Service-level indicator

As explained in Effective Platform Engineering

A service-level indicator is a quantitative measurement of a service’s reliability or performance from the perspective of its users.

A service-level indicator (SLI) is a quantitative metric of a service’s reliability or performance from the user’s perspective. Typical SLIs include response latency, throughput, error rate, and availability. An SLI measures current behavior; a service-level objective (SLO) sets a target for that behavior, while a service-level agreement (SLA) formalizes customer commitments and consequences. section 5.4 section 10.4.1

Use SLIs to connect operational measurement with reliability work:

• Choose measures that reflect customer experience and business priorities rather than collecting metrics without a decision context. section 5.4 section 10.4.2
• Automate collection and make the measurements visible so platform teams can track service health and investigate problems. section 5.4 section 5.4.1
• Pair each important SLI with an SLO, then use error budgets to balance change velocity against reliability. section 10.4.1 section 10.8

Platform API latency

If a custom platform API consistently responds in 200 milliseconds, response time is an SLI. An associated SLO might require responses within 200 milliseconds for 99.9% of requests. A breach prompts investigation and remediation; an enterprise SLA may additionally specify compensation. section 5.4

Figure 5.11 SLIs inform SLOs that can be used to notify and publish SLAs.

The relationship diagram shows how measured SLIs inform SLOs, which can support notifications and published SLAs. section 5.4

How Effective Platform Engineering covers it

How deep it goes

Defines SLIs and relates them to SLOs and SLAs, then applies them to dashboards, monitoring, and reliability practices.

Examples

Uses API response time, latency, throughput, error rates, payment processing, dashboards, and Prometheus data as examples.

What it assumes

Assumes familiarity with service performance and reliability, while establishing the SLI, SLO, and SLA distinctions explicitly.

What you can do after

Apply it via Prometheus and Grafana to define, visualize, monitor, and diagnose reliability objectives.

How it connects

Connects service-level objectives, service-level agreements, error budgets, observability, Prometheus, and Grafana.

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Also explained in

• 

  liveBookmanning.com
  Cloud Observability in ActionA service level indicator is a quantitative measurement of a service aspect relevant to evaluating a service level objective.
• 

  liveBookmanning.com
  Automating API DeliveryA service level indicator is a quantitative measure of an aspect of a service's health or performance.

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Related concepts

• service-level objectiveconfigured by · A service-level objective is a target value or range for a measurable service-level indicator over a specified period.
• performancekind of · Performance is the measurable effectiveness or operational behavior of a system under specified conditions, assessed through relevant qualities such as task results, speed, responsiveness, throughput, or resource use.
• metrickind of · A metric is a quantitative measure used to characterize or assess a property, condition, behavior, performance, or outcome.
• contractmeasures · An API contract is a specification of the operations, data, and behavioral expectations that govern interactions between software components.
• meanmeasures · A mean is a measure of central tendency, calculated as the arithmetic average of values or, for a random variable, as the probability-weighted average of its possible values.
• uptimemeasures · Uptime is the duration or proportion of a specified period during which a system or service is operational and available to provide its intended function.

This explainer was generated by Manning's knowledge graph from the text of Effective Platform Engineering. The section links point to the parts of the book it draws on.