Introduction

In this tutorial, We will delve into the fundamental Docker commands crucial for anyone working with this widely adopted containerization tool. Docker has become a cornerstone for developers and DevOps engineers, providing a streamlined approach to constructing, transporting, and executing applications within containers.

Its simplicity and efficiency make it an indispensable asset in application deployment and management. Whether you are a novice exploring Docker’s capabilities or a seasoned professional implementing it in production, understanding these essential commands is pivotal.

This article aims to highlight and explain the ten imperative Docker commands that will be integral to your routine tasks.

10 Docker Commands

Docker run

The docker run the command is used to start a new container from an image. It is the most basic and commonly used Docker command. Here’s an example of how to use it:

docker run nginx

This command will download the latest Nginx image from the Docker Hub and start a new container from it. The container will be started in the foreground and you can see the logs as they are generated.

docker ps

The docker ps the command is used to list the running containers on your system. It provides information such as the container ID, image name, and status. Here’s an example of how to use it:

docker ps

This command will display a list of all the running containers on your system. If you want to see all containers (including stopped containers), you can use the -a option:

docker ps -a

This will display a list of all the containers on your system, regardless of their status.

docker stop

The docker stop the command is used to stop a running container. It sends a SIGTERM signal to the container, allowing it to gracefully shut down. Here’s an example of how to use it:

docker stop mycontainer

This command will stop the container with the name mycontainer. If you want to forcefully stop a container, you can use the docker kill command:

docker kill mycontainer

This will send a SIGKILL signal to the container, which will immediately stop it. However, this may cause data loss or other issues if the container is not properly shut down.

docker rm

The docker rm command is used to remove a stopped container.

syntax

docker rm <container>

For example, to remove the container with the ID “xxx123“, you can use the command

docker rm xxx123

docker images

The docker images command is used to list the images available locally. This command will display a list of all the images that are currently available on your system.

docker rmi

The docker rmi the command is used to remove a local image.

syntax

docker rmi <image>

For example, to remove the image with the name “myimage“, you can use the command.

docker rmi myimage

docker logs

The docker logs command is used to show the logs of a running container.

Syntax

docker logs <container>

For example, to show the logs of the container with the ID “xxx123“, you can use the command docker logs xxx123.

docker exec -it

The docker exec command is used to run a command inside a running container.

syntax

docker exec -it <container> <command>

For example, to run a bash shell inside the container with the ID “xxx123“, you can use the command

docker exec -it xxx123 bash

docker build -t

The docker build command is used to build a Docker image from a Dockerfile file.

syntax

docker build -t <image> <path>

For example, to build an image with the name “myimage” From a Dockerfile located in the current directory, you can use the command

docker build -t myimage .

docker-compose up

The docker-compose command is used to start containers defined in a docker-compose file. This command will start all the containers defined in the Compose file.

Conclusion

These are the top Docker commands that you’ll use frequently when working with Docker. Mastering these commands will help you get started with Docker and make it easier to deploy and manage your applications. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial, How to run Python on Docker. Python is a programming language. Python Docker image is the latest point release. 

The Docker image version was released in March 2022.

You need to install Docker on Ubuntu.

The working directory python docker:

root@devopsroles:~/dockerpython# ls -lF
total 20
-rw-r--r-- 1 root root  111 Nov 20 14:31 app.py
-rw-r--r-- 1 root root  236 Nov 20 15:00 Dockerfile
-rw-r--r-- 1 root root   20 Nov 20 14:27 requirements.txt

How to build a Docker container running a simple Python application.

Setup dockerfile python

Create a folder and create a virtual environment. This isolated the environment for the Python Docker project.

For example

mkdir dockerpython
cd dockerpython
python3 -m venv dockerpython
source dockerpython/bin/activate

Create a new file dockerfile python.

FROM python:3.9-slim-buster
ENV PYTHONUNBUFFERED=1
WORKDIR /app

COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt

COPY . .
EXPOSE 5000

CMD [ "python3", "-m" , "flask", "run", "--host=0.0.0.0", "--port=5000"]

Save and close.

Create the Python App

Create an app.py file. For example as below

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
     return 'Hello, Docker!'

Save and close.

Create the requirements.txt file. This contains dependencies for the app to run.

For example, we add the packages for the requirements.txt file.

