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docker

Image of Docker Architecture

Table of Contents

Basic commands:

docker --version
docker info
docker hello-world
  • To run linux container and run bash in it: docker run -it ubuntu:latest bash (it stands for interactive terminal)

Containers

When we run an image we get a container.

  • To see running container: docker ps

  • To see running container with format:

	FORMAT=\nID\t{{.Id}}\nIMAGE\t{{Image}}
	echo $FORMAT
	docker ps --format $FORMAT

  • Check the last container: docker ps -l

  • Make docker images out of container, return image_id: docker commit container_id

  • To give image a name: docker tag image_id my-image

  • Short-hand to commit and give image a name: docker commit container_name my-image2

  • Test my-image by running process 'bash' in it docker run -it my-image bash

  • Run container for 5 sec docker run --rm -it ubuntu sleep 5

  • Run container with bash commands

	docker run -it ubuntu bash -c "sleep 3; echo all done"
	docker run --name my_container

  • Run and detach the container docker run -d -it ubuntu bash

  • attach the container docker attach container_name

  • detach container ctrl P ctrl Q

  • use same container parallely and start bash docker exec -ti container_name bash

  • To exit container ctrl D

  • Logs docker logs container_name

  • Killing and removing docker container docker kill container_name docker rm container_name

  • We can add memory constraints, CPU limits and various orchestrations to docker container

  • Building the container docker build -t container_build01

Images

  • Check present docker images:

     docker images
 docker rmi image_name

  • Running the image: docker run -d -p 80:80 \ --name docker_img01 container_build01

  • Pulling an image docker pull img_name:version_no

  • Pushing image to docker hub

     docker login
 docker tag docker_img01 akshaychaudhari/my-image01
 docker push akshaychaudhari/my-image01

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

  • Saving an image docker save -o my-images.tar.gz existing_image_name

  • Loading image docker image -i my-images.tar.gz

Exposing Ports

  • Setting and mapping ports of container and local machine:
    docker run --rm --it -p 45678:45678 -p 45679:45679 --name echo-server ubuntu:14.04 bash

  • Container's are not reliable to directly address other container's by IP Address. We can use 'host.docker.internal' instead localhost/ tnsname/ip address of the container.

  • If only intenal ports are given, docker assign external ports automatically. Those can be checked using:
    docker port container_name

  • This works with UDP Protocal as well as like TCP above.
    docker run outside_port:inside_port/protocol

  • UDP example using netcat:

    • at server:
      nc -ulp 45678
    • at client:
      docker port echo-server; nc -u localhost 327771;

Container Networking

	docker network ls
	docker create networt net_01

  • runing a container on specific network docker run --rm -it --net net_01 --name dogserver ubuntu:14.01 bash

  • containers in the same newtork can only commmunciate.

  • adding an exising container to a network. docker network connect net_02 catserver

Legacy Linking

  • One way linking of the port between 2 m/c. 
     docker run --rm -it -e SECRECT=jingalala --name catserver  ...
 docker run --rm -it --link catserver --name dogserver

Volumes

  • These are virtual disks for local disk host.
  1. Persistent
  • will persist on host if all containers are killed docker run -it -v 'C:\user\akshay':/shared-folder ubuntu bash
  1. Ephermal
  • will evaporate once no container is using it. 
     docker run -it -v /shared-folder ubuntu bash
 docker run -it --volume-from container_name_having_volume ubuntu bash

Registries

  • It manages and distributes images docker search ubuntu

Dockerfiles

  • Building images with code. docker build -t name-of-result_img docker-file-location

  • Not a shell scrpit, its just like it.

  • Process started on one line wont be running next line.

  • Each step is cached.

  • Each line is its own call to docker run

  • Env variable persist one multiline if we use ENV command.

  • Sample dockerfile 01:

FROM debian:sid
RUN apt-get -y update
RUN apt-get install nano
CMD ["/bin/nano" "/tmp/notes"]
`docker build -t example/new-img-02 .`
  • Sample dockerfile 02:
MAINTAINER akshay chaudhari <[email protected]>
FROM example/my-img-02
ADD notes.txt /notes.txt
ENV DB_HOST=db.prod.example.com
ENV DB_PORT=5432
CMD "nano" "/notes.txt"
`docker build -t example/new-img-02 .`

  • Avoid golden images creation. Always include all the dependecies.

  • Get the process id for given docker container docker inspect --format '{{.State.Pid}}' container_name

Docker Compose:

```
docker compose up
docker compose stop
```

Docker compose is basically used to work with multiple docker containers. For eg. a MEAN stack application could have 3 containers viz. client, server and database. So, to set it up in one go we can use docker compose command. This calls the docker-compose.YML file in the root directory and runs the respective containers as per docker-compose.YML file. Sample yml file:

version: "3.8"
services:
  webapp:
    build: ./dir

Read More at: https://docs.docker.com/compose/compose-file/

Orchestration Options:

  1. Kubernates
  2. Amazon EC2 Container Service (ECS)
  3. AWS fargate
  4. Docker sworm
  5. Google Kubernates Engine
  6. MS Azure Kubernates Service

Running a My-SQL Container:

docker run --name akshay-mysql2 -e MYSQL_ROOT_PASSWORD=root123 -d mysql -p 3306:3306

docker run --name akshay-mysql3 -e MYSQL_ROOT_PASSWORD=root123 -d mysql -h localhost -P 3306 --protocol=tcp

docker run -it --network first-network --rm mysql mysql -h akshay-mysql -u first-user -p

docker run -it --rm mysql mysql -hsome.mysql.host -usome-mysql-user -p

mysql -h localhost -P 3306 --protocol=tcp -u root

Running an angular app from a dockerfile:

  1. First write your dockerfile into root directory of your app (eg. /my-app/) Eg. dockerfile
	FROM node:6
	RUN mkdir -p /usr/src/app
	WORKDIR /usr/src/app
	COPY package.json /usr/src/app
	RUN npm cache clean
	RUN npm install
	COPY . /usr/src/app
	EXPOSE 4200
	CMD ["npm","start"]

  1. Invoke dockerfile using build to create an image for your project.
    docker build -t top-movie-app /app-root-path/

  2. Then run docker image on given port.
    docker run --rm -p 4200:4200 --name "TopMovies001" top-movie-app