Fix extension installed check for already migrated DB schema

pkg/pgmodel/end_to_end_tests/migrate_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/jackc/pgx/v4/pgxpool"
 	"github.com/timescale/timescale-prometheus/pkg/internal/testhelpers"
+	"github.com/timescale/timescale-prometheus/pkg/pgmodel"
 )
 
 const (
@@ -37,6 +38,16 @@ func TestMigrateTwice(t *testing.T) {
 	}
 	testhelpers.WithDB(t, *testDatabase, testhelpers.NoSuperuser, func(db *pgxpool.Pool, t testing.TB, connectURL string) {
 		performMigrate(t, connectURL)
+		if *useExtension && !pgmodel.ExtensionIsInstalled {
+			t.Errorf("extension is not installed, expected it to be installed")
+		}
+
+		//reset the flag to make sure it's set correctly again.
+		pgmodel.ExtensionIsInstalled = false
+
 		performMigrate(t, connectURL)
+		if *useExtension && !pgmodel.ExtensionIsInstalled {
+			t.Errorf("extension is not installed, expected it to be installed")
+		}
 	})
 }

pkg/pgmodel/migrate.go

@@ -90,6 +90,7 @@ func (p prefixedNames) getNames() []string {
 func Migrate(db *pgxpool.Pool, versionInfo VersionInfo) (err error) {
 	migrateMutex.Lock()
 	defer migrateMutex.Unlock()
+	ExtensionIsInstalled = false
 
 	// Getting an early connection to install the extra extension.
 	// TODO: Investigate why this is required. Installing the extension on the
@@ -115,6 +116,10 @@ func Migrate(db *pgxpool.Pool, versionInfo VersionInfo) (err error) {
 
 	// If already at correct version, nothing to migrate.
 	if dbVersion.Compare(appVersion) == 0 {
+		installExtension(conn)
+
+		metadataUpdate(db, ExtensionIsInstalled, "version", versionInfo.Version)
+		metadataUpdate(db, ExtensionIsInstalled, "commit_hash", versionInfo.CommitHash)
 		return nil
 	}
 
@@ -155,13 +160,7 @@ func Migrate(db *pgxpool.Pool, versionInfo VersionInfo) (err error) {
 		return fmt.Errorf("unable to commit migration transaction: %w", err)
 	}
 
-	_, extErr := conn.Exec(context.Background(), fmt.Sprintf(extensionInstall, extSchema))
-	if extErr != nil {
-		log.Warn("msg", "timescale_prometheus_extra extension not installed", "cause", extErr)
-		ExtensionIsInstalled = false
-	} else {
-		ExtensionIsInstalled = true
-	}
+	installExtension(conn)
 
 	metadataUpdate(db, ExtensionIsInstalled, "version", versionInfo.Version)
 	metadataUpdate(db, ExtensionIsInstalled, "commit_hash", versionInfo.CommitHash)
@@ -361,6 +360,16 @@ func upgradeVersion(tx pgx.Tx, from, to semver.Version) error {
 	return nil
 }
 
+func installExtension(conn *pgxpool.Conn) {
+	_, extErr := conn.Exec(context.Background(), fmt.Sprintf(extensionInstall, extSchema))
+	if extErr != nil {
+		log.Warn("msg", "timescale_prometheus_extra extension not installed", "cause", extErr)
+		ExtensionIsInstalled = false
+	} else {
+		ExtensionIsInstalled = true
+	}
+}
+
 func setDBVersion(tx pgx.Tx, version *semver.Version) error {
 	if _, err := tx.Exec(context.Background(), truncateMigrationsTable); err != nil {
 		return fmt.Errorf("unable to truncate migrations table: %w", err)