[PATCH pve-manager v4 2/7] fix #6816: api: ceph: create 'client.exporter' w/ keyring

["Max R. Carrara" <m.carrara@proxmox.com>]

... when creating the first MON.

Similar to `ceph-crash.service` [0], create or update the keyring for
the `ceph-exporter` daemon using a new Ceph auth entity called
`client.exporter` when creating the first MON.

Its keyring is placed at `/etc/pve/ceph/ceph.client.exporter.keyring`.

The `ceph-exporter` daemon only needs read access to MONs. Found this
out during testing; this isn't explicitly documented anywhere AFAIK.

In case the daemon requires more capabilities in the future, I
recommend updating them via a separate helper that wraps the `ceph
auth caps` command via `PVE::RADOS`. However, because all this daemon
does is expose a metrics endpoint `http://$HOST:9926/metrics`, I doubt
that it needs any additional capabilities any time soon.

[0]: https://lore.proxmox.com/pve-devel/20240402145523.683008-11-m.carrara@proxmox.com/

Fixes: #6816
Signed-off-by: Max R. Carrara <m.carrara@proxmox.com>
---
 PVE/API2/Ceph/MON.pm |  9 +++++++++
 PVE/Ceph/Tools.pm    | 15 +++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/PVE/API2/Ceph/MON.pm b/PVE/API2/Ceph/MON.pm
index 68abd502..04cfc7f1 100644
--- a/PVE/API2/Ceph/MON.pm
+++ b/PVE/API2/Ceph/MON.pm
@@ -536,6 +536,15 @@ __PACKAGE__->register_method({
                             cfs_write_file('ceph.conf', $cfg);
                         };
                         warn "Unable to configure keyring for ceph-crash.service: $@" if $@;
+
+                        print "Configuring keyring for ceph-exporter.service\n";
+                        eval {
+                            PVE::Ceph::Tools::create_or_update_exporter_keyring_file();
+                            $cfg->{'client.exporter'}->{keyring} =
+                                '/etc/pve/ceph/$cluster.$name.keyring';
+                            cfs_write_file('ceph.conf', $cfg);
+                        };
+                        warn "Unable to configure keyring for ceph-exporter.service: $@" if $@;
                     }
 
                     eval { PVE::Ceph::Services::ceph_service_cmd('enable', $monsection) };
diff --git a/PVE/Ceph/Tools.pm b/PVE/Ceph/Tools.pm
index 206921c1..32c1a989 100644
--- a/PVE/Ceph/Tools.pm
+++ b/PVE/Ceph/Tools.pm
@@ -23,6 +23,7 @@ my $ceph_cfgpath = "$ceph_cfgdir/$ccname.conf";
 my $pve_ceph_cfgdir = "/etc/pve/ceph";
 
 my $pve_ceph_crash_key_path = "$pve_ceph_cfgdir/$ccname.client.crash.keyring";
+my $pve_ceph_exporter_key_path = "$pve_ceph_cfgdir/$ccname.client.exporter.keyring";
 my $pve_mon_key_path = "/etc/pve/priv/$ccname.mon.keyring";
 my $pve_ckeyring_path = "/etc/pve/priv/$ccname.client.admin.keyring";
 my $ckeyring_path = "/etc/ceph/ceph.client.admin.keyring";
@@ -49,6 +50,7 @@ my $config_values = {
 my $config_files = {
     pve_ceph_cfgpath => $pve_ceph_cfgpath,
     pve_ceph_crash_key_path => $pve_ceph_crash_key_path,
+    pve_ceph_exporter_key_path => $pve_ceph_exporter_key_path,
     pve_mon_key_path => $pve_mon_key_path,
     pve_ckeyring_path => $pve_ckeyring_path,
     ceph_bootstrap_osd_keyring => $ceph_bootstrap_osd_keyring,
@@ -569,6 +571,19 @@ sub create_or_update_crash_keyring_file {
     return 0;
 }
 
+sub create_or_update_exporter_keyring_file {
+    my ($rados) = @_;
+
+    my $entity = 'client.exporter';
+    my $caps = [
+        mon => 'allow r',
+    ];
+
+    return create_or_update_keyring_file(
+        $pve_ceph_exporter_key_path, $entity, $caps, $rados,
+    );
+}
+
 # get ceph-volume managed osds
 sub ceph_volume_list {
     my $result = {};
-- 
2.47.3