Build and Release Engineer Interview Questions &amp; Answers

Show answer

git stash saves your uncommitted changes and cleans the working directory, so you can switch branches for an urgent fix. git stash list shows saved entries, git stash pop reapplies the latest and removes it, and git stash apply keeps it. Use git stash -u to include untracked files. It is a short-term tool; for longer work, commit on a branch.

What is the difference between a hard link and a soft link?

Show answer

A hard link is another directory entry pointing to the same inode, so the data survives until every hard link is deleted; it cannot cross file systems or point to directories. A soft (symbolic) link is a small file that stores a path to the target; it can cross file systems and point to directories, but it breaks if the target is moved or deleted.

What is an artefact repository and why is it used?

Show answer

An artefact repository such as Nexus, JFrog Artifactory or a container registry stores versioned build outputs like JAR files, npm packages and Docker images. The pipeline builds once and promotes the same artefact through dev, staging and production, so what you tested is exactly what you deploy. It also caches public dependencies, speeds up builds and keeps release history for rollbacks.

What does git cherry-pick do?

Infrastructure as Code (Terraform and Ansible)Easy

Show answer

git cherry-pick <hash> applies the changes of one specific commit onto your current branch as a new commit. It is useful to bring a hotfix from main into a release branch without merging everything else. Overusing it creates duplicate commits with different hashes and can cause confusing conflicts later, so prefer merging when you need a whole set of changes.

What is Infrastructure as Code and what are its benefits?

Show answer

Infrastructure as Code means defining servers, networks, databases and other resources in version-controlled files instead of clicking in a console. Benefits are repeatable environments, code review for infrastructure changes, history and rollback through Git, fewer manual mistakes, faster provisioning and easy disaster recovery. Common tools are Terraform and OpenTofu for provisioning and Ansible for configuration management.

What are zombie and orphan processes?

Show answer

A zombie is a process that has exited but whose parent has not yet read its exit status with wait(), so it still holds a PID entry and shows state Z. An orphan is a running process whose parent died; it is adopted by PID 1, which reaps it later. Many zombies indicate a buggy parent; fixing or restarting the parent clears them.

What is the difference between kill, kill -15 and kill -9?

Show answer

kill sends SIGTERM (15) by default, which asks the process to stop so it can close files, finish requests and clean up. kill -9 sends SIGKILL, which the kernel enforces immediately; the process cannot catch it, so data may be lost and temp files left behind. Always try SIGTERM first and use SIGKILL only when the process does not respond.

What is the difference between continuous integration, continuous delivery and continuous deployment?

Show answer

Continuous integration means developers merge small changes often and every merge is automatically built and tested. Continuous delivery goes further: every passing build is packaged and ready to release, but a human approves the production push. Continuous deployment removes that manual step, so every change that passes all checks goes to production automatically. Each stage needs more test confidence than the last.

How do you find files larger than 100 MB and older than 7 days under /var/log?

Show answer

find /var/log -type f -size +100M -mtime +7 -exec ls -lh {} + # compress them instead of just listing find /var/log -type f -size +100M -mtime +7 -exec gzip {} + -size +100M matches files above 100 MB, -mtime +7 means modified more than 7 days ago, and -exec with + passes many files to one command call, which is faster than running it once per file.

Explain the Linux boot process briefly.

Linux and Shell ScriptingHard

Show answer

The firmware (BIOS or UEFI) runs hardware checks and loads the bootloader, usually GRUB. GRUB loads the kernel and the initramfs, which contains drivers needed to mount the real root file system. The kernel then starts PID 1, which is systemd on most modern distributions. systemd mounts file systems and starts services in parallel according to unit dependencies and the default target.

What is the difference between sudo and su?

Show answer

su switches to another user, usually root, and needs that user's password, giving a full shell as them. sudo runs a single command with elevated rights using your own password, and is controlled by rules in /etc/sudoers. sudo is preferred in teams because each action is logged against the real user and access can be limited to specific commands.

How do you view the commit history in a compact graph form?

Show answer

git log --oneline --graph --decorate --all # last 10 commits by one author git log --oneline -10 --author="Ravi" # commits touching one file, with diffs git log -p -- src/app.py # who changed each line git blame src/app.py --graph draws branch and merge lines, and --decorate shows branch and tag names next to commits.

What are the typical stages of a CI/CD pipeline?

Show answer

A common pipeline is checkout, build or compile, unit tests, static analysis and security scans, packaging into an artefact or container image, pushing to a registry, deploying to a test or staging environment, running integration or smoke tests, an approval gate, and production deployment with monitoring. Fast checks run first so developers get feedback within minutes and slow tests run later.

What is Git and how is it different from GitHub?

Show answer

Git is a distributed version control system that tracks changes to files; every clone has the full history and works offline. GitHub is a hosting service built around Git that adds remote repositories, pull requests, code review, issues and Actions for CI. Alternatives such as GitLab and Bitbucket offer similar features. You can use Git without GitHub, but not the other way round.

