Drop CephNodeDiskspaceWarning

Sem-Ver: bugfix
Change-Id: I194bbfae3c1cc0dd36d068e143d685051fba4765
diff --git a/releasenotes/notes/cleanup-ceph-prom-alerts-3c020e3021d4fcea.yaml b/releasenotes/notes/cleanup-ceph-prom-alerts-3c020e3021d4fcea.yaml
new file mode 100644
index 0000000..f6c76e9
--- /dev/null
+++ b/releasenotes/notes/cleanup-ceph-prom-alerts-3c020e3021d4fcea.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - Drop ``CephNodeDiskspaceWarning`` alerts since they already have better
+    coverage through other alerts.
diff --git a/roles/kube_prometheus_stack/files/prometheus_alerts.yml b/roles/kube_prometheus_stack/files/prometheus_alerts.yml
index f1eb420..067f533 100644
--- a/roles/kube_prometheus_stack/files/prometheus_alerts.yml
+++ b/roles/kube_prometheus_stack/files/prometheus_alerts.yml
@@ -2,6 +2,8 @@
 #
 #               * Dropped `CephNodeNetworkPacketDrops` due to noisy alerts with
 #                 no actionable items to fix it.
+#               * Dropped `CephNodeDiskspaceWarning` because we already have a
+#                 few alerts like `NodeFilesystemSpaceFillingUp`, etc.
 #
 #               https://raw.githubusercontent.com/ceph/ceph/v16.2.9/monitoring/ceph-mixin/prometheus_alerts.yml
 
@@ -670,23 +672,6 @@
             Node {{ $labels.instance }} experiences packet errors > 0.01% or
             > 10 packets/s on interface {{ $labels.device }}.
 
-      # Restrict to device names beginning with '/' to skip false alarms from
-      # tmpfs, overlay type filesystems
-      - alert: CephNodeDiskspaceWarning
-        expr: |
-          predict_linear(node_filesystem_free_bytes{device=~"/.*"}[2d], 3600 * 24 * 5) *
-          on(instance) group_left(nodename) node_uname_info < 0
-        labels:
-          severity: warning
-          type: ceph_default
-          oid: 1.3.6.1.4.1.50495.1.2.1.8.4
-        annotations:
-          summary: Host filesystem freespace is getting low
-          description: >
-            Mountpoint {{ $labels.mountpoint }} on {{ $labels.nodename }}
-            will be full in less than 5 days assuming the average fill-up
-            rate of the past 48 hours.
-
       - alert: CephNodeInconsistentMTU
         expr: |
           node_network_mtu_bytes * (node_network_up{device!="lo"} > 0) ==