Basic Docker Commands

docker.txt

Docker: Images and Containers: Runtime instance of an image Kitematic

Containers and VMs: On Linux, containers run natively and shares the same kernel as OS. Runs a discrete process and is lightweight. VM runs a separate guest OS with access to resources through a hypervisor. 

Containerization because:
1.	Flexible: Most complex apps
2.	Interchangeable: Deployment on the fly
3.	Portable: Build locally, deploy and run anywhere 
4.	No installation needed except docker
5.	Lightweight, makes CI/CD seamless. Dependency management becomes seamless.
Basic Docker commands
1.	$ docker pull busybox
2.	docker image ls -a                             # List all images on this machine
3.	docker container ls                                # List all running containers
4.	docker run -p 4000:80 friendlyhello  # Run "friendlyname" mapping port 4000 to 80
5.	$ docker ps
6.	docker container ls -a             # List all containers, even those not running
7.	docker container stop <hash>           # Gracefully stop the specified container
8.	docker container kill <hash>         # Force shutdown of the specified container
9.	docker container rm <hash>        # Remove specified container from this machine
10.	docker container rm $(docker container ls -a -q)         # Remove all containers
11.	$ docker container prune
12.	$ docker image rm <image id>            # Remove specified image from this machine
13.	docker image rm $(docker image ls -a -q)   # Remove all images from this machine
14.	docker login             # Log in this CLI session using your Docker credentials
15.	$ docker stop
16.	docker tag <image> username/repository:tag  # Tag <image> for upload to registry
17.	docker push username/repository:tag            # Upload tagged image to registry
18.	docker run username/repository:tag                   # Run image from a registry
19.	docker build -t friendlyhello .  # Create image using this directory's Dockerfile

Sample Dockerfile
# Use an official Python runtime as a parent image
FROM python:2.7-slim
# Set the working directory to /app
WORKDIR /app
# Copy the current directory contents into the container at /app
ADD . /app
# Install any needed packages specified in requirements.txt
RUN pip install --trusted-host pypi.python.org -r requirements.txt
# Make port 80 available to the world outside this container
EXPOSE 80
# Define environment variable
ENV NAME World
# Run app.py when the container launches
CMD ["python", "app.py"]