Fix demoted user cannot execute metal-db health check. (#543)

* Fix demoted user cannot execute metal-db health check.

* Use ctx.

Author: Gerrit91

cmd/metal-api/internal/datastore/health.go

@@ -40,7 +40,7 @@ func (rs *RethinkStore) Check(ctx context.Context) (rest.HealthResult, error) {
 		return returnStatus(err)
 	}
 
-	cursor, err := r.DB("rethinkdb").Table("server_status").Field("process").Field("version").Run(rs.session)
+	cursor, err := r.DB("rethinkdb").Table("server_status").Field("process").Field("version").Run(rs.session, r.RunOpts{Context: ctx})
 	if err != nil {
 		return returnStatus(err)
 	}

cmd/metal-api/internal/datastore/rethinkdb.go

@@ -140,6 +140,10 @@ func (rs *RethinkStore) initializeTables(opts r.TableCreateOpts) error {
 	if err != nil {
 		return err
 	}
+	_, err = r.DB("rethinkdb").Grant(DemotedUser, map[string]interface{}{"read": true}).RunWrite(rs.session)
+	if err != nil {
+		return err
+	}
 
 	// integer pools
 	err = rs.GetVRFPool().initIntegerPool(rs.log)