This post is just a simple note.

More detail in this video: https://www.youtube.com/watch?v=3c-iBn73dDE

Difference Image and Container

  • CONTAINER is a running environment for IMAGE
    • virtual file system
    • port blinded: talk to application running inside of container
    • application image: postgres, redis, mongo, …
  • redis in dockerhub are images
docker pull postgres
docker pull redis

# lists installed images
docker images

docker run redis
# `-d` means running in detached mode
docker run -d redis

# lists running container
docker ps
# lists running and stopped container
docker ps -a

# stops the container
docker stop <CONTAINER ID>
# start the container
docker start <CONTAINER ID>

# pulls image and starts container
docker run redis:4.0

CONTAINER Ports vs HOST ports

  • Multiple containers can run on your host machine
  • Your laptop has only certain ports available
  • Conflict when same port on host machine
host docker
Port 5000 Port 5000
Port 3000 Port 3000
Port 3001 Port 3000 
docker run -p6000:6379 redis

docker logs <CONTAINER ID>

docker logs <CONTAINER NAMES>

docker run -d -p6000:6379 --name redis-older redis:4.0

# it Interactive Terminal
docker exec -it <CONTAINER ID> /bin/bash
docker exec -it <CONTAINER NAMES> /bin/bash
# if no bash installed
docker exec -it <CONTAINER ID> /bin/sh
docker exec -it <CONTAINER NAMES> /bin/sh

# create a new container from a image
docker run
# start a exist container
docker start

docker pull mongo
docker pull mongo-express

docker network ls

docker network create <NETWORK NAME>

docker run -d \
    -p 27017:27017 \
    -e MONGO_INITDB_ROOT_USERNAME=admin \
    -e MONGO_INITDB_ROOT_PASSWORD=password \
    --network mongo-network \
    --name mongodb \
    mongo

docker run -d \
    -p 8081:8081 \
    -e ME_CONFIG_MONGODB_ADMINUSERNAME=admin \
    -e ME_CONFIG_MONGODB_ADMINPASSWORD=password \
    -e ME_CONFIG_MONGODB_PORT=27017 \
    -e ME_CONFIG_MONGODB_SERVER=mongodb \
    --net mongo-network \
    --name mongo-express \
    mongo-express

docker logs <CONTAINER ID> -f
docker logs <CONTAINER ID> | tail
docker logs <CONTAINER ID> | more

Docker Compose

docker run command

docker run -d \
    -p 27017:27017 \
    -e MONGO_INITDB_ROOT_USERNAME=admin \
    -e MONGO_INITDB_ROOT_PASSWORD=password \
    --network mongo-network \
    --name mongodb \
    mongo

docker run -d \
    -p 8081:8081 \
    -e ME_CONFIG_MONGODB_ADMINUSERNAME=admin \
    -e ME_CONFIG_MONGODB_ADMINPASSWORD=password \
    -e ME_CONFIG_MONGODB_PORT=27017 \
    -e ME_CONFIG_MONGODB_SERVER=mongodb \
    --net mongo-network \
    --name mongo-express \
    mongo-express

mongo-docker-compose.yaml

version: '3'
services:
  mongodb:
    image: mongo
    ports:
      - 27017:27017
    environment:
      - MONGO_INITDB_ROOT_USERNAME=admin
      - MONGO_INITDB_ROOT_PASSWORD=password
  mongo-express:
    image: mongo-express
    ports:
      - 8081:8081
    environment:
      - ME_CONFIG_MONGODB_ADMINUSERNAME=admin
      - ME_CONFIG_MONGODB_ADMINPASSWORD=password
      - ME_CONFIG_MONGODB_PORT=27017
      - ME_CONFIG_MONGODB_SERVER=mongodb

Docker Compose takes care of creating a common Network!

docker-compose -f mongo-docker-compose.yaml up
docker-compose -f mongo-docker-compose.yaml up -d
docker-compose -f mongo-docker-compose.yaml down

Dockerfile

  • Blueprint for building images

Image Environment Blueprint

install node

set MONGO_DB_USERNAME = admin
set MONGO_DB_PASSWORD = password

create /home/app folder

copy current folder files to /home/app

start the app with: "node server.js"

DOCKERFILE

FROM node

ENV MONGO_DB_USERNAME=admin \
    MONGO_DB_PASSWORD=password

RUN mkdir -p /home/app

COPY ./app /home/app

CMD [ "node", "/home/app/server.js" ]
  • FROM: Start by basing it on another image
  • ENV: Optionally define environment variables
  • RUN: execute any Linux command
  • COPY: executes on the HOST machine
  • CMD: entry point command

The name must be “Dockerfile”

docker build -t my-app:1.0 .

# DELETE A IMAGE
docker rmi <IMAGE ID>

# DELETE A CONTAINER
docker rm <CONTAINER ID>

docker pull mongo:4.2
docler pull docker.io/library/mongo:4.2

docker tag my-app:1.0 327587328957.dkr.ecr.eu-central-1.amazonaws.com/my-app:1.0

docker push 327587328957.dkr.ecr.eu-central-1.amazonaws.com/my-app:1.0

Docker Volumes

Container use virtual file system. When you stop or restart the container, all the data is GONE!

Folder in physical host file system is mounted into the virtual file system of Docker.

Host Volumes

docker run \
    -v /home/mount/data:/var/lib/mysql/data

You decide where on the host file system the reference is made.

Anonymous Volumes

docker run \
    -v /var/lib/mysql/data

for each container a foldre is generated that gets mounted.

Automatically created by Docker

Named Volumes

docker run \
    -v name:/var/lib/mysql/data

you can reference the volume by name

should be used in production

Docker Volumes in docker-compose

version: '3'
services:
  mongodb:
    image: mongo
      ports:
        - 27017:27017
      volumes:
        - db-data:/var/lib/mysql/data
  mongo-express:
    ...
volumes:
  db-data:
    driver: local

version: '3'
services:
  mongodb:
    image: mongo
    ports:
      - 27017:27017
    environment:
      - MONGO_INITDB_ROOT_USERNAME=admin
      - MONGO_INITDB_ROOT_PASSWORD=password
    volumes:
      - mongo-data:/data/db
      - mysql-data:/var/lib/mysql
      - postgres-data:/var/lib/postgresql/data
  mongo-express:
    image: mongo-express
    ports:
      - 8080:8081
    environment:
      - ME_CONFIG_MONGODB_ADMINUSERNAME=admin
      - ME_CONFIG_MONGODB_ADMINPASSWORD=password
      - ME_CONFIG_MONGODB_PORT=27017
      - ME_CONFIG_MONGODB_SERVER=mongodb
volumes:
  mongo-data:
    driver: local
  mysql-data:
    driver: local
  postgres-data:
    driver: local

Docker Volume Locations

  • Windows: C:\ProgramData\docker\volumes
  • Linux: /var/lib/docker/volumes
  • OS X: /var/lib/docker/volumes

Docker for Mac creates a Linux virtual machine and stores all the Docker data here.