Hello Everyone!

Let's explore another concept of Docker which is Docker Compose.

• Docker Compose is a tool that was developed to help define and share multi-container applications.

• With Compose, we can create a YAML file to define the services and with a single command, can spin everything up or tear it all down.

• It can start all containers with a single command i.e. docker compose up

• It can stop all containers with a single command i.e. docker compose down

What is YAML?

• YAML is a data serialization language that is often used for writing configuration files. Depending on whom you ask, YAML stands for yet another markup language or YAML ain’t markup language (a recursive acronym), which emphasizes that YAML is for data, not documents.

• YAML is a popular programming language because it is human-readable and easy to understand.

• YAML files use a .yml or .yaml extension.

Docker-compose

Install docker-compose:

• I'm using an AWS instance with Amazon Linux 2 OS. These are the commands by which I installed on my server.

    sudo curl -L https://github.com/docker/compose/releases/latest/download/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose
  
    sudo chmod +x /usr/local/bin/docker-compose
  
    docker-compose version
  

Create a Docker compose file:

• touch docker-compose.yml

version: '3'
services:
  db:
     image: mysql
     container_name: mysql_db
     restart: always
     environment:
        - MYSQL_ROOT_PASSWORD="secret"
  web:
    image: apache
    build: .
    container_name: apache_web
    restart: always
    ports:
      - "8080:80"

• Check the docker-compose file by using docker-compose config

Execute the file:

• docker-compose up

• Check for the containers after the above command.

• Similarly, we can stop all containers by using docker-compose down

The difference between a Docker file and Docker compose

Dockerfile

A Dockerfile is a simple text file that contains the commands a user could call to assemble an image.

Example,

Dockerfile:

FROM ubuntu:latest
MAINTAINER john doe 

RUN apt-get update
RUN apt-get install -y python python-pip wget
RUN pip install Flask

ADD hello.py /home/hello.py

WORKDIR /home

Docker Compose

Docker Compose

• is a tool for defining and running multi-container Docker applications.

• define the services that make up your app in docker-compose.yml so they can be run together in an isolated environment.

• get an app running in one command by just running docker-compose up

Example, docker-compose.yml

Dockerfile

A Dockerfile is a simple text file that contains the commands a user could call to assemble an image.

Example, Dockerfile

FROM ubuntu:latest
MAINTAINER john doe 

RUN apt-get update
RUN apt-get install -y python python-pip wget
RUN pip install Flask

ADD hello.py /home/hello.py

WORKDIR /home

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Docker Compose

Docker Compose

• is a tool for defining and running multi-container Docker applications.

• define the services that make up your app in docker-compose.yml so they can be run together in an isolated environment.

• get an app running in one command by just running docker-compose up

Example

docker-compose.yml:

version: "3"
services:
  web:
    build: .
    ports:
    - '5000:5000'
    volumes:
    - .:/code
    - logvolume01:/var/log
    links:
    - redis
  redis:
    image: redis
    volumes:
      logvolume01: {}

difference between dockerfile and docker-compose.yml

References:

Docker compose

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Thanks for reading ;)