Docker Basic with the most frequent docker commands!

First Lets go over some basic concepts of Docker.

What is a docker image?

• A docker image is mainly an application binary (a.k.a: setup file).
• An image might also consist of the dependencies of a specific application.
• An image does NOT consist of a Complete Operating System.
• An image does NOT consist of any KERNEL or KERNEL drivers.
  (As docker container shares the underline OS KERNEL)
• There is also a large Image available with OS, Driver & all.

What is Dockerfile?

• Docker images are created from Dockerfile.
• A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.
• Using docker build users can create an automated build that executes several command-line instructions in succession.

What is Docker Compose?

Compose is a tool for defining and running multi-container Docker applications.
With Compose, you use a YAML file to configure your application’s services. Then, with a single command, you create and start all the services from your configuration.

What is Docker Data Persistence?

By default data(ex: log files) doesn’t persist when that container no longer exists. But, Docker has two options for containers to store files in the host machine, so that the files are persisted even after the container stops.

we can persist data in Docker in two ways:
docker volumes, docker bind Mounts.

Docker Volumes

• It’s a configuration option for Creating Containers.
• It creates a special location outside of the container file system to store the data.
• we can attach this volume to one or many containers.
• If we remove a container having a docker volume, the data in the docker volume remains as it is.
• docker Volume needs manual Deletion.

Docker Bind Mounts

• It’s a process of mapping a host file or directory to a container file or directory.
• The container will treat the Bind mount file path like a local file path.
• we Can not use bind mounts in the docker file.
  we must create it with docker run or with docker-compose.

Docker Commands

Run a Nginx container in detached mode with the host network

docker container run --publish 80:80 --detach --name nginx_for_testing --net=host nginx

Run Mysql With default Password and Storage

docker container run --publish 3306:3306 --detach --name myssqlDB -e MYSQL_RANDOM_ROOT_PASSWORD=true mysql

Run Mysql With user given Password and Storage

docker container run -d -p 3306:3306 -e MYSQL_ROOT_PASSWORD=123321 -v /var/lib/docker/volumes/mysqldb:/var/lib/mysql --name mysqldb mysql

we are using docker bind mounts here.

This line
/var/lib/docker/volumes/mysqldb:/var/lib/mysql ,
is binding the
/var/lib/docker/volumes/mysqldb docker directory to the
/var/lib/mysql which is a server directory.

Get Container List

docker container ls
docker container ls -a

Start a specific Container

docker container start YOUR_GIVEN_CONTAINER_NAME

Get a log of a specific container

docker container logs YOUR_GIVEN_CONTAINER_NAME

Get a log of a specific container in realtime in the command line

docker container logs -f YOUR_GIVEN_CONTAINER_NAME

Get container Resource Usage

docker container top YOUR_GIVEN_CONTAINER_NAME

Check the extra information on a container

docker container inspect YOUR_GIVEN_CONTAINER_NAME

Stop a specific Container

docker container stop YOUR_GIVEN_CONTAINER_NAME

Get all the container status in realtime

docker container stats

Run docker in interactive Mode with Bash

docker container run -it YOUR_GIVEN_CONTAINER_NAME bash

Check if one container is accessible from another

docker container exec -it YOUR_GIVEN_CONTAINER_NAME ping YOUR_GIVEN_CONTAINER_NAME

Remove a specific Container

docker container rm -f YOUR_GIVEN_CONTAINER_NAME

Run container with a specific name & alias from a Image

docker container run -d --net NETWORK_NAME --net-alias NETWORK_ALIAS_NAME IMAGE_NAME

Check all the DNS entries of a specific NETWORK_ALIAS_NAME

docker container run --rm --net NETWORK_NAME alpine nslookup NETWORK_NAME

Get the list of all image

docker images ls

Show the history of an image

docker image history IMAGE_NAME:IMAGE_TAG

Inspect a docker Image

docker image inspect IMAGE_NAME

Tag an image

docker image tag SOURCE_IMAGE_NAME TARGET_IMAGE_NAME

Build an image with Custom Name in the current directory

docker image build -t YOUR_GIVEN_CUSTOM_NAME

Remove Docker Image

docker rmi IMAGE-NAME

Inspect the default Bridge Interface

docker network inspect bridge

Create a New Network

docker network create YOUR_GIVEN_NETWORK_NAME

Add a network to the container

docker network connect YOUR_GIVEN_NETWORK_NAME YOUR_GIVEN_CONTAINER_NAME

Remove a network from a container

docker network disconnect YOUR_GIVEN_NETWORK_NAME YOUR_GIVEN_CONTAINER_NAME

Build Image from a docker file

docker build -f PATH_TO_DOCKERFILE

See the Space used by the docker container & images

docker system df

Get all the created docker volume

docker volume ls

Create a new docker volume

docker volume create YOUR_GIVEN_VOLUME_NAME

inspect a docker volume

docker volume inspect YOUR_GIVEN_VOLUME_NAME

Among many others, these are the few most frequently used docker commands.

You can check the docker official Site or the docker cheat sheet for more in-depth information.

Thanks for reading and you can let me know if you have any questions or suggestions.

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