Day 18 Task: Docker for DevOps Engineers

#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.

#What is YAML?

i). YAML stands for yet another markup language

ii). YAML is a human-readable data serialization language that is often used for writing configuration files

iii). YAML is a popular programming language because it is designed to be easy to read and understand.

iv). It can also be used in conjunction with other programming languages. Because of its flexibility and accessibility, YAML is used by the Ansible automation tool to create automation processes

v). YAML files use a .yml or .yaml extension and follow specific syntax rules.

vi). A common question for YAML beginners is “What do the 3 dashes mean?” 3 dashes (---) are used to signal the start of a document, while each document ends with three dots (...).

#task

1. Learn how to use the docker-compose.yml file, to set up the environment,

configure the services and links between different containers,

and also to use environment variables in the docker-compose.yml file.

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1)Install docker-compose

2)Create a docker-compose.yml file inside the project folder

-version: "3.3" denotes that we are using version 3.3 of Docker Compose.

-The services section defines all the different containers we will create.

-The build keyword specifies the location of our Dockerfile, and . represents the directory where the docker-compose.yml file is located.

-The image keyword is used to specify the image from the docker hub for MySQL containers

-For the database and web, we are using the ports keyword to mention the ports that need to be exposed.

And then, we also specify the environment variables for MySQL which are required to run MySQL.

i). vim docker-compose.yml

ii). cat docker-compose.yml

3)Run the docker-compose.yml file

3)Run docker-compose.yml file

iii). docker-compose up -d

iv). docker-compose down

Task-2

1). -Pull a pre-existing Docker image from a public repository (e.g. Docker Hub) and run it on your local machine. Run the container as a non-root user (Hint- Use usermod command to give the user permission to docker). Make sure you reboot the instance after permitting the user.

2). Inspect the container's running processes and exposed ports using the docker inspect command.

3). Use the docker logs command to view the container's log output.

4). Use the docker stop and docker start commands to stop and start the container.

5). Use the docker rm command to remove the container when you're done.