added keepalive to DatabaseManager

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

.changeset/eleven-bees-marry.md

@@ -0,0 +1,6 @@
+---
+'@backstage/backend-common': patch
+---
+
+Added a keep-alive refresh loop to the `DatabaseManager`, keeping the connection
+pool up.

.changeset/famous-hounds-sit.md

@@ -0,0 +1,6 @@
+---
+'@backstage/backend-common': patch
+---
+
+The options part of `DatabaseManager.fromConfig` now accepts an optional logger
+field.

.changeset/shaggy-vans-repeat.md

@@ -0,0 +1,18 @@
+---
+'@backstage/create-app': patch
+---
+
+The options part of `DatabaseManager.fromConfig` now accepts an optional logger
+field. You may want to supply that logger in your backend initialization code to
+ensure that you can get relevant logging data when things happen related to the
+connection pool.
+
+In `packages/backend/src/index.ts`:
+
+```diff
+ function makeCreateEnv(config: Config) {
+   const root = getRootLogger();
+   ...
+-  const databaseManager = DatabaseManager.fromConfig(config);
++  const databaseManager = DatabaseManager.fromConfig(config, { logger: root });
+```