Flask=2.0.3
pylint

Or method 2: show all packages installed via pip use pip3 freeze and save to the requirements.txt file.

pip3 install Flask
pip3 freeze | grep Flask >> requirements.txt

we will test if the works localhost using the command below

python3 -m flask run --host=0.0.0.0 --port=5000

Open the browser with the URL http://localhost:5000

Docker Build image and container

You build a Docker image from created Dockerfile. Use the command below to build the Docker image

docker build --tag dockerpython .

Tag the image using the syntax

docker tag <imageId> <hostname>/<imagename>:<tag>

For example, Tag the image.

docker tag 8fbb6cdc5e76 huupv/dockerpython:latest

Now, the Run Docker image has the created and tagged with the command line below:

docker run --publish 5000:5000 <imagename>

Use the command below to list containers running.

docker ps

The result below:

You can now test your application using http://localhost:5000 on your browser.

Docker pushed and retrieved from Docker Hub

The container will be pushed and retrieved from the Docker Hub registry. The command simple

docker push <hub-user>/<repo-name>:<tag>.

On the website Docker Hub. Click Create Repository to give the repo a name.

Create 1 repo name and description as below:

Copy the command to your terminal, replacing tagname with version latest.

In your terminal, we run the command docker login to connect the remote repository to the local environment. Add username and password to valid login.

Run the command to push to the repository you created it.

docker push <hub-user>/<repo-name>:tagname

Confirm your image to be pushed to the Docker Hub page

In any terminal, Docker pulls the Docker image from Docker Hub.

root@devopsroles:~# docker pull huupv/dockerpython:latest

For example, use Docker Compose

version: "3.9"  
services:
  web:
    build: .
    ports:
      - "5000:5000"
    volumes:
      - .:/app
      - logvol:/var/log
    links:
      - redis
  
 redis:
     image: redis
 volumes:
   logvol: {}

Conclusion

You know How to run Python on Docker. I hope this will be helpful. Thank you for reading the DevopsRoles page!

#Introduction

In this tutorial, How to Install MariaDB via docker. MariaDB is a popular open-source database server.

You need to install Docker on Ubuntu.

Install MariaDB via Docker

Download MariaDB Docker Image.

docker search mariadb
docker pull mariadb

Get a list of installed images on Docker.

docker images

Creating a MariaDB Container

We will create a MariaDB Container such as the flags below:

• –name my-mariadb: To set the name of the container. If nothing is specified a random if will be automatically generated.
• –env MYSQL_ROOT_PASSWORD=password_secret: Setting root password to Mariadb.
• –detach is to run the container in the background.

docker run --detach --name my-mariadb --env MARIADB_USER=example-user --env MARIADB_PASSWORD=example_user_password_secret --env MARIADB_ROOT_PASSWORD=password_secret mariadb:latest

Get the active docker container

docker ps

The container is running, How to access it?

docker exec -it my-mariadb mysql -uexample-user -p

Starting and Stopping MariaDB Container

restart MariaDB container

docker restart my-mariadb

stop MariaDB container

docker stop my-mariadb

start MariaDB container

docker start my-mariadb

In case we want to destroy a container,

docker rm -v my-mariadb

Conclusion

You Install MariaDB via Docker container. I hope this will be helpful. Thank you for reading the DevopsRoles page!

Introduction

In this tutorial, How to Deploy MongoDB as a Docker container. MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas.

In today’s world of modern application development, containerization has become a popular approach for deploying and managing applications.

Install Docker

You need to install Docker on Ubuntu.

How to Deploy MongoDB as a Docker Container

First, We will pull version MongoDB as command below:

docker pull mongo:3.4.4

To create a volume for the database and retain data. The command line creates the volume as below:

docker volume create mongo_data

We will deploy it

docker run -d -v mongo_data:/data/db --name mymongoDB --net=host mongo:3.4.4 --bind_ip 127.0.0.1 --port 27000

You need to verify the deployment as command below:

docker ps -a

The container is running, How to access it?

docker exec -it mymongoDB mongo localhost:27000

If you need to stop the MongoDB container.

docker stop ID

If you need to start the MongoDB container.

docker start ID

Conclusion

You have successfully deployed MongoDB as a Docker container. This approach offers flexibility, scalability, and portability for your MongoDB deployments. With containerization, you can easily manage your database infrastructure and ensure consistency across different environments. I hope this will be helpful. Thank you for reading the DevopsRoles page!