image2df is a tool for Generate Dockerfile by an image.

This tool is very useful when you only have docker image and need to generate a Dockerfile with it.

It is not applicable to multi-stage builds where a COPY --from= statement, because the image history data of multi-stage build information has been lost.

The "FROM <basc_image>" maybe is not accurate.

If you want to get an accurate basc_image info, you should build a Library for mapping images tag with files sha256 value, a file sha256 value like ADD file:f278386b0cef68136129f5f58c52445590a417b624d62bca158d4dc926c340df in / .

# Command alias
echo "alias image2df='docker run --rm --privileged -v /var/run/docker.sock:/var/run/docker.sock cucker/image2df'" >> ~/.bashrc
. ~/.bashrc

# Excute command
image2df <IMAGE>

• See help

  docker run --rm cucker/image2df --help

• For example

  $ echo "alias image2df='docker run --rm --privileged -v /var/run/docker.sock:/var/run/docker.sock cucker/image2df'" >> ~/.bashrc
  $ . ~/.bashrc
  $ docker pull mysql
  $ image2df mysql
  
  # ========== Dockerfile ==========
  FROM mysql:latest
  RUN groupadd -r mysql && useradd -r -g mysql mysql
  RUN apt-get update && apt-get install -y --no-install-recommends gnupg dirmngr && rm -rf /var/lib/apt/lists/*
  ENV GOSU_VERSION=1.12
  RUN set -eux; \
      savedAptMark="$(apt-mark showmanual)"; \
      apt-get update; \
      apt-get install -y --no-install-recommends ca-certificates wget; \
      rm -rf /var/lib/apt/lists/*; \
      dpkgArch="$(dpkg --print-architecture | awk -F- '{ print $NF }')"; \
      wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch"; \
      wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch.asc"; \
      export GNUPGHOME="$(mktemp -d)"; \
      gpg --batch --keyserver hkps:https://keys.openpgp.org --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4; \
      gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu; \
      gpgconf --kill all; \
      rm -rf "$GNUPGHOME" /usr/local/bin/gosu.asc; \
      apt-mark auto '.*' > /dev/null; \
      [ -z "$savedAptMark" ] || apt-mark manual $savedAptMark > /dev/null; \
      apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
      chmod +x /usr/local/bin/gosu; \
      gosu --version; \
      gosu nobody true
  RUN mkdir /docker-entrypoint-initdb.d
  RUN apt-get update && apt-get install -y --no-install-recommends \
          pwgen \
          openssl \
          perl \
          xz-utils \
      && rm -rf /var/lib/apt/lists/*
  RUN set -ex; \
      key='A4A9406876FCBD3C456770C88C718D3B5072E1F5'; \
      export GNUPGHOME="$(mktemp -d)"; \
      gpg --batch --keyserver ha.pool.sks-keyservers.net --recv-keys "$key"; \
      gpg --batch --export "$key" > /etc/apt/trusted.gpg.d/mysql.gpg; \
      gpgconf --kill all; \
      rm -rf "$GNUPGHOME"; \
      apt-key list > /dev/null
  ENV MYSQL_MAJOR=8.0
  ENV MYSQL_VERSION=8.0.24-1debian10
  RUN echo 'deb https://repo.mysql.com/apt/debian/ buster mysql-8.0' > /etc/apt/sources.list.d/mysql.list
  RUN { \
          echo mysql-community-server mysql-community-server/data-dir select ''; \
      echo mysql-community-server mysql-community-server/root-pass password ''; \
      echo mysql-community-server mysql-community-server/re-root-pass password ''; \
      echo mysql-community-server mysql-community-server/remove-test-db select false; \
      } | debconf-set-selections \
      && apt-get update \
      && apt-get install -y \
          mysql-community-client="${MYSQL_VERSION}" \
          mysql-community-server-core="${MYSQL_VERSION}" \
      && rm -rf /var/lib/apt/lists/* \
      && rm -rf /var/lib/mysql && mkdir -p /var/lib/mysql /var/run/mysqld \
      && chown -R mysql:mysql /var/lib/mysql /var/run/mysqld \
      && chmod 1777 /var/run/mysqld /var/lib/mysql
  VOLUME [/var/lib/mysql]
  COPY dir:2e040acc386ebd23b8571951a51e6cb93647df091bc26159b8c757ef82b3fcda in /etc/mysql/
  COPY file:345a22fe55d3e6783a17075612415413487e7dba27fbf1000a67c7870364b739 in /usr/local/bin/
  RUN ln -s usr/local/bin/docker-entrypoint.sh /entrypoint.sh # backwards compat
  ENTRYPOINT ["docker-entrypoint.sh"]
  EXPOSE 3306 33060
  CMD ["mysqld"]

1. Get the image history data by Docker API of python SDK, the data format is a List (python).

   >>> import docker
   >>> client = docker.DockerClient(base_url='unix:https://var/run/docker.sock')
   >>> hist = client.images.get("image_name_or_id").history()
   >>> print(hist)
   >>> 
   >>> # for mysql 
   >>> hist = client.images.get("mysql").history()
   >>> print(hist)
   >>> [
       {
           'Comment': '',
           'Created': 1618858607,
           'CreatedBy': '/bin/sh-c#(nop)CMD[
               "mysqld"
           ]',
           'Id': 'sha256: 0627ec6901db4b2aed6ca7ab35e43e19838ba079fffe8fe1be66b6feaad694de',
           'Size': 0,
           'Tags': [
               'mysql: latest'
           ]
       },
       ...
   ]
   

2. Parse the history data by a python script--generate_dockerfile.py.

• Prerequisites

  • Install Docker Engine
  • Python 3
  • Docker SDK for Python

• Prepare files

  /mydocker/image2df/
  ├── Dockerfile
  ├── generate_dockerfile.py  // generate dockerfile script of python
  └── requirements.txt  // requirements for python module
  

  • Dockerfile
  • generate_dockerfile.py
  • requirements.txt

• Create repository

  login to https://hub.docker.com, Create a repository, format is <ID>/repository-name, for example: cucker/image2df

• Build image

  cd /mydocker/image2df/
  docker build -f ./Dockerfile -t cucker/image2df:1.0 .

• Tag image alias

  docker tag cucker/image2df:1.0 cucker/image2df:latest

• Push image to DockerHub

  • login in DockerHub

    $ docker login  
    Username:    // user_ID
    Password:    // password

  • push image

    docker push cucker/image2df:1.0
    docker push cucker/image2df:latest

• Prerequisites
  • Install Docker Engine
  • Python 3
  • Docker SDK for Python

    pip install docker six

• Copy generate_dockerfile.py script to workdir
• Usage

  python ./generate_dockerfile.py <IMAGE>

• Example whit docker API for http

  reference

  • https://docker-py.readthedocs.io/en/stable/
  • https://docker-py.readthedocs.io/en/stable/client.html#client-reference
  • https://docs.docker.com/engine/api/sdk/examples/
  • https://docs.docker.com/engine/api/v1.41/#operation/ImageHistory
  • https://docs.docker.com/engine/api/sdk/
  • Docker API version with Docker version matrix