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fix(cron): gate startup on schema readiness before opening the pooled context - #329
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… context The Cron host does not own migrations (the API is the sole migrator), but its OpenShockContext binds Postgres enum types (email_status, email_type, ...) to CLR enums by name via MapEnum<T>(). Npgsql resolves those names against the type catalog it loads on the pooled data source's first connection and caches for the life of the process. If that first connection happens before the migrator has created a newly-added enum, every query using it fails permanently with 'data type name ... could not be found in the types that were loaded by Npgsql' until the process restarts - which is exactly what hit the EmailOutboxDeliveryJob claim query during the outbox rollout. Add WaitForOpenShockSchemaReady (polls GetPendingMigrationsAsync with capped backoff and a timeout) and call it in the Cron host right after the common middleware, before Hangfire or any job opens the pooled context. Cron performs no schema writes; the API stays the sole migrator.
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Pull request overview
Adds a startup gate to the Cron host so it won’t open an enum-mapped OpenShockContext pool until the database schema (migrations) is fully applied by the API host, preventing Npgsql from permanently caching “missing” Postgres enum types during deploy races.
Changes:
- Introduces
WaitForOpenShockSchemaReady(DatabaseOptions, TimeSpan?)which pollsGetPendingMigrationsAsync()with capped exponential backoff and a timeout. - Calls the new gate in
Cron/Program.csimmediately afterUseCommonOpenShockMiddleware()and before Hangfire/job execution can touch the pooled context.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
Cron/Program.cs |
Blocks Cron startup until schema is migration-complete before any job execution can open/use the pooled EF Core context. |
Common/OpenShockMiddlewareHelper.cs |
Adds a reusable schema-readiness wait helper for non-migrator hosts to avoid enum type-catalog caching races. |
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Problem
The Cron host was failing every
EmailOutboxDeliveryJobclaim query in production with:Root cause
OpenShockContextbinds the Postgres enum types (email_status,email_type, …) to CLR enums by name viaMapEnum<T>(). Npgsql resolves those names against the type catalog it loads on the pooled data source's first connection, then caches it for the life of the process.The Cron host does not own migrations — the API is the sole migrator (
API/Program.cscallsApplyPendingOpenShockMigrations; Cron never did). So during the outbox rollout, Cron's data source loaded its type catalog before the API had applied the migration that creates those enums. The missing type was cached as absent, and every query using it failed permanently until the process was restarted.This is a deploy-time race that recurs whenever a new enum consumed by Cron is added.
Fix
WaitForOpenShockSchemaReady(DatabaseOptions)inCommon/OpenShockMiddlewareHelper.cs— pollsGetPendingMigrationsAsync()with capped backoff and a timeout.Cron/Program.csright afterUseCommonOpenShockMiddleware(), before Hangfire or any job opens the pooled context.Cron performs no schema writes; the API stays the sole migrator. This closes the race window without reintroducing a cross-host migration write-race.
Notes
AddPooledDbContextFactorybareUseNpgsqlinAddOpenShockDBis dead config (TryAddmeans the enum-mapped pool options win), so it was not the cause — left untouched here.