Docker Series — Part 10: Building Custom Docker Images for Apache Web Servers

In this post, we move beyond just running containers. We explore how to build your own custom Docker image, step by step — using both docker commit and the more powerful, structured approach: Dockerfile.
You’ll also learn the difference between build-time and run-time instructions — and how to automate container behavior from the start.

Why Build Custom Docker Images?

We’ve all used docker run with public images. But what if you want:

• Your own Apache web server setup?

• Pre-configured files inside the container?

• Automation during container startup?

That’s where building custom images comes in — and you have two ways to do it:

1. Using docker commit (manual snapshot)

2. Using a Dockerfile (declarative and reusable)

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Method 1: Using docker commit

This method is like taking a snapshot of a container after configuring it manually.

Step-by-step:

1. Run a container from CentOS:

    docker run -it centos:7
   

2. Install Apache inside the container:

    yum install httpd -y
   

3. Create your webpage:

    cd /var/www/html
    echo "vimal daga" > vimal.html
   

4. Start the Apache server:

    httpd
   

5. Exit the container, then:

    docker ps -a
    docker commit <container-id> myweb:v1
   

Now you’ve created a custom image from a live container. But this is manual — and not ideal for scaling or CI/CD.

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📦 Method 2: Using a Dockerfile (Recommended)

A Dockerfile lets you define everything in code — like infrastructure-as-code for containers. Here’s how:

🧱 Sample Dockerfile:

#Dockerfile
FROM centos:7

RUN yum install httpd -y

WORKDIR /var/www/html

RUN echo "vimal daga" > index.html

CMD ["/usr/sbin/httpd", "-D", "FOREGROUND"]

FROM: base image
RUN: install packages or run commands (build-time)
WORKDIR: set working directory
CMD: default command when container starts (run-time)

Build your image:

docker build -t myweb:v1 .

Run your container:

docker run -it myweb:v1

Now when the container launches:

• Apache is already installed

• HTML file is in place

• Web server auto-starts

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COPY vs docker cp

• docker cp is used manually:

    docker cp index.html container_id:/var/www/html/
  

• COPY in Dockerfile is better for automation:

    #Dockerfile
    COPY index.html /var/www/html/
  

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Build-Time vs Run-Time Commands

This distinction is key when optimizing and automating Docker workflows.

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Bonus Tip: Validate the Apache Process

Use ps aux inside your container to confirm:

ps aux | grep httpd

You’ll see the root + multiple Apache worker processes. That’s your web server in action

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Recap

In this blog, you learned:

• How to build custom Docker images in 2 ways

• How to create and start an Apache web server in a container

• Difference between RUN and CMD

• Dockerfile structure and key instructions

• Real-world automation for web hosting inside Docker

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Still confused about image builds or when to use which command?
Ping me anytime — I’d love to help you level up!

#Docker #DevOps #Dockerfile #Apache #WebServer #Containerization #Linux #InfrastructureAsCode #DockerSeries #LearningInPublic #OpenSource #CloudNative #DockerBuild