Docker

How to Create a Docker Container: A Quick Guide

March 27, 2025

Wondering how to create a Docker container and make your application development smoother? Let’s get straight to it. Docker containers have changed application deployment, offering environments that ensure consistency across diverse platforms like AWS and Google Cloud Platform.

As someone who has dug deep into the mix of containerization and microservices architecture, I know the power Docker brings in speeding up DevOps and enhancing CI/CD pipelines.

Today, with tools like Docker Hub and Kubernetes, knowing how to create a Docker container stands as a crucial skill for any developer looking to grow and adapt to the changing world of software development.

In this guide, we’ll look into the basics: crafting a Dockerfile, understanding container orchestration, and managing images.

By the end, you’ll be equipped with practical steps and a newfound confidence to take your development projects to the next level. Ready to explore and truly learn what Docker can do for you? Let’s dive in.

How To Create A Docker Container: Quick Workflow

Creating a Docker container involves several steps: writing a Dockerfile, building a Docker image, and then running that image to create a container. Here’s a step-by-step guide:

Step 1: Write a Dockerfile

A Dockerfile is a text file that contains instructions for building a Docker image. It specifies the base image, copies files, sets environment variables, and defines the command to run when the container starts.

Example Dockerfile for a Python App:

# Use an official Python runtime as a parent image
FROM python:3.10-alpine# Set the working directory in the container
WORKDIR /code# Set environment variables
ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0# Install any needed packages specified in requirements.txt
COPY requirements.txt .
RUN pip install -r requirements.txt# Copy the application code
COPY . .

# Make port 5000 available to the world outside this container
EXPOSE 5000

# Define environment variable
ENV NAME World

# Run app.py when the container launches
CMD ["flask", "run", "--host=0.0.0.0"]

Step 2: Build a Docker Image

Use the Dockerfile to build a Docker image. Navigate to the directory containing your Dockerfile and run:

docker build -t my-python-app .

This command builds an image with the tag my-python-app.

Step 3: Create and Run a Docker Container

To create and run a container from the image, use the docker run command:

docker run -p 5000:5000 my-python-app

This command maps port 5000 on your local machine to port 5000 inside the container, allowing you to access the application from outside the container.

Alternatively, you can create a container without running it immediately using docker create, and then start it later:

docker create --name my-container my-python-app
 docker start my-container

Additional Commands

List all containers: docker ps -a
Stop a container: docker stop my-container
Remove a container: docker rm my-container

Building a Docker Container from Scratch

maxresdefault How to Create a Docker Container: A Quick Guide

Understanding Docker Images

What is a Docker Image?

A Docker image is basically a read-only template. It’s the blueprint for containers, defining the various software layers needed. Think of it as your master copy. These images are made up of a series of layers, each representing changes or additional software added to the image.

The Role of Docker Hub

Docker Hub plays host to public images. It’s a large repository where developers share setups. Grab pre-configured apps or base images here. Use it to reduce setup time by pulling what’s already made instead of starting from scratch.

Difference Between Images and Containers

Images sit on your disk, ready but not yet running. Containers, on the other hand, are the live workings—instances of these images in action. A container comes to life when you execute an image, holding everything an app needs to run.

Writing a Dockerfile

Structure and Syntax of a Dockerfile

A Dockerfile is a simple text file without a fuss. It tells Docker how to build an image. Commands go in uppercase, starting with a keyword like FROM, COPY, and so on. Each line represents an instruction—one step in your image creation.

Choosing a Base Image (FROM Instruction)

Start your Dockerfile with FROM. Pick a base that fits your project’s needs, like alpine for lightweight essentials or ubuntu for a more comprehensive environment. This base serves as the foundation.

Adding Files and Directories (COPY and ADD)

Use COPY and ADD to inject files into your image. COPY is straightforward—good for local files. ADD can handle URLs and compressed files.

Installing Software Packages (RUN)

RUN commands execute during image building, installing needed software. It’s where dependencies come together. Often, regular package managers handle installations here.

Setting Up Environment Variables (ENV)

With ENV, declare settings your app requires, like ENV PORT 3000. Less hassle, more control—just the way we like it.

Defining the Default Command (CMD vs. ENTRYPOINT)

Instruct Docker what to execute using CMD or ENTRYPOINT. CMD is the default if no command is set while running the container. ENTRYPOINT makes sure it always runs a specific command, with CMD providing default parameters.

Building the Docker Image

Using docker build to Create an Image

To build an image, hop into the terminal. Use the docker build command. It reads your Dockerfile, layer by layer, creating the image you need.

Naming and Tagging an Image

Easily identify your creation with a meaningful name and tag. docker build -t myapp:latest gives your image a proper label.

Optimizing the Image for Performance

Efficiency is king. Merge commands to reduce layers, keep images slim and maintainable, and choose compact base images like alpine.

