Metrics Monitoring System - Tradeoffs and Alternatives
Architecture Tradeoffs
Pull vs Push Model
Pull (Prometheus-style)
- Pros: Service discovery, scrape control, simpler targets
- Cons: Firewall issues, short-lived jobs difficult
- Use when: Long-running services, control over scraping
Push (StatsD-style)
- Pros: Works behind firewalls, good for short jobs
- Cons: No service discovery, backpressure issues
- Use when: Batch jobs, serverless, restricted networks
Decision: Support both with push gateway
Storage Tradeoffs
Prometheus TSDB
- Pros: Simple, proven, good for single node
- Cons: Limited horizontal scaling, no HA
- Best for: Small to medium deployments
VictoriaMetrics
- Pros: Better compression, horizontal scaling, PromQL compatible
- Cons: Less mature, smaller community
- Best for: Large scale, cost-sensitive
InfluxDB
- Pros: Mature, good tooling, clustering
- Cons: Different query language, higher cost
- Best for: Multi-tenant, need SQL-like queries
Decision: VictoriaMetrics for scale and cost
Alert Manager Tradeoffs
Embedded Alerting
- Pros: Simpler architecture, lower latency
- Cons: Tightly coupled, harder to scale
- Use when: Small scale, simple requirements
Separate Alert Manager
- Pros: Independent scaling, deduplication, routing
- Cons: More complex, additional component
- Use when: Large scale, complex routing
Decision: Separate for flexibility
Query Language Tradeoffs
PromQL
- Pros: Purpose-built for metrics, powerful, standard
- Cons: Learning curve, limited to time-series
- Best for: Metrics-focused monitoring
SQL
- Pros: Familiar, flexible, tooling support
- Cons: Not optimized for time-series
- Best for: General-purpose queries
Decision: PromQL for compatibility
Consistency Tradeoffs
Strong Consistency
- Pros: Always accurate, no stale data
- Cons: Higher latency, lower availability
- Use for: Billing metrics, SLA tracking
Eventual Consistency
- Pros: Lower latency, higher availability
- Cons: Temporary inconsistencies
- Use for: Monitoring dashboards, alerts
Decision: Eventual for most, strong for critical
Alternative Approaches
Managed Services
Datadog, New Relic
- Pros: No operations, rich features, support
- Cons: High cost, vendor lock-in, data privacy
- Best for: Small teams, want turnkey solution
Self-hosted
- Pros: Full control, lower cost at scale, data ownership
- Cons: Operational burden, need expertise
- Best for: Large scale, specific requirements
Sampling vs Full Collection
Full Collection
- Pros: Complete data, accurate
- Cons: Higher cost, more storage
- Use when: Critical metrics, low volume
Sampling
- Pros: Lower cost, reduced load
- Cons: May miss issues, statistical only
- Use when: High volume, trends sufficient
Decision: Full for critical, sampling for high-volume
These tradeoffs guide architectural decisions based on scale, requirements, and constraints.