Question 1

How do you approach setting up a CI/CD pipeline for a new service?

Accepted Answer

I start with automated build and test stages that run on every commit, then add a staging deploy gated on test pass, and a manual or automated production promotion depending on the team's risk tolerance. I make sure rollback is as simple as the deploy itself, usually by keeping the previous artifact ready to redeploy.

Question 2

Walk me through how you'd debug a production incident where a service is returning 500 errors.

Accepted Answer

I check the service's recent deploy history first, since a recent change is the most common cause, then pull logs and metrics like error rate and latency from our monitoring stack to isolate the failing component. If it's a recent deploy I roll back immediately to restore service before doing root cause analysis.

Question 3

How do you manage secrets and credentials across your infrastructure?

Accepted Answer

I use a secrets manager like Vault or AWS Secrets Manager rather than hardcoding or storing them in environment files in the repo, and I rotate credentials on a schedule, especially for anything with broad access. Secrets in plaintext config files are one of the most common security findings I look for in a review.

Question 4

Describe your approach to infrastructure as code and why you use it.

Accepted Answer

I define infrastructure in Terraform or similar so changes go through code review and version control rather than manual console changes, which prevents drift and makes the environment reproducible. I always run a plan before apply and review the diff carefully, since a wrong apply can take down production.

Question 5

How do you approach setting up monitoring and alerting for a new service?

Accepted Answer

I instrument the four golden signals, latency, traffic, errors, and saturation, and set alert thresholds based on what actually indicates user impact rather than arbitrary numbers. I tune alerts over the first few weeks to reduce noise, since an ignored alert from too many false positives is worse than no alert.

Question 6

Walk me through how you'd handle a database migration with zero downtime requirements.

Accepted Answer

I use a backward-compatible schema change approach, like adding new columns before removing old ones, and deploy application code that works with both old and new schema during the transition. I test the migration on a staging environment with production-like data volume before running it live.

Question 7

How do you decide between containerizing a service versus running it on a VM?

Accepted Answer

I consider the service's scaling needs, dependency isolation requirements, and team familiarity, generally leaning toward containers for stateless services that need to scale horizontally. For something stateful with unusual resource requirements, a VM or managed service might still be simpler and more reliable.

Question 8

Describe how you approach capacity planning for an application expecting a traffic spike, like a product launch.

Accepted Answer

I load test against expected peak traffic beforehand, usually at 1.5 to 2 times the projected number for margin, and set up autoscaling policies with a fast enough scale-up trigger to handle a sudden spike. I also make sure the database, not just the app servers, can handle the increased load since that's often the actual bottleneck.

Question 9

How do you handle a situation where a teammate wants to skip code review to ship a hotfix faster?

Accepted Answer

For a true production emergency I'll do an expedited review, focusing just on the specific change rather than blocking on style nits, but I don't skip it entirely since a rushed unreviewed fix has caused outages before. A five-minute review is rarely the actual bottleneck in an incident.

Question 10

What's your approach to reducing cloud infrastructure costs without hurting reliability?

Accepted Answer

I start by identifying underutilized resources through actual usage metrics, like rightsizing instances running at 10% CPU, before cutting anything that affects redundancy or headroom. I also check for orphaned resources like unattached volumes or old snapshots, which are often pure waste with zero tradeoff.

DevOps Engineer interview questions and sample answers

Job-specific questions

1. How do you approach setting up a CI/CD pipeline for a new service?

2. Walk me through how you'd debug a production incident where a service is returning 500 errors.

3. How do you manage secrets and credentials across your infrastructure?

4. Describe your approach to infrastructure as code and why you use it.

5. How do you approach setting up monitoring and alerting for a new service?

6. Walk me through how you'd handle a database migration with zero downtime requirements.

7. How do you decide between containerizing a service versus running it on a VM?

8. Describe how you approach capacity planning for an application expecting a traffic spike, like a product launch.

9. How do you handle a situation where a teammate wants to skip code review to ship a hotfix faster?

10. What's your approach to reducing cloud infrastructure costs without hurting reliability?

Behavioral questions

11. Tell me about a result you are proud of.

12. Describe a time you improved how something was done.

13. Tell me about a time you had to deliver under pressure.

14. Give an example of working with a difficult colleague or customer.

15. What is something you learned from a mistake?

Before the interview

Interview questions for related jobs