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
+
+
+NOTE: This is for informational purposes only. This doesn't account for all
+costs of operating. It gives an approximate sizing of the cost. This document
+should be used to assist in understanding how to calculate the cost of
+deploying this service.
+
+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.
+
+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).
+
+These estimates also don't include CDN costs. For simplicity they assume
+direct access to Cloud Storage.
+
+# 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
+https://cloud.google.com/run/pricing
+
+There are multiple containers needed for a complete deployment: 
+
+* Export Cleanup
+* Exposure Cleanup
+* Export
+* Exposure
+* Federation In
+* Federation Out
+
+Let's assume we run ~4 containers constantly as much of the operation is batch
+and won't account for constant use. Also, we can reflect on the default
+[terraform resource limits](https:/google/exposure-notifications-server/blob/master/terraform/service_federationin.tf#L63)
+of 2 CPU and 1G memory per container.
+
+**Projected Monthly Cost: $500 - 1000**
+
+## SQL Database Costs
+https://cloud.google.com/sql/pricing
+
+The default size for SQL Database is configured to:
+* 8 vCPU
+* 30720 MB Memory
+* 256 GB SSD
+
+The cost of this component can vary greatly on the scale is configured to.
+Depending on the needed scale of your deployment this could require a different
+configuration.
+
+**Project Monthly Cost: $1000 - $1250**
+
+## Storage Costs
+https://cloud.google.com/storage/pricing
+
+### Data Storage Cost
+The last 14 days of batches are stored with older batches being deleted. This
+is a small amount of data storage.
+
+**Projected Monthly Cost: $0 - $20.00**
+
+### Network Usage Cost
+Each day every user will need to download a batch. This means that roughly
+5M * 3.5MB
+$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 - $20.00**
+
+#### Class B
+$0.004 per 10,000 operations
+
+Relevant operations from this include `GET` requests for key batches.
+
+For each user, there will be a minimum of one `GET` operation per day.
+
+**Projected Monthly Cost: $50 - $100**
+