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Hosted Prometheus vs. Self-Managed: A Neutral Guide to Costs, Control, and Trade-offs

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Hosted Prometheus: Managed Simplicity with Transparent Costs

What It Offers

  • No Infrastructure Management: Cloud providers handle servers, scaling, backups, and updates.
  • Automated Scalability: Built-in elasticity for unpredictable workloads (e.g., handling 1M+ samples/sec during traffic spikes).
  • Integrated Tooling: Native dashboards (e.g., Grafana), alerting, and pre-built integrations with cloud services.

Cost Structure
Hosted services charge primarily based on metrics ingestion volume and retention duration:

  • Per-sample pricing:
  • AWS Managed Service for Prometheus (AMP): ~$0.03 per million samples ingested.
  • Google Cloud Managed Service for Prometheus: Pricing varies by region (e.g., $0.03–$0.06 per million samples).
  • Grafana Cloud: Starts at $29/month for 15k samples/sec (includes Grafana dashboards).
  • Retention costs: Additional fees for storing data beyond default periods (e.g., $0.03/GB/month on AWS).

Example Cost Calculation

  • Scenario: 50,000 samples/sec.
  • Daily samples: 50,000 * 86,400 = 4.32B samples/day.
  • Monthly ingestion cost (AWS AMP):
    4.32B * 30 * $0.03 / 1M = **$3,888/month**.
  • Retention (30 days, 1TB stored): ~$30/month.
  • Total: ~$3,918/month.

Cost Considerations

  • Volume spikes: Sudden traffic surges (e.g., Black Friday) can multiply costs.
  • Optimization levers: Filtering unnecessary metrics or adjusting scrape intervals reduces ingestion.
  • Hidden fees: API calls, inter-region data transfer, or premium support add to bills.

Self-Managed Prometheus: Lower Costs at Scale, Higher Effort

What It Offers

  • Full Control: Customize retention (e.g., 180+ days), storage backends (eCS2, S3), and scrape configurations.
  • Cost Efficiency for High Volume: Fixed infrastructure costs become economical at scale (e.g., 100M+ samples/day).
  • Data Sovereignty: Control data location and encryption for compliance (GDPR, HIPAA).

Cost Structure

  • Infrastructure:
  • Servers: EC2/GCP VM costs (e.g., 3 x r5.large instances @ ~$250/month each = $750/month).
  • Storage: S3/EBS (~$23/TB/month) or block storage for local TSDB.
  • Tools: Thanos/Cortex/Mimir for long-term storage (adds ~20% overhead).
  • Labor: DevOps/SRE time for setup, scaling, and troubleshooting (often 10–20 hours/month).

Example Cost Calculation

  • Scenario: 50,000 samples/sec.
  • Servers: 3 x r5.large instances ($750/month).
  • Storage: 10TB/month (~$230).
  • Labor: 15 hours/month at $100/hour = $1,500.
  • Total: ~$2,480/month.

Cost Considerations

  • Economies of scale: Marginal costs decrease as volume grows (e.g., 500,000 samples/sec may cost ~$5k/month vs. $40k+ hosted).
  • Upfront effort: Initial setup (Thanos, HA) requires significant time investment.

Key Decision Matrix: Hosted vs. Self-Managed

FactorHostedSelf-ManagedCost at 50k samples/sec ~$4,000/month ~$2,500/month (infra + labor) Scalability Automatic, no effort Manual sharding, load balancing required Compliance Limited to provider certifications Full control over data residency Maintenance Zero operational toil High (upgrades, troubleshooting) Customization Restricted by provider rules Unlimited (adjust scrape intervals, etc.)

When to Choose Hosted

  • Prioritize simplicity: Small teams or startups lacking DevOps resources.
  • Unpredictable workloads: Traffic spikes (e.g., viral apps, event-driven systems).
  • Short-term projects: Proof-of-concepts or ephemeral environments.

When to Choose Self-Managed

  • High-volume, steady workloads: Cost savings justify operational effort.
  • Strict compliance needs: Data must reside in specific regions or on-prem.
  • Custom requirements: Unique retention policies or integration with legacy systems.

Conclusion

Hosted Prometheus simplifies monitoring but scales in cost with metrics volume. Self-managed demands expertise but offers long-term savings and control. To decide:

  1. Calculate your current samples/sec using:
    promql sum(rate(scrape_samples_scraped{job!=""}[5m]))
  2. Model costs: Compare hosted pricing against self-managed infrastructure + labor.
  3. Evaluate compliance and team capacity: Can your engineers manage a distributed TSDB?

Still unsure? Start with hosted for low-volume use cases, then reassess as your needs grow. For enterprises, a hybrid approach (hosted for prod, self-managed for dev) often balances cost and control.

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