IM Demo

Project Architecture

.
├── .dockerignore        # files and folder to be ignored by COPY command
├── Dockerfile           # Dockerfile for building image
├── README.md            # README.md
├── app.py               # Application Code for Flask
└── requirements.txt     # Application Dependency

Docker Commands Explained

How to login to Docker Hub

docker login docker.io

How to pull a image from Docker Hub

docker pull image_name image_name is the name of image you want to pull

How to build docker image

Building with default Dockerfile

docker build . -t image_name

. is the context folder in our case current folder which contains the Dockerfile

Building with custom Dockerfile

docker build . -f Dockerfile.dev image_name

We assume we have a Dockerfile.dev in our context folder

How to run a image

Running without any run time config

docker run image_name if image_name is not present locally it will be pulled from container registry first, then will be run after downloading

How to map host port with container port in runtime

docker run -p 9000:8000 image_name

here the format -p host_port:container_port so any request to http://localhost:host_port will be redirected to container_port of the container. In our case http://localhost:9000 will be served by 5000 port of the container

How to pass environment variables in runtime

docker run -p 9000:8000 -e APP_NAME="Value" image_name

here we passed an environment variable APP_NAME with value Value. The format is -e name_of_env_variable=value_of_variable if the value_of_variable contains a space the encapsulate it in ""

How to push image

docker push image_name

How to see current containers

docker ps you will see a container list with container id

all the closed container or stopped container with be seen just appending -a flag

docker ps -a to see all the containers

How to see the images

docker images

How to see the files in a containers.

We can't see any file in any images. We have to run a container first with the image then go into the container console.

docker exec -it container_id /bin/bash

conatainer_id - conatiner id from docker ps /bin/bash - i want to start a bash session

by default the bash will be run in the WORKDIR of the container. in our case it's the /code folder.

How to optimize docker.

After using docker for sometimes, we will be having docker containers and images that we don't use. for that you can use docker system prune this will delete all the dangling images, containers, volumes and stuff.