What is .gitignore and how do you stop tracking a file that is already committed?

Show answer

A .gitignore file lists patterns such as node_modules/, *.log or .env that Git should not track. It only affects untracked files, so a file already committed keeps being tracked. To stop tracking it, run git rm --cached <file>, add it to .gitignore and commit. If it held a secret, the old commits still contain it and the secret must be rotated.

A production deployment failed halfway. What do you do?

Show answer

Assess impact quickly using monitoring and error rates. If users are affected, roll back to the last good version, which should be a single pipeline action redeploying the previous artefact. Communicate status to stakeholders. Then check pipeline logs and application logs to find the cause, fix it in a branch and redeploy. Afterwards, hold a blameless review and add a check to catch it earlier.

How do you manage secrets in a CI/CD pipeline?

Show answer

Never store secrets in code or the Jenkinsfile. Use the CI tool's encrypted credentials store, such as Jenkins credentials or GitHub Actions secrets, or fetch them at runtime from HashiCorp Vault or AWS Secrets Manager. Prefer short-lived credentials, for example OIDC federation from GitHub Actions to AWS instead of long-lived keys. Mask secrets in logs and give each pipeline only the permissions it needs.

How do you handle pressure when a release is blocked close to a deadline?

Show answer

Situation: a security scan blocked our release one day before a client demo. Task: ship without ignoring the risk. Action: I checked the finding, confirmed it was a real vulnerable library, upgraded it, ran the full test suite and kept the product manager updated every few hours. Result: we released on time, and I added weekly dependency scans to avoid last-minute surprises.

How do you make your commits and pull requests easy for teammates to review?

Show answer

I keep each pull request focused on one change and small enough to review in about fifteen minutes. Commits have clear messages saying what and why. The description explains the problem, the approach, how I tested it and any risk or rollback step. I run linters and tests locally first, and I reply to every review comment, even if just to say done.

What is the difference between git revert and git reset?

Git and Version ControlMedium

Show answer

git revert creates a new commit that undoes the changes of an earlier commit, leaving history intact, so it is safe on shared branches like main. git reset moves the branch pointer backwards and removes commits from the branch history, which is fine locally but forces others to deal with rewritten history if already pushed. Use revert for anything already public.

What is the difference between COPY and ADD in a Dockerfile?

Docker and ContainersEasy

Show answer

COPY copies local files and directories into the image and does nothing else. ADD can also download from a URL and automatically extracts local tar archives. Because that extra behaviour can be surprising, best practice is to use COPY by default and ADD only when you specifically want tar extraction. For downloads, use curl in a RUN step so you can verify checksums.

How do you undo the last commit but keep the changes?

Show answer

git reset --soft HEAD~1 # undo commit, keep changes staged git reset HEAD~1 # undo commit, keep changes unstaged # only fix the message or add a missed file git add missed-file.txt git commit --amend Use these only on commits not yet pushed. For a pushed commit on a shared branch, use git revert instead.

Explain Linux file permissions and what chmod 755 means.

Show answer

Every file has read (4), write (2) and execute (1) bits for three classes: owner, group and others. chmod 755 gives the owner 7 (read, write, execute) and gives group and others 5 (read, execute). It is typical for scripts and directories that everyone may run or enter but only the owner may change. Use ls -l to see permissions.

What is the difference between git fetch and git pull?

Show answer

git fetch downloads new commits and branches from the remote into remote-tracking branches like origin/main without touching your working files. git pull is fetch followed by merge (or rebase if configured) into your current branch. Fetch is safer when you want to inspect incoming changes first with git log main..origin/main before integrating them.

Write a GitHub Actions workflow that runs tests on every pull request.

Show answer

name: CI on: pull_request: branches: [main] jobs: test: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: npm - run: npm ci - run: npm test Add this as .github/workflows/ci.yml and make the job a required status check in branch protection.

Tell me about a time you had to learn a new cloud service quickly.

AWS Cloud for DevOpsEasy

Show answer

Situation: in my internship, the team needed a scheduled job and asked me to use AWS Lambda, which I had never used. Task: deliver it in a week. Action: I went through the official docs and a hands-on tutorial, built a small proof of concept on day two, and asked a senior to review the IAM role. Result: the job went live on time and I documented the setup.

Write a declarative Jenkinsfile with build, test and deploy stages.

Show answer

pipeline { agent { label 'linux' } stages { stage('Build') { steps { sh 'mvn -B clean package -DskipTests' } } stage('Test') { steps { sh 'mvn -B test' } post { always { junit 'target/surefire-reports/*.xml' } } } stage('Deploy') { when { branch 'main' } steps { sh './deploy.sh staging' } } } post { failure { echo 'Build failed' } } }

How do you run a matrix build in GitHub Actions?

