Pushing images from CI in Docker - Mini Project: Build & Apply

Pushing Docker Images from CI

📖 Scenario: You work in a team that builds Docker images for your app. You want to automate pushing these images to Docker Hub using a Continuous Integration (CI) pipeline.This project guides you to write a simple Dockerfile, set up image tagging, and push the image to Docker Hub from a CI script.

🎯 Goal: Build a Docker image from a Dockerfile, tag it with a version, and push it to Docker Hub using a CI script.

📋 What You'll Learn

Create a Dockerfile with a simple base image

Set a variable for the image tag

Write a command to build and tag the Docker image

Write a command to push the tagged image to Docker Hub

💡 Why This Matters

🌍 Real World

Automating Docker image builds and pushes saves time and avoids manual errors in software delivery.

💼 Career

CI pipelines that build and push Docker images are common tasks for DevOps engineers and developers working with containerized apps.

1

Create a simple Dockerfile

Create a file named Dockerfile with these exact contents:
FROM alpine:3.18
CMD ["echo", "Hello from Docker"]

Docker

# Create a Dockerfile with FROM alpine:3.18 and CMD ["echo", "Hello from Docker"]

Need a hint?

This Dockerfile uses Alpine Linux as the base and prints a message when run.

2

Set the image tag variable

In a file named ci_script.sh, create a variable called IMAGE_TAG and set it to "myapp:1.0".

Docker

FROM alpine:3.18
CMD ["echo", "Hello from Docker"]

# Set IMAGE_TAG variable
# Your code here

Need a hint?

Use IMAGE_TAG="myapp:1.0" exactly to set the tag.

3

Build and tag the Docker image

In ci_script.sh, add a command to build the Docker image from the current directory and tag it with $IMAGE_TAG.

Docker

FROM alpine:3.18
CMD ["echo", "Hello from Docker"]

IMAGE_TAG="myapp:1.0"

# Build and tag the Docker image
# Your code here

Need a hint?

Use docker build -t $IMAGE_TAG . to build and tag the image.

4

Push the Docker image to Docker Hub

In ci_script.sh, add a command to push the Docker image tagged with $IMAGE_TAG to Docker Hub.

Docker

FROM alpine:3.18
CMD ["echo", "Hello from Docker"]

IMAGE_TAG="myapp:1.0"

docker build -t $IMAGE_TAG .

# Push the Docker image
# Your code here

Need a hint?

Use docker push $IMAGE_TAG to push the image.