basic docker syntax, source : https://www.youtube.com/watch?v=pg19Z8LL06w&t=16s

Docker_basic

# source : https://www.youtube.com/watch?v=pg19Z8LL06w&t=16s

# Docker images = Your Application include environment config , variables , directories
# Docker container = Actually starts the app

# One image can run multiple containers

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############################### COMMAND ################################
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#### LISTS ####

$ docker images 
# List all Docker images

$ docker ps
# Lists running container (Only running)

$ docker ps -a | --all
# Lists running container (Stopped and running)
# '|' means you can only use -a or --all

$ docker system prune -a
# for removing and cleaning up Docker images.

#### Start & Stop ####

$ docker start { CONTAINER_ID or name }
$ docker stop { CONTAINER_ID or name }

$ docker pull { name }:{ version(tags) }
# Pull an image from registry , Example : https://hub.docker.com/_/nginx/tags

$ docker run { name }:{ version(tags) }
# Creates a container from given image and starts it

$ docker run -d | --detach { name }:{ version(tags) }
# Runs container in background and Prints the container ID

$ docker run --name { name } -d { name }:{ version(tags) }
# Runs container in background and Prints the container ID with assigning it's name

$ docker run -p | --publish { HOST_PORT or any localhost }:{ CONTAINER_PORT } { name }:{ version(tags) }
# Publish container to the port

Example : docker run --name { name } -d -p { HOST_PORT }:{ CONTAINER_PORT } { name }:{ version(tags) }

#### LOGS ####

$ docker logs { CONTAINER_ID }
# View logs from service running inside the container. (Which are present at the time of execution)

#### More ####

https://docs.docker.com/reference/

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################################ CREATE Dockerfile ################################
#### we create docker file when we have our own app which is not 'pull' method ####
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FROM { name }:{ version(tags) }
# Build image from the specified image

RUN { command }
# Will execute any command in a shell inside the container environment

COPY { file or directory } { container path }
# Copies files or directories from <src> and adds them to the filesystem of the container at the path <dest>
# While 'RUN' is execute in the container, 'COPY' is execute on the host

Example : 
COPY myfile.json /app/
COPY <any diretories> /app/

WORKDIR { path }
# Sets the working directory for all following commands ( like $ cd <dir> )

CMD 
# The instruction that is to be executed when a Docker container starts
# There can only be one 'CMD' instruction in a Dockerfile

########### Dockerfile Example & how to correct syntax order ###########

FROM { name }:{ version(tags) }
COPY { file or directory } { container path }
WORKDIR { path }
RUN { command }
CMD [ "{ app name from 'FROM' }" , "{ file from 'COPY' }" ]

**Dockerfile is the definition to build Image**

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# To build Image
$ docker build -t | --tag { name }:{ tag } { location of Dockerfile }

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################################ VOLUME ################################
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a volume is a persistent storage location that exists outside of the container. 
Volumes are useful for storing data that needs to persist even if the container is stopped or removed. 
In a Dockerfile, the VOLUME instruction is used to specify a mount point for a volume within the container.

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############################# DOCKER-COMPOSE ###########################
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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.