Viewing and Managing Built Images (docker images)

List what you’ve crafted using docker images. You’ll see details on your creations—names, tags, sizes—all lined up and ready. Stop here without further explanation.

Running and Managing Docker Containers

Creating and Running a Container

Using docker create to Set Up a Container

The docker create command gets a container ready, like setting a table. Specify the image you want. Docker assigns an ID, quietly mapping out your app’s future home. Some customization happens here, like setting environment variables.

Starting and Running a Container (docker run)

Now, bring it to life with docker run. The heart of Docker’s charm is right here. It does double duty as it creates and starts. Just hit the command, and watch it spin into action. Whether you need a simple server or a complex microservice architecture, it’s ready.

Interactive vs. Detached Mode (-it vs. -d)

Modes matter. Toss an -it into docker run for interaction—terminal input, live tweaks. Useful for debugging and experimentation. If your mind’s elsewhere, use -d for detached. It fades into the background, much like a careful observer in a busy café.

Managing Running Containers

Viewing Running Containers (docker ps)

Lists are satisfaction. docker ps serves them up—running containers, their states, ports. It lets you peek at your container kingdom, discerning which subjects are actively working.

Stopping and Restarting Containers (docker stop/start)

Pause or relaunch containers as you please. docker stop [container_id] quietly halts operations. Need a restart? Hop on the docker start [container_id] train, back to work with minimal fuss. It’s flexibility at its core—a nimble way to keep digital processes in check.

Checking Logs and Resource Usage (docker logs, docker stats)

Analyze with docker logs. Unravel the tale of each container, issue by issue. For a sharper glance at performance, docker stats displays CPU, memory, and more. A digital saucepan check—enough ingredients?

Configuring Container Networking

Port Mapping (-p Option)

Unmap those doors. With -p, tell Docker which ports to open. 80:8080 could be your server’s invitation to the wider world. It’s not magic, just simple redirection.

Connecting Containers to a Network (docker network create/connect)

Need interaction between containers? Use docker network create to build, then docker network connect to link them. Microservices hum along, sipping data and passing packets in neat little lines.

Exposing Services Within a Container

Bring internals out with docker expose. It’s about showing the right service, keeping doors open or shut. It manages communication while keeping auth intimate.

Persistent Storage in Docker Containers

Understanding Volumes vs. Bind Mounts

Two choices for storage: Volumes and bind mounts. Volumes, managed by Docker, make swaps easy. Bind mounts directly access host paths. Decision hinges on control needs.

Creating and Attaching Volumes (docker volume create)

Go with docker volume create. Hook it to a container with --mount. Data lives safely beyond single container lifetimes, not lost in ephemeral states.

Cross-container sharing. Declare storage as public domain, used collaboratively. Keeps the necessary mutual knowledge when containers play together in a sandbox of devops delight.

Optimizing Docker Container Management

Best Practices for Docker Containers

Keeping Containers Lightweight

Start with a lean base image like Alpine. This means less bloat, faster spins. Prune irrelevant packages—every megabyte counts.

Using Official and Trusted Images

Stick to verified sources. Docker Hub provides official images. Avoid the unknowns; known images mean fewer vulnerabilities.

Minimizing the Number of Layers in a Dockerfile

Combine RUN commands where possible. Fewer layers streamline the image, trimming sizes down. Efficient, effective—get it done without the extras.

Cleaning Up Unused Images and Containers (docker system prune)

Jettison the junk. docker system prune clears the clutter. Old containers and images stacked up? Time for a digital sweep.

Enhancing Security in Docker Containers

Running Containers with Least Privileges (USER Instruction)

Never run as root. Use USER to define execution privileges. Limit rights and keep security tight.

Securing Sensitive Data with Environment Variables

Extend secrets into environment variables. This way, passwords don’t linger in images. Control through ENV for safety.

Limiting Container Permissions (–read-only, –cap-drop)

Make containers read-only when you can. Use --cap-drop to strip unnecessary privileges, ensuring operations stay limited and locked.

Scaling and Orchestration

Using Docker Compose for Multi-Container Applications

Docker Compose simplifies the orchestration of multiple containers. Use docker-compose.yml to define services, making complex setups less daunting. One command, many applications.

Introduction to Container Orchestration with Kubernetes

Step into container orchestration with Kubernetes. It’s about automatic deployment, scaling, and management. Mastering Kubernetes means control over vast container fleets.

Deploying and Distributing Docker Containers

Pushing and Pulling Images to Docker Hub

Tagging Images for Repository Use

Before you send off your image, tag it—docker tag myapp:latest username/myapp:version. This makes it identifiable on Docker Hub, your repository’s face, so to speak.

Using docker push to Upload an Image

Push it. Hit the command docker push username/myapp:version. This uploads your image to Docker Hub. Once there, it’s available globally, for anyone or just you, depending on privacy settings.

