HashiCorp Software Engineer Interview Questions

1.Walk me through a time you gave code review feedback that significantly changed how a teammate approached their design. What was the original approach, what did you suggest, and how did the conversation go?

2.Describe a time you inherited a complex internal tool or process that was painful for your team to use. How did you go about understanding the pain points and what did you do to improve it?

3.Tell me about a time you took an existing tool or system your team was using and made it dramatically simpler for users. What was broken about the original workflow, and how did you redesign it?

4.Tell me about a system you built that had to handle failures gracefully. What failure modes did you plan for, and how did you test that your system actually worked when things went wrong?

5.Describe a time you collaborated with someone outside your company - an open source contributor, external partner, or community member. How did you navigate the collaboration, and what was the outcome?

6.Walk me through a significant technical decision you were convinced was right, but then changed your mind about. What new information changed your perspective, and how did you handle the pivot?

7.You're debugging an issue where Terraform plan generation is taking 45 minutes for a large configuration that used to complete in 5 minutes. Where do you start investigating?

8.Design a health check system for a microservice that needs to report healthy only when it can successfully connect to its database, message queue, and external API dependency. Code the health check endpoint.

9.You need to implement a secrets rotation system that can update database credentials across hundreds of applications without downtime. How would you design this?

10.Let's say you're building a CLI tool in Go that needs to authenticate with multiple cloud providers. Code up a plugin architecture that allows adding new providers without changing the core CLI code.

11.You're implementing leader election for a distributed service using Raft consensus. Walk me through how you'd handle the case where the current leader becomes partitioned but hasn't crashed yet.

12.You're implementing a feature where Terraform needs to wait for a cloud resource to become ready, but the cloud provider's API doesn't support webhooks. How would you implement the polling logic?

13.Design a distributed state locking system for Terraform that prevents two operators from modifying the same infrastructure simultaneously. The system needs to handle network partitions and operator crashes gracefully.

14.Design an image building pipeline for Packer that can create machine images for 20 different cloud providers simultaneously while ensuring consistent configuration and minimal build time variance.

15.You're building a secrets syncing service for Vault that pushes database credentials to hundreds of applications across multiple clouds. Design the system to handle credential rotation without causing application downtime.

16.Design a resource dependency graph system for Terraform that can detect circular dependencies and optimize the order of resource creation across 50,000 resources. The system needs to handle provider failures gracefully.

17.Design the gossip protocol layer for Consul that allows nodes to efficiently share service health information across a cluster of 10,000 nodes. How do you prevent network flooding while ensuring rapid failure detection?

18.Design a multi-region job scheduling system for Nomad that can handle 100,000 concurrent jobs while ensuring fair resource allocation across different teams and priorities. The system must gracefully handle datacenter failures.

19.Tell me about a time you had to convince a teammate to simplify their approach when they wanted to build something more complex or feature-rich. How did you handle that conversation?

20.Describe a situation where you had to admit you didn't know something technical in front of your team or in a design discussion. How did you handle it?

21.Walk me through a time you wrote a design document or technical RFC that changed how your team approached a problem. What was your process for building consensus around the proposal?

22.Tell me about a time you had to step up and coordinate work across multiple engineers or teams when there wasn't a clear owner. What was the outcome?

23.Describe a time you had to give difficult feedback to a peer about their code or technical approach. How did you deliver it, and what was the result?

24.Tell me about a time you disagreed with a technical decision your manager or a senior engineer was pushing for. How did you navigate that situation?

25.Estimate how many Terraform state files are actively managed across all of HashiCorp's paying customers. Walk me through your reasoning and assumptions.

26.You notice that Vault secret retrieval latency has increased 20% over the past month, but throughput hasn't changed. No new features shipped. How would you investigate this?

27.HashiCorp wants to estimate the cost impact of adding real-time change notifications to Terraform Cloud. Each notification costs about 2 cents to send. How would you model the financial impact?

28.Design a capacity planning model for Consul clusters that helps customers decide when to add nodes. What factors would you include and how would you weight them?

29.You're tasked with estimating how much engineering effort it would take to add WASM plugin support to Nomad. The CEO wants a rough timeline for planning purposes. How do you approach this?

30.HashiCorp's open source download numbers dropped 15% month-over-month, but paid customer usage is steady. The community team thinks it's a website issue, but engineering thinks it's a product problem. How would you figure out the root cause?