Merge pull request ceph#42017 from Daniel-Pivonka/cephadm-orch-host-d…

…rain

mgr/cephadm: add ceph orch host drain and limit host removal to empty hosts

Reviewed-by: Adam King <[email protected]>

doc/cephadm/host-management.rst

@@ -64,48 +64,35 @@ To add each new host to the cluster, perform two steps:
 Removing Hosts
 ==============
 
-If the node that want you to remove is running OSDs, make sure you remove the OSDs from the node.
+A host can safely be removed from a the cluster once all daemons are removed from it.
 
-To remove a host from a cluster, do the following:
+To drain all daemons from a host do the following:
 
-For all Ceph service types, except for ``node-exporter`` and ``crash``, remove
-the host from the placement specification file (for example, cluster.yml).
-For example, if you are removing the host named host2, remove all occurrences of
-``- host2`` from all ``placement:`` sections.
-
-Update:
+.. prompt:: bash #
 
-.. code-block:: yaml
+  ceph orch host drain *<host>*
 
-  service_type: rgw
-  placement:
-    hosts:
-    - host1
-    - host2
+The '_no_schedule' label will be applied to the host. See :ref:`cephadm-special-host-labels`
 
-To:
+All osds on the host will be scheduled to be removed. You can check osd removal progress with the following:
 
-.. code-block:: yaml
+.. prompt:: bash #
 
+  ceph orch osd rm status
 
-  service_type: rgw
-  placement:
-    hosts:
-    - host1
+see :ref:`cephadm-osd-removal` for more details about osd removal
 
-Remove the host from cephadm's environment:
+You can check if there are no deamons left on the host with the following:
 
 .. prompt:: bash #
 
-  ceph orch host rm host2
-
+  ceph orch ps <host> 
 
-If the host is running ``node-exporter`` and crash services, remove them by running
-the following command on the host:
+Once all daemons are removed you can remove the host with the following:
 
 .. prompt:: bash #
 
-  cephadm rm-daemon --fsid CLUSTER_ID --name SERVICE_NAME
+  ceph orch host rm <host>
 
 .. _orchestrator-host-labels:
 

doc/cephadm/osd.rst

@@ -211,6 +211,7 @@ If you want to avoid this behavior (disable automatic creation of OSD on availab
 
 * For cephadm, see also :ref:`cephadm-spec-unmanaged`.
 
+.. _cephadm-osd-removal:
 
 Remove an OSD
 =============

src/pybind/mgr/cephadm/module.py

@@ -1463,6 +1463,22 @@ def remove_host(self, host):
 
         :param host: host name
         """
+        # Verify if it is possible to remove the host safely
+        daemons = self.cache.get_daemons_by_host(host)
+        if daemons:
+            self.log.warning(f"Blocked {host} removal. Daemons running: {daemons}")
+
+            daemons_table = ""
+            daemons_table += "{:<20} {:<15}\n".format("type", "id")
+            daemons_table += "{:<20} {:<15}\n".format("-" * 20, "-" * 15)
+            for d in daemons:
+                daemons_table += "{:<20} {:<15}\n".format(d.daemon_type, d.daemon_id)
+
+            return "Not allowed to remove %s from cluster. " \
+                "The following daemons are running in the host:" \
+                "\n%s\nPlease run 'ceph orch host drain %s' to remove daemons from host" % (
+                    host, daemons_table, host)
+
         self.inventory.rm_host(host)
         self.cache.rm_host(host)
         self._reset_con(host)
@@ -2564,3 +2580,25 @@ def remove_osds_status(self) -> List[OSD]:
         The CLI call to retrieve an osd removal report
         """
         return self.to_remove_osds.all_osds()
+
+    @handle_orch_error
+    def drain_host(self, hostname):
+        # type: (str) -> str
+        """
+        Drain all daemons from a host.
+        :param host: host name
+        """
+        self.add_host_label(hostname, '_no_schedule')
+
+        daemons: List[orchestrator.DaemonDescription] = self.cache.get_daemons_by_host(hostname)
+
+        osds_to_remove = [d.daemon_id for d in daemons if d.daemon_type == 'osd']
+        self.remove_osds(osds_to_remove)
+
+        daemons_table = ""
+        daemons_table += "{:<20} {:<15}\n".format("type", "id")
+        daemons_table += "{:<20} {:<15}\n".format("-" * 20, "-" * 15)
+        for d in daemons:
+            daemons_table += "{:<20} {:<15}\n".format(d.daemon_type, d.daemon_id)
+
+        return "Scheduled to remove the following daemons from host '{}'\n{}".format(hostname, daemons_table)

src/pybind/mgr/orchestrator/_interface.py

@@ -351,6 +351,14 @@ def remove_host(self, host: str) -> OrchResult[str]:
         """
         raise NotImplementedError()
 
+    def drain_host(self, hostname: str) -> OrchResult[str]:
+        """
+        drain all daemons from a host
+
+        :param hostname: hostname
+        """
+        raise NotImplementedError()
+
     def update_host_addr(self, host: str, addr: str) -> OrchResult[str]:
         """
         Update a host's address

src/pybind/mgr/orchestrator/module.py

@@ -352,6 +352,13 @@ def _remove_host(self, hostname: str) -> HandleCommandResult:
         raise_if_exception(completion)
         return HandleCommandResult(stdout=completion.result_str())
 
+    @_cli_write_command('orch host drain')
+    def _drain_host(self, hostname: str) -> HandleCommandResult:
+        """drain all daemons from a host"""
+        completion = self.drain_host(hostname)
+        raise_if_exception(completion)
+        return HandleCommandResult(stdout=completion.result_str())
+
     @_cli_write_command('orch host set-addr')
     def _update_set_addr(self, hostname: str, addr: str) -> HandleCommandResult:
         """Update a host address"""