Pulling an Image from Docker Hub (docker pull)

Grab an image with docker pull. Maybe it’s one of those official and trusted images. Or maybe it’s yours. Either way, Docker Hub allows quick, on-demand access.

Running Containers in Production Environments

Using Docker in Cloud Platforms

AWS ECS, Google Kubernetes Engine (GKE), Azure Kubernetes Service (AKS)—big names, right? They’ve got slots for Docker containers. Scaling, deploying—all things cloud are one command line away.

Managing Docker Containers on a Virtual Private Server (VPS)

VPS provides a sandbox. Your space. Place those containers here for full control. It’s cost-effective, good for testing, and self-managed at the base. Remember, a little automation might save time.

Automating Container Deployment with CI/CD

Continuous Integration, Continuous Deployment—CI/CD—streamline operations. Systems like Jenkins, GitLab CI/CD integrate well with Docker, shooting code straight from repository to deployment without hiccups. Automation brings efficiency; it keeps the ecosystem smooth.

FAQ on How To Create A Docker Container

What is a Docker container?

A Docker container is a lightweight, standalone, and executable software package that includes everything you need to run a piece of software.

This includes the code, runtime, system tools, libraries, and settings. Containers provide consistent environments from development to production in platforms like AWS or Google Cloud Platform.

How do I start creating a Docker container?

To start, you’ll need Docker installed on your system. Then, you’ll craft a Dockerfile to specify the environment and dependencies.

This Dockerfile can then be used to build a Docker image, which can be run as a container. It’s straightforward. Just follow each step.

What is a Dockerfile?

A Dockerfile is a text document containing all the commands to assemble an image. With a few lines of code, you define the image’s base, copy application code, and set environment variables. It’s your blueprint for creating repeatable containers—crucial for DevOps teams focusing on automation.

How do I run a Docker container?

Use the docker run command. This spins up a new container from a Docker image. You’ll specify options like port mapping and volume management to control how the container interacts with other parts of your system. Want to start MySQL? docker run mysql—and you’re on your way.

What is Docker Hub?

Docker Hub is an online space for sharing and managing Docker images. It’s like a library for images, providing both official and community-driven options.

Pull images, such as Nginx or Redis, and push your creations to share with others. It’s key for collaborative container projects.

How do I manage container networking?

Docker handles internal networking automatically. However, for external communication, use networking flags in your run command, like -p for port mapping.

Docker virtualizes network interfaces, providing tools like Swarm mode for higher-level management of network configurations.

Can I use Docker with existing virtual machines?

Yes, but it’s not a common practice, since Docker containers offer a different approach. Containers are lightweight and share the host system’s kernel, while VMs come with their own OS. Running containers in a VM might suit specific workflows needing isolated environments.

To share, push your image to Docker Hub or any container registry. This registers it in a repository, making it accessible to others.

Team members can pull the image and run consistent environments locally. Collaboration in large projects is made easy, especially in a CI/CD pipeline.

What are environment variables in Docker?

Environment variables allow you to pass data into your Docker containers, setting dynamic information like database credentials and API keys.

They adjust a container’s behavior without changing the code. Use the -e flag in your docker run command to specify these variables.

Why is security important in Docker?

Adopting best security practices ensures your containers remain safe from vulnerabilities. Use minimal base images, scan regularly for issues, and manage permissions wisely. Security is a continuous process—never static. It keeps your applications safe in a world of evolving threats.

Conclusion

Creating a Docker container isn’t just a matter of code; it’s about building a trusted environment for your projects. How to create a Docker container is the first step towards reliable application deployment across platforms like Microsoft Azure and IBM Cloud. You’ve got the basics down: writing a Dockerfile, running images, managing networking, and securing your setup.

Now, embrace these tools. They’re not just tech, but essential elements of modern software development. With your newfound skills, bring your ideas to life. From container management to scaling, each step can make an impact. Whether it’s deploying a Nginx instance or managing databases like MySQL, your journey has only begun.

Ready to expand your mastery? Keep exploring. Learn more about container orchestration, tie it all together with Kubernetes, and push boundaries. Your path with Docker is a forward one, filled with potential for enhancement and discovery. Keep building, keep growing, and use every tool at your disposal.

If you liked this article about how to create a Docker container, you should check out this article about how to stop Docker container.

There are also similar articles discussing how to remove Docker images, how to install Docker compose, how to restart a Docker container, and how to ssh into Docker container.

And let’s not forget about articles on how to exit Docker container, how to check if Docker is running, how to install Docker, and how to start Docker daemon.

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Bogdan Sandu

Bogdan is a seasoned web designer and tech strategist, with a keen eye on emerging industry trends.

With over a decade in the tech field, Bogdan blends technical expertise with insights on business innovation in technology.

A regular contributor to TMS Outsource's blog, where you'll find sharp analyses on software development, tech business strategies, and global tech dynamics.