Deployment triggers from tags in Git - Mini Project: Build & Apply

Deployment triggers from tags

📖 Scenario: You work in a team that uses Git for version control. Your team wants to automatically deploy the application only when a new tag is created. Tags are like labels on specific points in the project history, often used to mark releases.To make deployment automatic, you will write a simple Git hook script that triggers deployment only when a tag is pushed.

🎯 Goal: Create a Git hook script that triggers deployment only when a new tag is pushed to the repository.

📋 What You'll Learn

Create a Git hook script file named post-receive in the .git/hooks/ directory

Add a variable ref to capture the reference name from standard input

Write a condition to check if the ref starts with refs/tags/

Print Deploying tag: <tag_name> when a tag is pushed

💡 Why This Matters

🌍 Real World

Git hooks are used in real projects to automate tasks like deployment when code is pushed. Using tags to trigger deployment helps release stable versions automatically.

💼 Career

Understanding Git hooks and deployment triggers is important for DevOps roles to automate software delivery and improve team workflows.

1

Create the Git hook script file

Create a file named post-receive inside the .git/hooks/ directory with the first line as the shebang #!/bin/sh.

Git

# Create the file .git/hooks/post-receive and add the shebang line
# Your code here

Need a hint?

The first line of a shell script is usually #!/bin/sh to specify the shell interpreter.

2

Capture the reference name from standard input

Add a line to read the old revision, new revision, and reference name into variables oldrev, newrev, and ref using read oldrev newrev ref.

Git

#!/bin/sh
# Read oldrev, newrev, and ref from standard input
# Your code here

Need a hint?

Use the read command to get input from standard input into variables.

3

Check if the reference is a tag

Write an if statement that checks if the variable ref starts with refs/tags/ using case "$ref" in refs/tags/*) syntax.

Git

#!/bin/sh
read oldrev newrev ref
# Add if condition to check if ref starts with refs/tags/
# Your code here

Need a hint?

Use a case statement to match the pattern refs/tags/* for tags.

4

Print deployment message for the tag

Inside the case block for refs/tags/*, add a echo command that prints Deploying tag: <tag_name> where <tag_name> is the tag name extracted by removing the refs/tags/ prefix from ref using shell parameter expansion ${ref#refs/tags/}.

Git

#!/bin/sh
read oldrev newrev ref
case "$ref" in
  refs/tags/*)
    # Print deployment message
    # Your code here
    ;;
esac

Need a hint?

Use echo and shell parameter expansion ${ref#refs/tags/} to print the tag name.