Port Mapping/Binding

• Port Mapping / Port Binding is used to map the host port with the container port, to expose the container application to the internet.

• docker run -it -p <host_port>:<container_port>

  • e.g. docker run -it -p 8089:8080 tomcat

  • 

• Navigate to internet and access the container through public ip along with required port.

  • 

Docker Images

How to create Docker images and push to Container Registry

Docker Commit

• Create a container image based on the existing container reference

• docker commit <container_id> <Container_Repository_Name>/<New_Container_Image_Name>:<Tag>

Creation of Container image using Docker Commit:

• Let’s first login to any previous container

  • 

• Install some build tools like maven and git

  • 

• Exit the container and stop the container

  • 

• Let’s use this command : docker commit <container_id> <Container_Repository_Name>/<New_Container_Image_Name>:<Tag>

  • docker commit 7316260b08f0 jayk2810/build_tool_img:v2

  • 

• Now we can run the container using this image and check build tool are already installed

  • 

Push the Images to Container Registry

• Login to Container Registry using Docker CLI

  • Create Access Token in DockerHub

  • docker login -u <username>

    • Enter username and password

• Docker Push Command to Push the Image to Container Registry

  • docker push<Container_Repository_Name>/<New_Container_Image_Name>:<Tag>

  • 

• Check in Container registry that container image is pushed

  • 

Docker Build

• To create the new Container image on the Dockerfile reference

• Dockerfile composed of instructions to create docker container images.

• Application developer create the Dockerfile and update in the source code repository.

• Command : docker build -t <Container_Repository_Name>/<New_Container_Image_Name>:<Tag> . , “.” Denotes the Dockerfile Reference

  • First create the Dockerfile

    • 

    • 

    • “From” references base image

    • Now run the build command

    • 

  • 

Write Dockerfile :::

Docker File Instructions :::

• FROM - To Identify the Base Image

• RUN - To run the package manager

• COPY - To Copy the file from host volume to container volume

• CP - To Copy the file within the container volumes

• ADD - To Copy the file from Host Volume as well as from URL

• ENV - To define the Environment Variable

• ARG - To pass Arguements to the Steps in Dockerfile

• EXPOSE - To Define the Container Port

• WORKDIR - To set the current working directory within the Container

• CMD - To set the default start-up command to the container This Command can be changed at run-time.

• ENTRYPOINT - To set the default start-up command to the container This Command cannot be changed at run-time.

docker history <Image_Name>

• Used to find the Image Layers from Local Machine

  •