Estimating Costs (WIP)

docs/_data/navigation.yml

@@ -11,6 +11,8 @@ docs:
  url: /getting-started/publishing-temporary-exposure-keys
  - title: How to Download Keys
  url: /getting-started/downloading-export-batches-keys
+ - title: Estimating the Cost of Deployment
+ url: /getting-started/estimating-costs
  - title: Design
  children:
  - title: Server Deployment Options

docs/getting-started/estimating-costs.md

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+---
+layout: default
+---
+
+# Estimating costs of hosting the Exposure Notifications Server
+
+This page explains how you might estimate the cost to deploy servers within the
+Exposure Notification Reference implementation. Cost estimates assume the use
+of Google Cloud and use
+[published pricing rates](https://cloud.google.com/pricing), but similar
+calculations could be done for other cloud providers as well as self-hosted
+machines. All prices use USD. Also, much of this is simplified. It doesn't
+fully account for free-tier exceptions, or tiered pricing. This is meant
+to assist in having an approximate idea of cost to operate. This also assumes
+the defaults at the time of authoring in [vars.tf](https:/google/exposure-notifications-server/blob/master/terraform/vars.tf).
+
+
+# Calculating the overall cost
+There are a number of variables that need to be figured out to determine cost.
+That said, the vast majority of that cost is going to be from the network
+egress. The next largest cost is likely for hosting of containers.
+
+Let's assume that we are calculating the cost of operating for an area with:
+
+* A population of 10 Million (10,000,000) people.
+* An exposure window of 14 days
+* 50% adoption of an exposure notifications system
+* 1,250 new cases daily (approxmately .01% new cases per day)
+
+From which we can derive:
+* Each new set of keys is 280 bytes (14 days * 20 bytes)
+* Each daily batch is 1,250 * 280 bytes = .35 MB
+* That file is downloaded 5 Million times per day (1.75 GB/day download) for
+ a total monthly egress of 52.5 GB.
+
+# Cloud Components and Pricing
+
+## Cloud Run Costs
+There are multiple containers needed for a complete deployment: 
+
+* Export Cleanup
+* Exposure Cleanup
+* Export
+* Exposure
+* Federation In
+* Federation Out
+
+The [cost](https://cloud.google.com/run/pricing#pricing_table) for Cloud Run
+per container per hour is:
+ * CPU: $0.00002400 / vCPU-seconds beyond free quota ($2.0736 / day)
+ * Memory: $0.00000250 / GiB-second beyond free quota ($0.215 / day)
+
+Assuming we run ~4 containers constantly, which given the batch nature of many
+may be a high estimate, and assuming we use the currently default terraform
+resource limits of 2 CPU and 1G memory per container:
+
+Projected Monthly Cost: 30 * 4 * ((2 * $2.0736) + (1 * $0.215)) = $523.46
+
+## SQL Database Costs
+Configured Size in TF: "db-custom-8-30720" with 256GB Disk
+
+Projected Monthly Cost: TBD
+
+## Storage Costs
+https://cloud.google.com/storage/pricing
+
+### Data Storage Cost
+$0.026 per GB
+
+Projected Monthly Cost: ($0.026 / GB) * (0.00035 GB * 14 days) = $0 (fractional)
+
+### Network Usage Cost
+$0.12 per GB (egress)
+
+Projected Monthly Cost: ($0.12 / GB) * (1.75GB/day * 30 days) = $6.30
+
+### Operations Cost
+There are two tiers of operations with different billing.
+
+#### Class A
+$0.05 per 10,000 operations
+
+Relevant operations from this include `INSERT`, `UPDATE`, and `LIST`. These
+will occur as part of batching of exposure keys. These operations will likely
+remain under 10,000 for storage as creation of files is batched.
+
+Projected Monthly Cost: $0.05
+
+#### Class B
+$0.004 per 10,000 operations
+
+Relevant operations from this include `GET` requests for key batches.
+
+Projected Monthly Cost: .004/10,000 * 60 Million = $24.00