A container is launched by running an image.

An image is an executable package that includes everything needed to run an application – the code, a runtime, libraries, environment variables, and configuration files.

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## Display Docker version and info
docker version
docker info

Dockerfile

Dockerfile defines what goes on in the environment inside your container.

Docker can build images automatically by reading the instructions from a Dockerfile.

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FROM python:3.7.4-alpine3.10
WORKDIR /app
COPY . /app
RUN pip install ipython
RUN pip install --trusted-host pypi.python.org -r requirements.txt
CMD ["ipython"]

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docker build app .

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# Copy file from local machine to docker
docker run -it -v `pwd`:/files alpine

The docker build command builds an image from a Dockerfile and a context.

Note that each instruction is run independently, and causes a new image to be created - so RUN cd /tmp will not have any effect on the next instructions.

The instruction is not case-sensitive. However, convention is for them to be UPPERCASE to distinguish them from arguments more easily.

A Dockerfile must start with a FROM instruction.
The FROM instruction specifies the Base Image from which you are building.

Difference between Docker Create, Start and Run

Create adds a writeable container on top of your image and sets it up for running whatever command you specified in your CMD. The container ID is reported back but it’s not started.

Start will start any stopped containers. This includes freshly created containers.

Run is a combination of create and start. It creates the container and starts it.

CLI

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docker run
docker ps
docker images
docker start
docker stop
docker exec

Register

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docker run -d -p 5000:5000 --restart=always --name registry registry:2

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docker pull ubuntu:16.04
docker tag ubuntu:16.04 localhost:5000/my-ubuntu
docker push localhost:5000/my-ubuntu

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docker image remove ubuntu:16.04
docker image remove localhost:5000/my-ubuntu

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docker pull localhost:5000/my-ubuntu

HTTP

/etc/docker/daemon.json

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{
  "insecure-registries" : ["http://myregistrydomain.com:5000"]
}

Docker CLI will try using HTTPS first!

https://docs.docker.com/registry/insecure/

Tips

Run without exiting

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docker run -dit ubuntu