mgr/prometheus: metrics header for standby module

PR #65245 drop the header set for standby module,
we should still have it.

Fixes: https://tracker.ceph.com/issues/74149
Signed-off-by: Nitzan Mordechai <nmordech@ibm.com>

diff --git a/src/pybind/mgr/prometheus/module.py b/src/pybind/mgr/prometheus/module.py
index 679c7fa894e5dabe7fc01a83687f4a9b36b8866e..76ee581aad926ba515ae9d1b725e289514e93555 100644 (file)
--- a/src/pybind/mgr/prometheus/module.py
+++ b/src/pybind/mgr/prometheus/module.py
@@ -2323,6 +2323,7 @@ class StandbyModule(MgrStandbyModule):
 
             @cherrypy.expose
             def metrics(self) -> str:
+                cherrypy.response.headers['Content-Type'] = 'text/plain'
                 return ''
 
         cherrypy.tree.mount(Root(), '/', {})