dev-ops-challenges

Git Stash

Technical Overview

During the software development lifecycle, engineers frequently need to switch tasks quickly—for example, to resolve a critical bug in production while working on a half-finished local feature. Committing half-baked, broken code to a branch just to switch branches is bad practice. Git provides the git stash command to solve this exact problem.

What is Git Stash and Why is it Needed?

git stash takes the dirty state of your working directory (your modified tracked files and staged changes) and saves it on a stack of unfinished changes that you can reapply at any time.

When is it Needed?

Context Switching: Quickly moving to another branch to work on a hotfix without losing your current, incomplete changes.
Pulling Remote Updates: Stashing local changes to perform a clean git pull from remote tracking branches, preventing local conflicts.
Experimenting Safely: Saving a working state before trying a risky code change, allowing a quick rollback if the experiment fails.

How Does Git Stash Work?

Under the hood, Git Stash saves your changes on a stack structure. Each stash is saved as a commit object in your local repository but is not attached to any active branch tip.

Stashes are indexed as stash@{0}, stash@{1}, stash@{2}, etc.
stash@{0} is always the most recently created stash (Last-In, First-Out stack order).
Stashing reverts your working directory back to a clean HEAD state.

sequenceDiagram
    participant WD as Working Directory
    participant Index as Staging Area
    participant Commit as Commit History
    participant Stash as Stash Stack
    
    Note over WD,Index: Developer has dirty, uncommitted changes
    WD->>Stash: git stash (Shelves modifications)
    Note over WD,Index: Working Directory is now clean (matches HEAD)
    
    Note over WD,Commit: Developer switches branches, makes hotfix commits
    
    Stash->>WD: git stash apply stash@{1} (Restores changes)
    Note over WD,Index: In-progress changes restored to workspace

Key Git Stash Commands

git stash / git stash save "message": Shelves staged and unstaged changes (excluding untracked files by default).
git stash -u / git stash --include-untracked: Shelves changes including untracked files (new files that haven’t been staged).
git stash list: Displays all stashed changes in the stack with their indexes and descriptions.
git stash apply stash@{n}: Restores the stashed changes at index n into the working directory but keeps the entry in the stash stack.
git stash pop stash@{n}: Restores the changes at index n and removes the entry from the stash stack.
git stash drop stash@{n}: Deletes the specified stash entry from the stack without applying it.
git stash clear: Deletes all stashed changes from the stack.

Infrastructure & Configuration Requirements

Target Host: Nautilus Storage Server (ststor01)
SSH User: natasha
Local Repo Path: /usr/src/kodekloudrepos/demo
Target Branch: master
Target Operation: Identify and restore the stash entry stash@{1}, then commit and push it.

Step-by-Step Implementation

Step 1: Connect to the Storage Server

From the Jump Host, SSH into the Nautilus storage server as natasha:

ssh natasha@ststor01

Step 2: Navigate to the Repository

Switch directory to the designated local Git repository:

cd /usr/src/kodekloudrepos/demo

Step 3: Inspect the Stash Stack

Display the list of currently stashed changes to identify the target index (stash@{1}):

git stash list

Example output:

stash@{0}: WIP on master: a2b3c4d Update landing page text
stash@{1}: WIP on master: f8e9d2c Add dynamic routing configurations
stash@{2}: WIP on master: 1d2f3e4 Initial documentation layout

We need to restore the stash at index 1 (stash@{1}).

Step 4: Apply the Target Stash

Restore the changes of stash@{1} to the active working directory:

git stash apply stash@{1}

Expected output:

On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   routing.js
	modified:   server.js

no changes added to commit (use "git add" and/or "git commit -a")

Step 5: Stage and Commit the Restored Changes

Stage all modified files and commit them with a descriptive message:

git add .
git commit -m "Apply routing configuration changes from stash@{1}"

Step 6: Push the Changes to Remote Origin

Push the new commit to the origin master branch:

git push origin master

Expected output:

Counting objects: 4, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (4/4), 415 bytes | 415.00 KiB/s, done.
Total 4 (delta 1), reused 0 (delta 0)
To /opt/demo.git
   a2b3c4d..4e8f9a2  master -> master

Post-Deployment Verification

1. Verify Remote Synchronization

Confirm that the commit was successfully pushed and the remote branch is in sync:

git log --oneline -n 3

Expected output showing the applied stash on top:

4e8f9a2 (HEAD -> master, origin/master) Apply routing configuration changes from stash@{1}
a2b3c4d Update landing page text
f8e9d2c Add dynamic routing configurations

2. Verify Working Directory Status

Ensure the working directory is clean:

git status

Expected output:

On branch master
Your branch is up to date with 'origin/master'.

nothing to commit, working tree clean

Log out of the Storage Server:

exit