feat: expose postgres version (#7041)

Adds a postgres_version gauge to allow us to see postgres_version in
prometheus and to post it upstream when version checking. Depends on
https://github.com/bricks-software/version-function/pull/20 to be merged
first to ensure our version-function doesn't crash when given the
postgres-version data.

src/lib/db/setting-store.ts

@@ -14,6 +14,16 @@ export default class SettingStore implements ISettingStore {
         this.logger = getLogger('settings-store.ts');
     }
 
+    async postgresVersion(): Promise<string> {
+        try {
+            const showResult = await this.db.raw('SHOW server_version');
+            return showResult?.rows[0]?.server_version || '';
+        } catch (e) {
+            this.logger.warn('Failed to fetch postgres version', e);
+            return '';
+        }
+    }
+
     async updateRow(name: string, content: any): Promise<void> {
         return this.db(TABLE)
             .where('name', name)

src/lib/metrics.ts

@@ -21,7 +21,7 @@ import {
     PROJECT_ENVIRONMENT_REMOVED,
 } from './types/events';
 import type { IUnleashConfig } from './types/option';
-import type { IUnleashStores } from './types/stores';
+import type { ISettingStore, IUnleashStores } from './types/stores';
 import { hoursToMilliseconds, minutesToMilliseconds } from 'date-fns';
 import type { InstanceStatsService } from './features/instance-stats/instance-stats-service';
 import type { ValidatedClientMetrics } from './features/metrics/shared/schema';
@@ -651,7 +651,12 @@ export default class MetricsMonitor {
             projectEnvironmentsDisabled.increment({ project_id: project });
         });
 
-        await this.configureDbMetrics(db, eventBus, schedulerService);
+        await this.configureDbMetrics(
+            db,
+            eventBus,
+            schedulerService,
+            stores.settingStore,
+        );
 
         return Promise.resolve();
     }
@@ -660,6 +665,7 @@ export default class MetricsMonitor {
         db: Knex,
         eventBus: EventEmitter,
         schedulerService: SchedulerService,
+        settingStore: ISettingStore,
     ): Promise<void> {
         if (db?.client) {
             const dbPoolMin = createGauge({
@@ -707,6 +713,13 @@ export default class MetricsMonitor {
                 'registerPoolMetrics',
                 0, // no jitter
             );
+            const postgresVersion = await settingStore.postgresVersion();
+            const database_version = createGauge({
+                name: 'postgres_version',
+                help: 'Which version of postgres is running (SHOW server_version)',
+                labelNames: ['version'],
+            });
+            database_version.labels({ version: postgresVersion }).set(1);
         }
     }
 

src/lib/services/version-service.ts

@@ -65,6 +65,7 @@ export interface IFeatureUsageInfo {
     productionChanges30: number;
     productionChanges60: number;
     productionChanges90: number;
+    postgresVersion: string;
 }
 
 export default class VersionService {
@@ -260,6 +261,7 @@ export default class VersionService {
             featureImports,
             userActive,
             productionChanges,
+            postgresVersion,
         ] = await Promise.all([
             this.featureToggleStore.count({
                 archived: false,
@@ -282,6 +284,7 @@ export default class VersionService {
             this.eventStore.filteredCount({ type: FEATURES_IMPORTED }),
             this.userStats(),
             this.productionChanges(),
+            this.postgresVersion(),
         ]);
         const versionInfo = await this.getVersionInfo();
         const customStrategies =
@@ -315,6 +318,7 @@ export default class VersionService {
             productionChanges30: productionChanges.last30,
             productionChanges60: productionChanges.last60,
             productionChanges90: productionChanges.last90,
+            postgresVersion,
         };
         return featureInfo;
     }
@@ -336,6 +340,10 @@ export default class VersionService {
         return this.getProductionChanges();
     }
 
+    async postgresVersion(): Promise<string> {
+        return this.settingStore.postgresVersion();
+    }
+
     async hasOIDC(): Promise<boolean> {
         const settings = await this.settingStore.get<{ enabled: boolean }>(
             'unleash.enterprise.auth.oidc',

src/lib/types/stores/settings-store.ts

@@ -8,5 +8,6 @@ export interface ISettingInsert {
 export interface ISettingStore extends Store<any, string> {
     insert<T>(name: string, content: T): Promise<void>;
     updateRow(name: string, content: any): Promise<void>;
+    postgresVersion(): Promise<string>;
     get<T>(name: string): Promise<T | undefined>;
 }

src/test/fixtures/fake-setting-store.ts

@@ -38,4 +38,8 @@ export default class FakeSettingStore implements ISettingStore {
     async updateRow(name: string, content: any): Promise<void> {
         this.settings.set(name, content);
     }
+
+    async postgresVersion(): Promise<string> {
+        return Promise.resolve('fake-postgres-version');
+    }
 }