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.

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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.

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Key Decision Matrix: Hosted vs. Self-Managed

Factor** Hosted *Self-Managed* Cost 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.)

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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.

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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.

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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?

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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.