HashiCorp Staff Software Engineer Interview Questions

1.Tell me about a time in code review where you pushed a teammate to significantly improve their design. What was wrong with the original approach, and how did you guide them to a better solution?

2.Describe the most complex internal tool you've built for your team. What problem was it solving, and how did you make sure it was actually usable rather than just technically impressive?

3.Tell me about a time you took an existing tool or workflow that was frustrating people and redesigned it to be dramatically simpler. What made the original version painful, and how did you approach the redesign?

4.Tell me about the last time you completely changed your mind on a significant technical decision. What was your original position, what new information changed it, and how did you communicate that shift to your team?

5.Describe a time you worked with an external contributor or open-source community member whose approach was very different from your team's. How did you navigate that collaboration?

6.Walk me through a system you designed where you had to plan specifically for failure modes. What could go wrong, how did you design for those failures, and what happened when you actually hit one of them?

7.Implement a function in Go that takes a slice of Nomad job allocations and returns the optimal node placement to minimize cross-AZ network traffic.

8.Write a small Go program that reads Terraform state and outputs a dependency graph in DOT format. Focus on handling circular dependencies gracefully.

9.A customer reports that their Terraform apply is taking 45 minutes for a plan with 1000 resources. The provider API has no rate limits. How would you investigate and fix this performance issue?

10.You need to add a new API endpoint to Vault that encrypts data using a customer's HSM. Walk me through your implementation approach, focusing on how you'd handle HSM failures.

11.You're implementing a new Consul feature that needs to replicate data across a cluster of 100+ nodes. Walk me through how you'd design the consensus mechanism to handle network partitions gracefully.

12.You're reviewing a pull request that adds a new gRPC service to Vault, but it doesn't follow any of our established patterns for authentication or rate limiting. How would you structure your code review feedback?

13.Design a state locking mechanism for Terraform that can handle 50,000 concurrent applies across different workspaces. How would you prevent state corruption while minimizing lock contention?

14.Design a configuration drift detection system for Terraform that can monitor 10,000 workspaces and alert when actual infrastructure diverges from declared state. How do you balance detection speed with API rate limits across different cloud providers?

15.You're building a secret rotation system for Vault that needs to coordinate with external systems like databases and AWS IAM. Design this to handle rotation failures gracefully without leaving secrets in an inconsistent state.

16.You're building a multi-cloud image builder for Packer that needs to coordinate builds across AWS, Azure, and GCP simultaneously. Design this to handle cloud provider outages and API rate limits while ensuring consistent artifacts.

17.Design Consul's gossip protocol to handle a cluster that needs to scale from 100 to 10,000 nodes while maintaining sub-second failure detection. How do you balance network overhead with detection speed?

18.Design a job scheduling system for Nomad that can handle 100,000 jobs across 5,000 nodes, where jobs have complex constraints like 'schedule near my database but not on the same rack.' How do you make scheduling decisions fast enough to handle this scale?

19.Tell me about a junior engineer on your team whose growth you accelerated. What specific actions did you take?

20.Tell me about a time you had to deliver bad news about a technical decision to a customer or stakeholder. How did you handle that conversation?

21.Tell me about a time you had to influence a principal engineer or architect who disagreed with your technical approach. How did you navigate that dynamic?

22.Walk me through a time when you had to advocate for taking on significant technical debt to ship something faster. How did you make that case?

23.Describe a time you had to get multiple teams aligned on a shared infrastructure decision that would affect all of them. What was your approach?

24.Describe a technical standard or practice you established across your organization. How did you get teams to actually adopt it?

25.Terraform Cloud serves over 100,000 organizations. If we wanted to estimate how many API calls we handle per day, walk me through your approach and assumptions.

26.Our Consul Connect adoption is lower than expected. Given that service mesh provides clear security benefits, why might teams be avoiding it and how would you validate your hypotheses?

27.A Vault customer reports that secret retrieval latency spiked from 50ms to 500ms, but our monitoring shows backend storage is healthy. How would you diagnose this?

28.We're considering adding a new feature to Terraform that requires storing additional metadata in state files. How would you estimate the storage impact across our entire customer base?

29.Nomad needs to schedule 10,000 batch jobs in the next hour, but our cluster only has capacity for 3,000. How would you design a fair scheduling algorithm that maximizes cluster utilization while respecting user priorities?

30.We want to understand if Terraform module downloads correlate with eventual Terraform Cloud adoption. Design an analysis approach that respects user privacy while giving us actionable insights.