GitLab Senior Software Engineer Interview Questions

1.Tell me about a time when you created or improved documentation that your team relied on. What was missing, and how did you make sure it stayed useful?

2.Tell me about a time you had to convince your team to stick with an existing solution instead of adopting something new they were excited about. What was your argument?

3.Describe a situation where you chose a well-established technology or approach over something newer and more exciting. What drove that decision?

4.Walk me through a time you stepped outside your assigned area to fix or improve something that was affecting your work. How did you approach that situation?

5.Tell me about a time when someone from outside your team made changes or contributions to your area of ownership. How did you handle that, and what was the outcome?

6.Describe a complex technical decision you had to document for future teams. What made it complex, and how did you ensure your documentation would be useful months later?

7.Our GitLab CI pipeline for the main application takes 45 minutes to run the full test suite, and developers are complaining about slow feedback. How would you approach reducing this time while maintaining test coverage?

8.You're reviewing a merge request that adds a new API endpoint to handle repository file uploads. The implementation works but creates a 500-line controller method. How do you handle this review?

9.A critical security vulnerability was discovered in one of our Ruby gems that affects the main GitLab Rails application. You need to coordinate the fix across multiple teams. Walk me through your approach.

10.You're building a feature that needs to aggregate data from multiple GitLab projects for a dashboard view. The naive approach creates N+1 query problems when users have hundreds of projects. Design a solution that scales.

11.GitLab.com handles millions of Git operations daily across thousands of repositories. You notice that large repository clones are causing memory spikes that affect other operations. How would you investigate and address this?

12.We want to add real-time collaboration features to GitLab's Web IDE, similar to Google Docs. Multiple developers should see each other's changes as they type. What technical challenges would you expect, and how would you approach building this?

13.Our GitLab instance needs to support repository mirroring where changes to external Git repositories automatically sync to GitLab projects. This includes handling authentication, conflict resolution, and keeping mirrors up-to-date. What's your design?

14.We want to build a feature that automatically suggests code reviewers for merge requests based on file changes, team expertise, and workload. It needs to work across thousands of projects with different team structures. Walk me through your approach.

15.We want to add a feature where GitLab automatically creates merge requests when security vulnerabilities are detected in dependencies. This needs to work across thousands of projects with different languages and package managers. What's your approach?

16.GitLab's CI/CD system processes millions of pipeline jobs daily. We need to add support for pipeline-level secrets that can be shared across jobs but shouldn't be logged or exposed in artifacts. How do you design the secrets management?

17.GitLab Duo, our AI-powered development assistant, needs to provide code suggestions to millions of developers in real-time. Each suggestion request involves calling multiple AI models and processing context from the user's current file. How would you design this system to handle 100,000 requests per minute?

18.GitLab.com serves Git clone and push operations for millions of repositories. We're seeing performance issues during peak hours when many users are pushing large files simultaneously. How would you design a solution to optimize Git operations at this scale?

19.Tell me about a time you had to drive a technical decision without consensus from all stakeholders. How did you move forward and what was the outcome?

20.Describe a situation where you mentored someone remotely across time zones. What challenges did you face and how did you adapt your approach?

21.Tell me about a time you had to influence an engineering manager or director to change their team's technical approach. What was your strategy and how did it go?

22.Walk me through a time you had to coordinate a technical initiative across multiple teams when those teams had conflicting priorities. How did you align everyone?

23.Describe a situation where you inherited a critical system or codebase that had poor documentation and no clear ownership. How did you establish accountability and improve the situation?

24.Tell me about a time you had to convince your team to kill or significantly reduce scope on a project they were excited about. How did you approach that conversation and what was the result?

25.GitLab.com processes 50 million merge requests per year. We're considering adding a feature that runs automated accessibility scans on every MR that touches frontend code. Estimate the computational cost and walk me through your assumptions.

26.A PM reports that GitLab Duo code suggestions acceptance rate dropped from 35% to 28% over two weeks, but our telemetry shows suggestion quality scores are stable. How do you investigate this discrepancy?

27.We want to estimate the revenue impact if we reduced GitLab CI/CD job queue times by 30%. Walk me through how you'd calculate this and what data you'd need.

28.GitLab's handbook has over 5,000 pages and gets 200+ edits daily. We're seeing complaints that people can't find information quickly. Design a solution to improve discoverability without breaking our handbook-first culture.

29.Estimate how many additional GitLab Premium subscriptions we could gain if we reduced security scan false positive rates from 15% to 5%. Consider developer time savings and competitive positioning.

30.We're considering making all private repositories on GitLab.com count toward storage limits, currently only LFS and artifacts do. Estimate the customer impact and revenue implications of this change.