Show answer

jobs: test: runs-on: ${{ matrix.os }} strategy: fail-fast: false matrix: os: [ubuntu-latest, windows-latest] python: ['3.11', '3.12'] steps: - uses: actions/checkout@v4 - uses: actions/setup-python@v5 with: python-version: ${{ matrix.python }} - run: pip install -r requirements.txt - run: pytest This creates four parallel jobs; fail-fast false lets all finish so you see every failure.

Write a script that alerts when any disk partition is above 80 percent used.

Show answer

#!/bin/bash THRESHOLD=80 df -hP | awk 'NR>1 {gsub("%","",$5); print $5, $6}' | while read -r used mount; do if [ "$used" -ge "$THRESHOLD" ]; then echo "WARNING: $mount is ${used}% full on $(hostname)" fi done df -P keeps each entry on one line, awk strips the percent sign, and the loop compares each value with the threshold.

Which kubectl commands do you use most for debugging?

KubernetesEasy

Show answer

kubectl get pods -n shop -o wide kubectl describe pod api-7d9f -n shop kubectl logs api-7d9f -n shop -c api --previous kubectl logs -l app=api -f --tail=50 kubectl exec -it api-7d9f -- sh kubectl get events -n shop --sort-by=.lastTimestamp kubectl top pods -n shop kubectl port-forward svc/api 8080:80 kubectl get endpoints api describe and events usually explain scheduling and startup problems; logs explain application problems.

How do you squash your last three commits into one?

Git and Version ControlMedium

Show answer

git rebase -i HEAD~3 # in the editor, keep the first line as pick # and change the other two to squash (or s) pick a1b2c3 Add login API squash d4e5f6 Fix typo squash 789abc Add tests # alternative without the editor git reset --soft HEAD~3 git commit -m "Add login API with tests" If the branch was already pushed, update it with git push --force-with-lease.

Explain git reset --soft, --mixed and --hard.

Git and Version ControlMedium

Show answer

All three move the current branch pointer to another commit. --soft keeps your changes staged, useful for recombining commits. --mixed, the default, keeps changes in the working directory but unstaged. --hard discards changes in both staging and working directory, so uncommitted work is lost. Lost commits can usually still be found with git reflog for a while.

Write a bash script that checks whether a service is running and restarts it if not.

Show answer

#!/bin/bash set -u SERVICE="nginx" if ! systemctl is-active --quiet "$SERVICE"; then echo "$(date) $SERVICE down, restarting" >> /var/log/svc-check.log systemctl restart "$SERVICE" if ! systemctl is-active --quiet "$SERVICE"; then echo "$SERVICE failed to start" | mail -s "ALERT" ops@example.com fi fi Run it from cron every few minutes; a real setup would rely on systemd Restart= plus monitoring.

What is a webhook and how does it trigger a build?

Show answer

A webhook is an HTTP callback: when an event happens in the Git server, such as a push or pull request, it sends a POST request with event details to a configured URL. Jenkins or another CI tool receives it and starts the matching pipeline immediately. This is better than polling the repository every few minutes, which wastes resources and delays feedback.

Explain stdin, stdout, stderr and what 2>&1 means.

Show answer

Every process gets three file descriptors: 0 is stdin, 1 is stdout and 2 is stderr. > redirects stdout to a file, 2> redirects errors, and 2>&1 sends stderr to wherever stdout currently points. So command > out.log 2>&1 captures both normal output and errors in one file. Order matters: 2>&1 placed before > out.log would still print errors to the terminal.

How do you create a new branch, push it and set the upstream?

Show answer

git switch -c feature/payment-retry # make changes git add . git commit -m "Add retry for failed payments" git push -u origin feature/payment-retry After -u (set upstream), plain git push and git pull work on this branch without naming the remote. Then open a pull request against main.

How do you schedule a cron job to run every day at 2:30 AM?

Show answer

crontab -e # min hour day month weekday command 30 2 * * * /opt/scripts/backup.sh >> /var/log/backup.log 2>&1 crontab -l # list jobs Use absolute paths because cron runs with a minimal PATH and environment. Redirect output to a log, otherwise errors are mailed or lost. On systemd hosts, timers are an alternative with better logging.

The build works on your laptop but fails on the CI server. How do you debug it?

Show answer

The environments differ. Compare tool versions such as JDK, Node or Python, environment variables, and dependency versions, especially if there is no lock file. Check for files present locally but not committed, and for hard-coded paths. Reproduce by running the build inside the same Docker image the CI agent uses. Long term, build inside containers so local and CI match.

Why do you want to build a career in DevOps?

Show answer

I enjoy both writing code and understanding how systems run in production, and DevOps sits between the two. In my projects I set up a CI pipeline and Docker deployment and liked seeing a change go from commit to live in minutes. I want to keep learning cloud, Kubernetes and automation, and help teams release faster with fewer failures.

How do you create a release tag and push it?