vanshikamunjal665-containerization-theory.github.io

CONTAINERIZATION AND DEVOPS THEORY

06 FEBRUARY 2026

SINGLESTAGE DOCKERFILES

Screenshots of commands

Dockerfile (Singlestage)
Image

C Hello World Code
Image

Running Demon
Image Image

Image

Image

Image

1. Enter wsl

wsl

2. Changing directory

cd "/mnt/c/Users/Vanshika Munjal/Desktop/Containerization-Theory/class-task-6Feb"

3. Renaming the file from Dockerfile.txt to Dockerfile

mv Dockerfile.txt Dockerfile

4. Building image from Dockerfile

docker build -t c-app:1.0 .

docker build → build an image from a Dockerfile
-t c-app:1.0 → tag the image
c-app = image name
1.0 = version
. → current directory contains the Dockerfile
So Docker looks for a file named Dockerfile in this folder.

5. Starting container

docker run -it c-app:1.0

Container starts CMD [”./hello”] executes

6. List all Docker images present on the system

docker images

Dockerfile Code Explanation

FROM ubuntu:22.04 AS build Uses Ubuntu 22.04 as the base image and names this stage build.

RUN apt-get update && apt-get install -y gcc Updates package lists and installs the GCC compiler inside the image.

COPY hello.c . Copies the C source file from the host system into the container.

RUN gcc -static -o hello hello.c Compiles the C program into a statically linked executable named hello.

# Problem: Includes entire Ubuntu + gcc in final image Comment indicating that this approach results in a large image containing unnecessary build tools.

CMD ["./hello"] Specifies the default command to run the compiled program when the container starts.

Conclusion

In a single-stage Docker build, the same image is used for both building and running the application, which makes the process simple but results in a large image size because the final image includes unnecessary components such as the operating system and build tools (e.g., GCC).