Chapter 2: Git, GitHub and Git Bash

2.13 Lab — three commits and one remote

By Ravindra Bagale · Last updated: 25 October 2026

Why: the problem

Now you will put everything from this chapter together, the way you would on your first week in a job. Your lead at a Pune company asks: "Create the hello-shop repo, make three clean commits, ignore secrets, and push it to our GitLab so CI can pick it up." This is a real task. It checks if you can do init, status, add, commit, .gitignore, log, undo and remote setup without help. In this lab you will do it start to end, with a check after every step, then prove it works by cloning the repo fresh into a new folder, like a CI runner would. If anything goes red, the fix is shown right there.

What we will build

You will build hello-shop from zero: three meaningful commits, a .gitignore and .env.example, one safe undo, a remote on gitlab.com over SSH, a push, and a fresh clone that runs the app and passes the health check.

What: every term in plain English

• Lab — A hands-on exercise that joins many lessons into one real task.
• Meaningful commit — A commit with one idea and a clear message.
• Fresh clone — A new copy from the server, like CI would make.
• Health check — A small URL that says ok when the app is alive.
• Upstream — The remote branch your local branch tracks.
• Clean tree — No unsaved changes.
• Evidence — Output you save to prove the work, such as git log and curl results.
• Runbook — A short page with the exact commands to repeat the work.

How: step by step

1. Start fresh

   mkdir -p ~/devops-lab/final && cd ~/devops-lab/final && git init -b main
   

   What it does: A new repo.

   Output

   Initialized empty Git repository in /home/ravi/devops-lab/final/.git/
   

2. Commit 1: app

   (copy app.py from 2.5 with the /health route) git add app.py && git commit -m "Add hello-shop app with health route"
   

   What it does: The code.

   Output

   [main (root-commit) 1111111] Add hello-shop app with health route
   

3. Commit 2: rules

   (write .gitignore and .env.example from 2.8) git add .gitignore .env.example && git commit -m "Ignore secrets and add env sample"
   

   What it does: Protect secrets.

   Output

   [main 2222222] Ignore secrets and add env sample
   

4. Commit 3: docs

   (write README.md) git add README.md && git commit -m "Add README with run and test steps"
   

   What it does: Teach others.

   Output

   [main 3333333] Add README with run and test steps
   

5. Check

   git log --oneline && git status --short
   

   What it does: Three commits, clean tree.

   Output

   3333333 Add README with run and test steps
   2222222 Ignore secrets and add env sample
   1111111 Add hello-shop app with health route
   

6. Add remote and push

   git remote add origin git@gitlab.com:ravi-learner/final.git && git push -u origin main
   

   What it does: Shared with the team.

   Output

   To gitlab.com:ravi-learner/final.git
    * [new branch]      main -> main
   

7. Fresh clone test

   cd /tmp && git clone -q git@gitlab.com:ravi-learner/final.git final-ci && cd final-ci && ls -a
   

   What it does: A CI-like copy. No .env.

   Output

   .  ..  .env.example  .git  .gitignore  README.md  app.py
   

Example 1: Run the whole lab as one script

Stack. Bash, Git

Goal. Run the whole lab as one script.

lab.sh

#!/usr/bin/env bash
set -euo pipefail
R=~/devops-lab/final
rm -rf "$R" && mkdir -p "$R" && cd "$R"
git init -q -b main
cp ~/devops-lab/hello-shop/app.py .
git add app.py && git commit -qm "Add hello-shop app with health route"
printf ".env\n__pycache__/\n*.log\n" > .gitignore
printf "APP_PORT=8000\n" > .env.example
git add .gitignore .env.example && git commit -qm "Ignore secrets and add env sample"
printf "# hello-shop\nRun: python3 app.py\nTest: curl localhost:8000/health\n" > README.md
git add README.md && git commit -qm "Add README with run and test steps"
echo "SECRET=1" > .env
git status --short
git log --oneline

What each line does

• set -euo pipefail — Stop on any error.
• rm -rf "$R" — Start clean each time. Only the lab folder.
• printf ... > .gitignore — Rules without a heredoc.
• echo "SECRET=1" > .env — Test that the secret is ignored.
• git status --short — Should print nothing.

