ACTOR (Aladon) - Enterprise Platform Modernization

Context

• The codebase was a legacy ~700k LOC .NET Framework 4 system.
• The product was a multi-tenant Blazor Server app.
• Each tenant included multiple sites, and each site had its own SQL database.
• Tenant and site metadata were stored in SQLite files bundled with the distribution.
• NetLicensing checks were in the login/session path.
• The Azure footprint had high monthly spend.

Challenge

• The legacy runtime and dependencies were slowing maintenance work.
• The file-based tenancy flow caused frequent setup and state issues.
• Unsafe locking and async/sync race patterns caused instability.
• Licensing checks before authentication broke session persistence.
• The Azure setup was overprovisioned for the actual workload.

Key Decisions

• Migrate to .NET 8. Why: Required modern runtime support and a safer long-term upgrade path.
• Replace SQLite tenancy metadata with Keycloak tenant management. Why: Required centralized tenant lifecycle management without fragile local files.
• Remove unsafe locking and race patterns in critical flows. Why: Required predictable behavior under concurrent load.
• Move licensing gate to post-authentication. Why: Needed a corrected session lifecycle to restore stay-logged-in behavior.
• Rationalize Azure topology around Azure SQL + Web Apps; retain VM only for SSRS and WireGuard. Why: Required lower cost without removing reporting and secure networking services.

Implementation Changes

• Migrated the platform from .NET 4 to .NET 8.
• Integrated Keycloak for tenant/site lifecycle and removed SQLite tenancy files.
• Refactored concurrency paths to remove lock contention and async/sync race hazards.
• Changed auth and licensing order to restore stable sessions.
• Right-sized Azure around Azure SQL, Web Apps, and a scoped VM role.

Results

• Azure spend reduced from approximately $7,800/month to approximately $2,400/month.
• Removed SQLite tenant file management as a recurring source of setup and release failures.
• Resolved long-standing stay-logged-in behavior by fixing auth/licensing order.
• Reduced platform instability linked to locking and race-condition paths (qualitative).

Tech Stack