Add appMigrationMetadata utils

packages/server/src/appMigrations/appMigrationMetadata.ts

@@ -0,0 +1,39 @@
+import { Duration, cache, db, env } from "@budibase/backend-core"
+import { Database, App, DocumentType, Document } from "@budibase/types"
+
+export interface AppMigrationDoc extends Document {
+  version: string
+}
+
+const EXPIRY_SECONDS = Duration.fromDays(1).toSeconds()
+
+async function populateFromDB(appId: string) {
+  return db.doWithDB(
+    appId,
+    (db: Database) => {
+      return db.get<App>(DocumentType.APP_MIGRATION_METADATA)
+    },
+    { skip_setup: true }
+  )
+}
+
+export async function getAppMigrationMetadata(appId: string): Promise<string> {
+  const cacheKey = `appmigrations_${env.VERSION}_${appId}`
+
+  let metadata: AppMigrationDoc | undefined = await cache.get(cacheKey)
+  if (!metadata) {
+    try {
+      metadata = await populateFromDB(appId)
+    } catch (err: any) {
+      if (err.status !== 404) {
+        throw err
+      }
+
+      metadata = { version: "" }
+    }
+
+    await cache.store(cacheKey, metadata, EXPIRY_SECONDS)
+  }
+
+  return metadata.version
+}

packages/types/src/documents/document.ts

@@ -37,6 +37,7 @@ export enum DocumentType {
   USER_FLAG = "flag",
   AUTOMATION_METADATA = "meta_au",
   AUDIT_LOG = "al",
+  APP_MIGRATION_METADATA = "_design/migrations",
 }
 
 // these are the core documents that make up the data, design