prometheus-metrics-specialist

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Instrument services with Prometheus metrics and write PromQL queries. Guides HuleEdu naming conventions, metrics middleware setup, and business vs operational metrics. Integrates with Context7 for latest Prometheus documentation.

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When & Why to Use This Skill

The Prometheus Metrics Specialist skill is a comprehensive technical guide designed to help developers instrument services with Prometheus metrics and master PromQL. It provides standardized patterns for HuleEdu naming conventions, middleware setup, and the implementation of both operational and business-level metrics, ensuring robust system observability and data-driven insights.

Use Cases

  • Instrumenting HTTP endpoints, Kafka event processing, and database queries with appropriate Prometheus metric types like Counters and Histograms.
  • Writing complex PromQL queries to calculate real-time error rates, P95 latencies, and troubleshooting system performance issues on dashboards.
  • Implementing standardized naming conventions across microservices to ensure consistency between service-specific and cross-service business metrics.
  • Monitoring specialized AI workloads, such as tracking LLM API call tokens and batch processing durations for cost and performance analysis.
  • Designing efficient label structures and histogram buckets to optimize metric cardinality and improve monitoring accuracy.
nameprometheus-metrics-specialist
descriptionInstrument services with Prometheus metrics and write PromQL queries. Guides HuleEdu naming conventions, metrics middleware setup, and business vs operational metrics. Integrates with Context7 for latest Prometheus documentation.

Prometheus Metrics Specialist

Compact skill for instrumenting HuleEdu services with Prometheus metrics and querying them with PromQL.

When to Use

Activate when the user:

  • Needs to add metrics instrumentation to a service
  • Wants to write PromQL queries for dashboards or alerts
  • Asks about metrics naming conventions
  • Needs help with metrics middleware setup
  • Wants to understand business vs operational metrics
  • Mentions Prometheus, PromQL, metrics, instrumentation, or monitoring
  • Needs to expose /metrics endpoint

I Need To...

Get Started (First Time)

  1. Learn Prometheus basics → fundamentals.md - Counter, Histogram, Gauge concepts
  2. Set up HuleEdu service → huleedu-patterns.md - metrics.py module, /metrics endpoint
  3. Pick an example → See "Add Metrics to Service" below

Add Metrics to Service

I need to instrument... Read this file
HTTP endpoints examples/http-and-kafka.md
Kafka event processing examples/http-and-kafka.md
LLM API calls examples/llm-and-batch.md
Batch processing examples/llm-and-batch.md
Database queries examples/database-and-business.md
Business logic examples/database-and-business.md

Choose Naming Pattern

→ huleedu-patterns.md § Naming Patterns

Write PromQL Queries

I need to... Read this section
Learn PromQL syntax promql-guide.md § Basics
Calculate error rate promql-guide.md § Error Rates
Get P95 latency promql-guide.md § Percentiles
Troubleshoot issues promql-guide.md § Troubleshooting

Reference

What I need to know Where to find it
Metric types (Counter/Histogram/Gauge) fundamentals.md § Metric Types
Label design principles fundamentals.md § Labels
Histogram bucket design fundamentals.md § Buckets
HuleEdu architecture huleedu-patterns.md § Architecture

Quick Metric Type Cheatsheet

# Counter: Events that only increase (resets to 0 on restart)
operations_total = Counter("spell_checker_operations_total", "desc", ["status"])
operations_total.labels(status="success").inc()

# Histogram: Distributions (latency, sizes, scores)
duration_seconds = Histogram("spell_checker_duration_seconds", "desc")
duration_seconds.observe(0.23)  # 230ms

# Gauge: Point-in-time values that go up/down
active_connections = Gauge("spell_checker_active_connections", "desc")
active_connections.set(15)
active_connections.inc()  # 16

HuleEdu Naming Cheatsheet

# Pattern 1: Service-Prefixed (most common, operational metrics)
spell_checker_operations_total
spell_checker_http_request_duration_seconds

# Pattern 2: Business Metrics (cross-service, business logic)
huleedu_llm_prompt_tokens_total
huleedu_spellcheck_corrections_made

# Pattern 3: Legacy (being phased out)
request_count

Decision: Service-specific metric? → Pattern 1. Cross-service business metric? → Pattern 2.

Core Capabilities

  • Naming Conventions: 3 patterns (service-prefixed, business, legacy)
  • Instrumentation: Counter, Histogram, Gauge, Summary usage
  • Middleware Setup: Standard HTTP metrics middleware
  • Service-Specific Metrics: Business logic patterns
  • PromQL Queries: Troubleshooting and dashboard queries
  • Scrape Configuration: Prometheus targets and discovery
  • Best Practices: Metric types, cardinality, aggregation
  • Context7 Integration: Latest Prometheus/PromQL docs

Documentation Structure