Docker Quickstart: Install, Build & Deploy Apps
Docker has become the backbone of modern DevOps and software delivery. It helps you build, ship, and run applications quickly and reliably. In this post, we’ll explore Docker installation, pulling and building images, running containers, using volumes, networks, Docker Compose, and finally scanning your images for security.
And yes — you’ll see real commands you can copy-paste!
Step 1: Install Docker on Ubuntu
Let’s get Docker up and running:
sudo apt update && sudo apt upgrade -y
sudo apt install docker.io -yNext, add your user to the Docker group to avoid typing sudo every time and Confirm it works:
sudo usermod -aG docker $USER
newgrp docker
docker --version
docker psStep 2: Pull & Run a Docker Image
Docker Hub is a library of prebuilt images. For example, let’s run MySQL 5.7:
docker pull mysql:5.7
docker imagesRun a container:
docker run -d -e MYSQL_ROOT_PASSWORD=my-secret-pw mysql:5.7Enter the container:
docker exec -it <container-id> bashInside, log into MySQL and create a database (replace tushar with your name):
mysql -u root -p
CREATE DATABASE tushar;Step 3: Build & Push Your Own Docker Image
Let’s create and publish a simple Java “Hello World” container.
Create Hello.java:
public class Hello {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}Then, create Dockerfile:
FROM openjdk:8
COPY Hello.java .
RUN javac Hello.java
CMD ["java", "Hello"]Build and push:
docker build -t yourdockerhubusername/hello-java:latest .
docker login
docker push yourdockerhubusername/hello-java:latestStep 4: Host a Flask App with Docker
Clone the sample app:
git clone https://github.com/LondheShubham153/flask-app-ecs
cd flask-app-ecsFix the version issue by editing requirements.txt (change flask=2.2.2 to flask).
Create Dockerfile:
FROM python:3.9
COPY . .
RUN pip install -r requirements.txt
CMD ["python", "app.py"]Build and run on port 80:
docker build -t flask-app .
docker run -d -p 80:80 flask-appStep 5: Use Volumes for Persistent Data
Avoid losing data when containers stop by mounting volumes.
Create a directory:
mkdir -p /home/ubuntu/volumes/mysql-dataRun MySQL with volume:
docker run -d -e MYSQL_ROOT_PASSWORD=my-secret-pw \
-v /home/ubuntu/volumes/mysql-data:/var/lib/mysql mysql:5.7Now your databases stay even if you restart the container.
Step 6: Connect Containers with Docker Networks
Create a network:
docker network create mynetworkRun database container inside network:
docker run -d --name mysql-db --network mynetwork \
-e MYSQL_ROOT_PASSWORD=my-secret-pw mysql:5.7Run Flask app in same network:
docker run -d -p 5000:5000 --network mynetwork \
-e MYSQL_HOST=mysql-db flask-appStep 7: Use Docker Compose to Manage Multi-Container Apps
Docker Compose makes multi-container apps simple.
Create docker-compose.yml:
version: "3"
services:
web:
build: .
ports:
- "80:80"
db:
image: mysql:5.7
environment:
MYSQL_ROOT_PASSWORD: my-secret-pwStart everything:
docker-compose up -dStep 8: Scan Your Images with Docker Scout
Check for vulnerabilities:
mkdir scout && cd scout
curl -sSfL https://raw.githubusercontent.com/docker/scout-cli/main/install.sh | sh
docker scout quickview yourdockerhubusername/hello-java:latestKeep exploring. Continue reading on our blog.
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