What do you look for when hiring SREs, and how do you design an interview process that identifies the right candidates?

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Accepted Answer

Hiring SREs requires evaluating a unique combination of skills that spans software engineering, systems knowledge, and operational judgment. The interview process must assess all three dimensions while avoiding the common pitfall of hiring either pure developers who lack operational intuition or pure operations engineers who lack engineering discipline.

The core competencies I evaluate are software engineering ability, systems and infrastructure knowledge, operational judgment and incident response, and collaboration and communication. Each competency has specific signals I look for and dedicated interview segments designed to assess them.

Software engineering assessment goes beyond algorithm puzzles. I ask candidates to write production-quality code that handles errors, logs appropriately, and is testable. A typical problem might be implementing a rate limiter, a health check aggregator, or a simple monitoring agent. I evaluate code quality, error handling, testability, and the candidate's approach to edge cases. SREs write code that runs in production, so I prioritize practical engineering skills over algorithmic complexity.

Systems knowledge assessment evaluates understanding of how computing infrastructure works. I present scenarios that require reasoning about networking, storage, operating systems, and distributed systems. For example, how would you debug a service that intermittently responds slowly, or what happens when a server's disk fills up and how do you prevent it? I look for candidates who can reason from first principles rather than relying on memorized answers, because production systems present novel problems that cannot be looked up.

Operational judgment assessment is the most SRE-specific part of the interview. I present realistic incident scenarios and ask candidates to walk through their response. A good scenario might be that monitoring shows a gradual increase in error rates for a critical service, alerts fire, and the candidate must describe their investigation and mitigation approach. I evaluate whether they prioritize mitigation over root cause investigation, whether they communicate effectively about status and impact, and whether they consider cascading effects and blast radius.

Troubleshooting exercises test the ability to diagnose unfamiliar systems. I present a system with a defined architecture and symptoms, such as high CPU on a web server with increasing response times, and ask the candidate to work through diagnosis. The specific answer matters less than the methodology: does the candidate form hypotheses, gather data systematically, and adjust their approach based on findings?

Collaboration assessment evaluates how candidates work with others during incidents and projects. SREs must communicate clearly under pressure, teach others, and navigate organizational dynamics. I include a collaborative exercise where the candidate works with the interviewer on a problem, and I assess their communication style, willingness to ask questions, and ability to explain their reasoning.

Cultural fit for SRE specifically means evaluating alignment with SRE values: curiosity about how systems fail, a drive to automate repetitive work, comfort with ambiguity, and a blameless approach to failure. I ask about past experiences with incidents, automation projects, and cross-team collaboration to assess these values.

For senior SRE candidates, I add an architecture and strategy assessment. I present an organizational scenario, for example a company experiencing rapid growth with increasing reliability problems, and ask the candidate to describe how they would design an SRE function, establish practices, and prioritize investments. This assesses strategic thinking and organizational awareness alongside technical depth.

The interview panel should include SREs, software engineers, and engineering managers to evaluate candidates from multiple perspectives. A candidate who impresses SREs with systems knowledge should also demonstrate sufficient engineering skill to satisfy software engineers, and sufficient communication ability to satisfy managers. This multi-perspective evaluation prevents hiring blind spots.

I explicitly assess for growth potential alongside current capability. A candidate who demonstrates strong learning ability, intellectual curiosity, and a systematic approach to unfamiliar problems may outperform a candidate with more experience but less adaptability, especially in the rapidly evolving SRE field.