Introduction
The role of a Site Reliability Engineer (SRE) often gets reduced to “the person who gets paged at 2 AM.” But in practice, an SRE is much more than an incident responder. They are engineers dedicated to the reliability, scalability, and performance of systems—bridging the gap between development and operations. This article breaks down what SREs actually do, day to day and across the lifecycle of software.
Availability as a Product
SREs treat reliability as a feature. Just like you’d scope out UI changes, SREs design and measure availability targets like SLAs (Service Level Agreements), SLOs (Service Level Objectives), and SLIs (Service Level Indicators). They’re responsible for helping teams hit those targets without overburdening developers or compromising the pace of innovation.
Key activities:
- Defining SLAs/SLOs with product teams
- Monitoring service health and error budgets
- Tracking uptime and latency metrics across services
Automated Operations
SREs believe that “toil”—manual, repetitive tasks—should be eliminated wherever possible. This leads to an automation-first culture, where scripts, bots, and runbooks replace ad hoc fixes.
Key activities:
- Automating deployment pipelines
- Writing self-healing scripts and watchdogs
- Maintaining Infrastructure-as-Code (IaC)
Incident Response and Postmortems
Yes, SREs do respond to incidents—but their job doesn’t stop there. Their real focus is improving response processes and preventing repeat issues. That includes structuring on-call rotations, defining escalation policies, and conducting in-depth post-incident reviews.
Key activities:
- Participating in or leading incident response
- Managing alerting thresholds and on-call schedules
- Writing and facilitating blameless postmortems
- Identifying systemic issues and feeding them back to dev teams
Performance and Scalability Engineering
As services grow, performance bottlenecks and scaling issues emerge. SREs run load tests, optimize latency, and work on architectural improvements to ensure systems can handle real-world demands.
Key activities:
- Running performance benchmarks and profiling
- Caching strategies, database tuning, and horizontal scaling
- Supporting multi-region deployments and failover mechanisms
Tooling and Developer Enablement
SREs build tools that make it easier for developers to ship and operate reliable software. This often includes observability dashboards, CLI tools, internal libraries, or deployment abstractions.
Key activities:
- Building internal tools for deploys, rollbacks, and diagnostics
- Creating dashboards and alerts via tools like Prometheus, Datadog, or Grafana
- Contributing to platform teams and shared infrastructure
Security, Compliance, and Chaos Engineering
Many SREs also overlap with security and compliance efforts, especially in regulated industries. They may run tabletop exercises, simulate failures (chaos engineering), and ensure the systems can degrade gracefully.
Key activities:
- Running chaos experiments and fault injection drills
- Ensuring compliance with audit logs and data retention policies
- Enforcing access controls and secure system boundaries
Conclusion: SRE as a Systems Thinker
The best SREs aren’t just “fixers.” They’re systems thinkers who anticipate failure, design for resilience, and build platforms that scale with confidence. Whether working on alerting systems or availability SLAs, their goal remains the same: keeping software reliable without sacrificing developer velocity.