Implement Health Checks for Auth Service

[willvelida]

Parent Issue

Part of #119 - Implement Custom Health Probes and Dependency Health Checks

Overview

Apply the proven health check pattern from #136 (Weight API) to the Auth Service. Note: Auth Service does not depend on Fitbit API, so it only includes Cosmos DB and Key Vault health checks.

Scope

• src/Biotrackr.Auth.Svc/
• infra/apps/auth-service/main.bicep

Tasks

1. Install Health Check Packages

Add to Biotrackr.Auth.Svc.csproj:

<PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="9.0.0" />
<PackageReference Include="AspNetCore.HealthChecks.CosmosDb" Version="8.0.1" />
<PackageReference Include="AspNetCore.HealthChecks.AzureKeyVault" Version="8.0.1" />

2. Implement Health Check Endpoints

Apply proven pattern from #136 (minus Fitbit dependency):

• Health checks for self, Cosmos DB (lightweight), Key Vault only
• No Fitbit API health check (Auth Service doesn't use Fitbit)
• Configure /health/live, /health/ready, /health/startup endpoints

3. Update Bicep Configuration

Update infra/apps/auth-service/main.bicep:

• Apply same probe configuration as Weight Service

4. Add Integration Tests

• Verify health endpoints return correct status codes
• Test dependency failure scenarios (Cosmos DB, Key Vault)

Acceptance Criteria

• Health check packages installed
• /health/live, /health/ready, /health/startup endpoints implemented
• Cosmos DB and Key Vault health checks configured (no Fitbit)
• Bicep probe configuration updated
• Integration tests pass
• Deployed to dev environment and validated

Dependencies

• Depends on Implement Health Checks for Weight API #136 (Weight API) - Pattern must be established first

References

• ASP.NET Core Health Checks
• Container Apps Health Probes

Notes

Auth Service has simpler health checks since it doesn't integrate with Fitbit API.