Docker Toolkit

Clean all container

1
2
docker stop $(docker ps -a -q)
docker rm $(docker ps -a -q)

Clean all

1
docker container stop $(docker container ls -a -q) && docker system prune -a -f --volumes

Remove all images except one

1
docker image prune -a --force --filter "label!=image_name"

Check disk usage

1
2
docker system df
docker system df -v

Enable docker CLI in WSL(with Docker for Windows installed)

  1. Tick the checkbox in docker setting:

    Expose docker daemon on tcp://localhost:2357 without TSL

  2. Install docker cli in WSL.

    apt-get install docker.io

  3. Expose tcp port in WSL.

    1
    2
    3
    4
    5
    docker -H tcp://0.0.0.0:2375 images
    echo "export DOCKER_HOST=tcp://localhost:2375" >> ~/.bashrc && source ~/.bashrc

    # If you are using zsh
    echo "export DOCKER_HOST=tcp://localhost:2375" >> ~/.zshrc && source ~/.zshrc

  4. Verify docker is enabled in WSL

    1
    docker --version

    Now you are using docker in WSL.

Dockerfile Optimization

Use this website to double check your Dockerfile.

Size of Docker Image

Docker image is compressed for faster download speed, and will be decompressed after being downloaded to your local machine.

The compressed size counts for the download time needed in certain development internet transmission environment, and the decompressed image size matters since it consumes local disk.

Actual Size of Docker Images

To get decompressed size of a docker image (i.e. the actual size), run the following command.

1
2
3
4
docker image ls

# or
docker system df -v

Compressed Size of Docker Images

To get compressed size of a docker image is more complicated.

  1. Get compressed image size information via Docker Hub Registry HTTP API v2.

    1. If the image is host on Docker Hub

      1
      2
      curl -s -H "Authorization: JWT ${TOKEN}" "https://hub.docker.com/v2/repositories/library/<image-name>/tags/?page_size=100" | jq -r '.results[] | select(.name == "<tag-name>") | .images[0].size' | numfmt --to=iec-i
      # "numfmt --to=iec-i" is for human readibility

      Example to get the compressed image size of alpine:latest

      1
      curl -s -H "Authorization: JWT ${TOKEN}" "https://hub.docker.com/v2/repositories/library/alpine/tags/?page_size=100" | jq -r '.results[] | select(.name == "latest") | .images[0].size' | numfmt --to=iec-i

    2. If the image is host on Microsoft Container Registry

      Parse method depends on the registry’s implementation and compability of docker HTTP Registry API.

      1
      docker manifest inspect -v devicedevex.azurecr.io/alpine-azure-sdk | grep size | awk -F ':' '{sum+=$NF} END {print sum}' | numfmt --to=iec-i

  2. Push your image to your domain in docker hub, you can see the compressed size listed on docker hub.

  3. Use docker save to save image to a .tar file and then compress it a .tar.gz file. 

    1
    2
    3
    4
    5
    6
    7
    docker save my-image:latest > my-image.tar

    # Compress the .tar file
    gzip my-image.tar

    # Check the size of the compressed image
    ls -lh my-image.tar.gz

  4. Using internet monitor to capture the data size transfered during docker pull might be inconcise due to HTTP’s network congestion control, etc. This method is not recommended.