mgr/dashboard: prevent alert redirect

Prevent Alertmanager alerts from being redirected to the active mgr
dashboard instance. There are two reasons for it:

1. It doesn't bring any additional benefit. The Alertmanager config
   includes all available mgr instances - active and passive ones. In
   case of an alert, it will be sent to all of them. It ensures that
   the active mgr dashboard will receive the alert in any case.
2. The redirect URL includes the mgr IP and NOT the FQDN. This leads
   to issues in environments where an SSL certificate is configured and
   matches the FQDNs, only.

Fixes: https://tracker.ceph.com/issues/56401
Signed-off-by: Tatjana Dehler <tdehler@suse.com>
(cherry picked from commit 965005e0789e566ccadce7a326b0e197ab8d7f5f)

diff --git a/src/pybind/mgr/dashboard/module.py b/src/pybind/mgr/dashboard/module.py
index 96e447c6d9287450def6ba78b464a2309eae36a3..9d3b0ee5b2c49f3f19cbfe2bc09ab9d2bf4f5980 100644 (file)
--- a/src/pybind/mgr/dashboard/module.py
+++ b/src/pybind/mgr/dashboard/module.py
@@ -511,6 +511,13 @@ class StandbyModule(MgrStandbyModule, CherryPyConfig):
             def default(self, *args, **kwargs):
                 if module.get_module_option('standby_behaviour', 'redirect') == 'redirect':
                     active_uri = module.get_active_uri()
+
+                    if cherrypy.request.path_info.startswith('/api/prometheus_receiver'):
+                        module.log.debug("Suppressed redirecting alert to active '%s'",
+                                         active_uri)
+                        cherrypy.response.status = 204
+                        return None
+
                     if active_uri:
                         module.log.info("Redirecting to active '%s'", active_uri)
                         raise cherrypy.HTTPRedirect(active_uri)