Green output

3333333 Add README with run and test steps
2222222 Ignore secrets and add env sample
1111111 Add hello-shop app with health route

Expected result. Three commits and the secret file is invisible to Git.

Example 2: Prove the fresh clone works like CI

Stack. Git, Python, curl

Goal. Prove the fresh clone works like CI.

ci-check.sh

cd /tmp && rm -rf final-ci
git clone -q --depth 1 git@gitlab.com:ravi-learner/final.git final-ci
cd final-ci
test ! -f .env && echo "no secret in repo"
python3 app.py > app.log 2>&1 &
sleep 1
curl -fsS localhost:8000/health
kill %1

What each line does

• --depth 1 — Shallow, like CI.
• test ! -f .env — The secret must not come from Git.
• python3 app.py & — Start the app.
• curl -fsS .../health — Fails the script if not ok.
• kill %1 — Stop the app.

Green output

no secret in repo
ok

Expected result. Anyone, or any CI job, can clone and run your repo from the README alone.

Example 3: Practise one safe undo inside the lab

Stack. Git

Goal. Practise one safe undo inside the lab.

undo.sh

cd ~/devops-lab/final
sed -i 's/8000/9000/' README.md
git commit -qam "Change port in README"
git push -q
git revert --no-edit HEAD
git push -q
git log --oneline -2
grep -c 8000 README.md

What each line does

• Wrong port — A bad change pushed on purpose.
• git revert — The safe undo for pushed work.
• git push — Share the fix.
• grep -c 8000 — The right port is back.

Green output

4444444 Revert "Change port in README"
5555555 Change port in README
1

Expected result. You fixed a shared mistake without force push.

Verify: did it work?

1. Remote has 5 commits

   git ls-remote origin main && git rev-list --count HEAD
   

   What it does: Server and laptop match.

   Output

   4444444...  refs/heads/main
   5
   

2. No secret tracked

   git ls-files | grep -c "^.env$" || true
   

   What it does: 0.

   Output

   0
   

3. Clean

   git status -sb
   

   What it does: In sync.

   Output

   ## main...origin/main
   

When it is red 1

error: src refspec main does not match any

Cause. You tried to push before any commit, or the branch is named master.

Fix, step by step

1. git log to check commits.
2. git branch -m master main if needed.

When it is red 2

git@gitlab.com: Permission denied (publickey).

Cause. SSH key not added.

Fix, step by step

1. Follow lesson 2.12 to add the key, or use the HTTPS URL with a token.

When it is red 3

curl: (7) Failed to connect to localhost port 8000

Cause. The app did not start, often because the port is in use.

Fix, step by step

1. cat app.log
2. ss -ltnp | grep 8000
3. Stop the other process and retry.

Cleanup

1. Remove local lab copies

   rm -rf ~/devops-lab/final /tmp/final-ci
   

   What it does: The gitlab.com project stays for your portfolio.

   Output

   (no output)
   

Practice tasks

Homework: try at home

Recap

• Three focused commits tell a clean story.
• .gitignore and .env.example protect secrets.
• Push with SSH or a token.
• A fresh clone proves the repo works for CI.
• Use revert for pushed mistakes.

FAQ

Can I do the lab on Windows?

Yes, in Git Bash. Use python instead of python3 if needed.

Must the repo be public?

No. Private is fine. CI uses a deploy key or token.

What if my company uses git.example.com?

Same steps. Only the remote URL changes.

Should I delete the gitlab.com project after?

Keep it. It shows your work to interviewers.

What next?

Chapter 3: branches, merge requests, conflicts and rebase.

Interview questions

1. Describe how you set up a new repo for a team.

   git init, clear first commits, .gitignore and env sample, README, remote over SSH, push, and a fresh clone check.

2. How do you make sure no secrets are in a repo?

   .gitignore, pre-commit checks, reviewing git diff --staged, and scanning tools in CI.

3. How do you check a repo works for CI?

   Clone it fresh and shallow, run the documented commands and a health check.

4. What is your Git flow for a small fix?

   status, add the file, commit with a clear message, pull --rebase, push.

5. How do you undo a pushed mistake?

   git revert and push.

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