HashiCorp DevOps / SRE Interview Questions

1.Describe a time when you reviewed someone else's code or design and identified a significant issue that they missed. How did you communicate the problem and what was the outcome?

2.Tell me about a time you had to simplify or completely rebuild a deployment process or operational runbook because it was too complex for your team to execute reliably.

3.Tell me about a time you took an internal tool or operational workflow that was painful to use and completely redesigned it. What made it painful originally, and how did your redesign change the daily experience for your users?

4.Walk me through a time when you were convinced a particular technical approach was right, but then changed your mind based on new information. What was your original position and what caused you to update it?

5.Describe a time you worked with an external contributor or open source community to solve a problem with your infrastructure or tooling. What was challenging about that collaboration and how did you navigate it?

6.Tell me about a system you designed or significantly modified where you had to plan for specific failure scenarios. What failures did you anticipate and how did you design the system to handle them gracefully?

7.A customer reports that their Nomad cluster is scheduling jobs unevenly, with some nodes sitting idle while others are overloaded. Walk me through your debugging approach.

8.You're tasked with implementing health checks for a service mesh where services need to distinguish between startup delays, temporary failures, and permanent failures. How would you design this?

9.Walk me through how you'd design monitoring and alerting for a Terraform Cloud workspace that provisions infrastructure across AWS, Azure, and GCP simultaneously.

10.You need to implement secret rotation for database credentials used by 200+ microservices, where downtime isn't acceptable. How would you design this using Vault's dynamic secrets?

11.You're on-call and get paged that Consul's gossip protocol is experiencing severe network partitions across multiple availability zones. How would you investigate and what steps would you take to restore cluster health?

12.Design a deployment strategy for rolling out a critical security patch to Vault servers serving 50,000 QPS with strict SLA requirements.

13.Design an image building pipeline for Packer that creates machine images across AWS, Azure, and GCP simultaneously while ensuring consistency and handling cloud-specific failures gracefully.

14.You're building a metrics aggregation system for HashiCorp Cloud Platform that ingests telemetry from Terraform, Vault, and Consul. How do you design it to handle 1M metrics per second with sub-second query latency?

15.You need to design a certificate management system for Vault PKI that automatically rotates short-lived certs for 5,000 microservices. How do you handle renewal, distribution, and graceful failures?

16.Walk me through how you'd design a job scheduler for Nomad that can efficiently pack 10,000 containers across 500 heterogeneous nodes while respecting resource constraints and affinity rules.

17.Design the state storage and locking mechanism for Terraform Cloud to handle 10,000 concurrent plan/apply operations across different workspaces. How do you prevent state corruption and race conditions?

18.Design a gossip-based health checking system for Consul that can detect and propagate node failures across a 1,000-node cluster within 30 seconds. How do you balance detection speed with network overhead?

19.Tell me about a time when you had to convince someone significantly more senior than you that their technical decision was wrong. How did you approach that conversation?

20.Describe a time when you wrote documentation or created a runbook that significantly changed how your team operated. What was broken about the old way?

21.Walk me through a time when you had to mentor or teach someone on a distributed systems concept they were struggling with. How did you approach making it click for them?

22.Tell me about a time you had to coordinate a complex infrastructure change across multiple teams that had different priorities and timelines. How did you get alignment?

23.Describe a situation where you had to push back on a product or engineering decision because it would create operational complexity for your team. What was your argument and how did it resolve?

24.Tell me about a time when you had to lead an incident response or outage where the root cause wasn't immediately obvious and multiple teams were involved. How did you coordinate the investigation?

25.Estimate how many Consul clusters HashiCorp's enterprise customers are running in production globally, and what that tells us about our infrastructure monitoring needs.

26.You notice that 15% of Terraform plan operations are failing due to provider timeouts, but only during certain hours. How would you approach diagnosing this pattern and what solutions would you consider?

27.Our Terraform Cloud platform serves 100,000 daily active users running infrastructure plans. If we wanted to reduce our compute costs by 20% while maintaining current performance, how would you estimate the impact and approach this optimization?

28.Your monitoring shows that Nomad job placement is taking 50% longer than usual, but cluster resources appear available. How would you systematically debug this performance degradation?

29.Vault's usage has grown 300% year-over-year, but our support ticket volume grew 500% in the same period. Walk me through how you'd investigate why support tickets are growing faster than usage and what operational changes you'd recommend.

30.If HashiCorp wanted to add real-time collaboration features to Terraform Cloud, similar to Google Docs, estimate the additional infrastructure costs and technical complexity this would introduce.