DOCKER

Docker in real life environment

Download and install docker from Docker

Verify the download using following command docker version should display in console

docker -v

Docker Image

It is a blueprint of container, like class and objects where Image acts as a class and containers are objects

Container

contains all the applications and resources that are needed for a project.

let's say we're using following modules

• mongodb v3
• node v19 and what not !

Let's say I am using node v19 and my teammate is using node v18. That's where docker kicks in and make the environment consistent, a dockerfile works as a package.json to setup the project environment

It eliminates "It works on my machine problem"

• They're portable
• They're light-weight
• They're isolated from local environment

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Docker Commands

To pull an image from hub.docker.com

docker pull IMAGE_NAME

Example:

docker pull hello-world

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To pull an image from hub.docker.com with version

docker pull IMAGE_NAME:version

Example:

docker pull mysql:8.0

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To list all the images

docker images

Execute an image

docker run IMAGE_NAME

Example

docker run hello-world

Example: Detached mode

docker run -d hello-world

Note: if you need to monitor the output of a container or interact with it, attached mode is more appropriate. The attached mode actively occupy the terminal.

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Run a image in interactive mode

docker run -it IMAGE_NAME

Example: This will start a ubuntu console

docker run -it ubuntu

NOTE: Docker run is used to create new containers out of the images Docker start is used to run existing containers with name or ID.

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Run a image assigning a name of container

docker run [-it] --name name IMAGE_NAME

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Exit/Stop the container in interactive mode

exit

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List all containers

docker ps -a

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List all containers that are running

docker ps

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Run existing containers

docker start ( CONTAINER_NAME || CONTAINER_ID )

Example: starting a container with name

docker start quirky_sanderson

Example: starting a container with ID

docker start 6cb01cd7814f (Initial 6-7 bits of long ID)

Example: starting a container in interative mode

docker start -i 6cb01cd7814f (Initial 6-7 bits of long ID)

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STOP running containers

docker stop ( CONTAINER_NAME || CONTAINER_ID )

Example: stopping a container with name

docker stop quirky_sanderson

Example: stopping a container with ID

docker stop 6cb01cd7814f (Initial 6-7 bits of long ID)

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Removing Images

Note: Containers with the image must be removed first

docker rm container_name

removing images

docker rmi image_name

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PORT BINDING

Note: PORT in containers differ from the host machine. To map the container ports with host machine we can use following commands

docker run -p HOST_PORT:CONTAINER_PORT IMAGE NAME

Example:

docker run -p5173:5174 reactENV

Setting ENV variable

docker run -e VAR_NAME=VAR_VALUE CONTAINER_NAME (or container_id)

Example:

docker run -e PORT=5000 reactENV

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Going to bin/bash of a container

Note: you have to start the container before creating the bash

docker exec -it CONTAINER bin/bash

Example:

docker run -e node:latest bin/bash

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Composing a docker image

Docker network is automatically made out of compose.yaml

docker compose -f compose.yaml up -d

docker compose -f compose.yaml down

Volumes - preserving data