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>
(cherry picked from commit 2ef12b2ffa6dd11041e7120febcbd62338ec8cd3)

diff --git a/src/pybind/mgr/prometheus/module.py b/src/pybind/mgr/prometheus/module.py
index 3b5e36bda3c062b53a7a53e810ae64067ba350f3..6a871f0599e492a3e7e493717b9df3f534ddbf3f 100644 (file)
--- a/src/pybind/mgr/prometheus/module.py
+++ b/src/pybind/mgr/prometheus/module.py
@@ -2095,6 +2095,7 @@ class Module(MgrModule, OrchestratorClientMixin):
                 # Lock the function execution
                 assert isinstance(_global_instance, Module)
                 with _global_instance.collect_lock:
+                    cherrypy.response.headers['Content-Type'] = 'text/plain; charset=utf-8'
                     return self._metrics(_global_instance)
 
             @staticmethod
@@ -2265,6 +2266,7 @@ class StandbyModule(MgrStandbyModule):
 
             @cherrypy.expose
             def metrics(self) -> str:
+                cherrypy.response.headers['Content-Type'] = 'text/plain; charset=utf-8'
                 return ''
 
         cherrypy.tree.mount(Root(), '/', {})