zero: group funcs that need run within a lease

internal/zero/leaser/monitor.go

@@ -0,0 +1,37 @@
+package leaser
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/pomerium/pomerium/pkg/grpc/databroker"
+)
+
+const typeStr = "pomerium.io/zero/leaser"
+
+// databrokerChangeMonitor runs infinite sync loop to see if there is any change in databroker
+// it doesn't really syncs anything, just checks if the underlying databroker has changed
+func (c *service) databrokerChangeMonitor(ctx context.Context) error {
+	_, recordVersion, serverVersion, err := databroker.InitialSync(ctx, c.GetDataBrokerServiceClient(), &databroker.SyncLatestRequest{
+		Type: typeStr,
+	})
+	if err != nil {
+		return fmt.Errorf("error during initial sync: %w", err)
+	}
+
+	stream, err := c.GetDataBrokerServiceClient().Sync(ctx, &databroker.SyncRequest{
+		Type:          typeStr,
+		ServerVersion: serverVersion,
+		RecordVersion: recordVersion,
+	})
+	if err != nil {
+		return fmt.Errorf("error calling sync: %w", err)
+	}
+
+	for {
+		_, err := stream.Recv()
+		if err != nil {
+			return fmt.Errorf("error receiving record: %w", err)
+		}
+	}
+}