1. Start from a Linux image

docker run -it ubuntu bash
or
docker run -it alpine sh
        

2. Copy the code to the running Linux container

docker cp
        

3. Install packages

pip install --no-cache-dir -r requirements.txt
        

4. Run and test the app in the container, may need to map port in step 1

5. Create a Dockerfile using the commonds conducted in step 1-4

# A Dockerfile must begin with a FROM instruction
# Specifies the Parent Image
FROM imageName

# Execute any commands in a new layer on top of the current image and commit the result
# Committed image will be used for the next step in the Dockerfile
RUN [command]

# Provide defaults for an executing container
# Only one CMD instruction in a Dockerfile
CMD [command]
CMD echo "Hello World" # (shell form)
CMD ["echo", "Hello World"] # (exec form)

# Add metadata to an image
LABEL [metadata]

# Expose the container port number when running the container
# It functions as a type of documentation between developers and users, exposed port number should match the port number of the app
EXPOSE [portNumber]

# Sets the environment variable
ENV MY_NAME="Lin"

# Copy new files, directories or remote file URLs from <src> and adds them to the filesystem of the image at the path <dest>
# Copy and auto-extract tar files
ADD [src] [dest]

# Copy local files and directories from src to dest
COPY [src][dest]

# Configure a container that will run as an executable
# Cannot add a command after the image
# docker run [imageName], legal
# docker run [imageName] sh, illegal, sh is taken as the parameter of ENTRYPOINT command
ENTRYPOINT [command]

# Set the user name for RUN, CMD and ENTRYPOINT instructions
USER [userName]

# Set the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD instructions
WORKDIR [dirName]

# Define the commands will be executed when the image is used as base
# Not affect the current image build
ONBUILD [DockerKey] [command]
		

Avoid unnecessarily sending large or sensitive files and directories to the daemon with ADD and COPY

# comment
*/temp*
*/*/temp*
temp?

*.md
!README.md # exception
        

docker build -t [imageName] .

# Check the size of each layer
docker history [iamgeName]
        

docker run [imageName]

# -e, create environment variables
docker run -e ENV_NAME=value [imageName]
        

Dockerfile reference