What is Site Reliability Engineering?
Site Reliability Engineering (SRE) is a discipline that applies software engineering principles to infrastructure and operations. Coined by Google in 2003, SRE has become the standard approach for running reliable production systems.
Core SRE Principles
1. Service Level Objectives (SLOs)
Define clear reliability targets for your services:
- SLI (Service Level Indicator) — A measurable metric (latency, error rate, throughput)
- SLO (Service Level Objective) — The target value for an SLI (99.9% availability)
- SLA (Service Level Agreement) — The contractual commitment to customers
Start with the most critical user journeys and work outward.
2. Error Budgets
An error budget is the acceptable amount of unreliability. If your SLO is 99.9%, your error budget is 0.1% (about 43 minutes per month).
When the error budget is consumed:
- Freeze feature releases
- Focus on reliability improvements
- Conduct postmortems for incidents that burned budget
3. Toil Reduction
Toil is repetitive, manual, automatable work that scales linearly with service growth. SRE teams should spend no more than 50% of their time on toil.
Automate:
- Incident response runbooks
- Scaling operations
- Certificate rotations
- Configuration changes
4. Blameless Postmortems
After every significant incident, conduct a blameless postmortem:
- Focus on systemic causes, not individual blame
- Identify what went wrong and what went right
- Create action items with owners and deadlines
- Share learnings across the organization
5. Monitoring and Alerting
Effective monitoring follows the USE and RED methods:
- USE: Utilization, Saturation, Errors (for infrastructure)
- RED: Rate, Errors, Duration (for services)
Alert on symptoms (user impact), not causes (CPU usage).
SRE Tools and Practices
- Incident management: PagerDuty, OpsGenie, SRExpert
- Monitoring: Prometheus, Grafana, SRExpert
- Chaos engineering: Chaos Monkey, Litmus
- Runbook automation: Ansible, SRExpert AI Assistant
How SRExpert Supports SRE Teams
SRExpert was built for SRE teams managing Kubernetes infrastructure. Our platform provides SLO tracking, smart alerting, AI-powered troubleshooting, and automated compliance — everything SRE teams need in one place.