doc/cephadm: Per-service and per-daemon events

Signed-off-by: Sebastian Wagner <sebastian.wagner@suse.com>

doc/cephadm/troubleshooting.rst

@@ -27,6 +27,49 @@ This will disable all of the ``ceph orch ...`` CLI commands but the previously
 deployed daemon containers will still continue to exist and start as they
 did before.
 
+
+Per-service and per-daemon events
+---------------------------------
+
+In order to aid debugging failed daemon deployments, cephadm stores 
+events per service and per daemon. They often contain relevant information::
+
+  ceph orch ls --service_name=<service-name> --format yaml
+
+for example:
+
+.. code-block:: yaml
+
+  service_type: alertmanager
+  service_name: alertmanager
+  placement:
+    hosts:
+    - unknown_host
+  status:
+    ...
+    running: 1
+    size: 1
+  events:
+  - 2021-02-01T08:58:02.741162 service:alertmanager [INFO] "service was created"
+  - '2021-02-01T12:09:25.264584 service:alertmanager [ERROR] "Failed to apply: Cannot
+    place <AlertManagerSpec for service_name=alertmanager> on unknown_host: Unknown hosts"'
+
+Or per daemon::
+
+  ceph orch ceph --service-type mds --daemon-id=hostname.ppdhsz --format yaml
+
+.. code-block:: yaml
+
+  daemon_type: mds
+  daemon_id: cephfs.hostname.ppdhsz
+  hostname: hostname
+  status_desc: running
+  ...
+  events:
+  - 2021-02-01T08:59:43.845866 daemon:mds.cephfs.hostname.ppdhsz [INFO] "Reconfigured
+    mds.cephfs.hostname.ppdhsz on host 'hostname'"
+
+
 Checking cephadm logs
 ---------------------