From 4d629d3db60056655afa6f9549c687654eecb66d Mon Sep 17 00:00:00 2001
From: Stephen Taylor <stephen.taylor.1@att.com>
Date: Tue, 12 Oct 2021 14:36:43 -0600
Subject: [PATCH] [ceph-mon] Prevent mon-check from removing mons when down
 temporarily

A race condition exists that can cause the mon-check pod to delete
mons from the monmap that are only down temporarily. This sometimes
causes issues with the monmap when those mons come back up. This
change adds a check to see if the list of mons in the monmap is
larger than expected before removing anything. If not, the monmap
is left alone.

Change-Id: I43b186bf80741fc178c6806d24c179417d7f2406
---
 ceph-mon/Chart.yaml                           |  2 +-
 ceph-mon/templates/bin/moncheck/_start.sh.tpl | 33 +++++++++++++++++--
 releasenotes/notes/ceph-mon.yaml              |  1 +
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/ceph-mon/Chart.yaml b/ceph-mon/Chart.yaml
index daeea5cbf..4cbb703cd 100644
--- a/ceph-mon/Chart.yaml
+++ b/ceph-mon/Chart.yaml
@@ -15,6 +15,6 @@ apiVersion: v1
 appVersion: v1.0.0
 description: OpenStack-Helm Ceph Mon
 name: ceph-mon
-version: 0.1.14
+version: 0.1.15
 home: https://github.com/ceph/ceph
 ...
diff --git a/ceph-mon/templates/bin/moncheck/_start.sh.tpl b/ceph-mon/templates/bin/moncheck/_start.sh.tpl
index 65141d640..9091826c1 100644
--- a/ceph-mon/templates/bin/moncheck/_start.sh.tpl
+++ b/ceph-mon/templates/bin/moncheck/_start.sh.tpl
@@ -24,13 +24,42 @@ function check_mon_msgr2 {
  fi
 }
 
+function get_mon_count {
+  ceph mon count-metadata hostname | jq '. | length'
+}
+
+function check_mon_addrs {
+  local mon_dump=$(ceph mon dump)
+  local mon_hostnames=$(echo "${mon_dump}" | awk '/mon\./{print $3}' | sed 's/mon\.//g')
+  local mon_endpoints=$(kubectl get endpoints ceph-mon-discovery -n ceph -o json)
+  local v1_port=$(jq '.subsets[0].ports[] | select(.name == "mon") | .port' <<< ${mon_endpoints})
+  local v2_port=$(jq '.subsets[0].ports[] | select(.name == "mon-msgr2") | .port' <<< ${mon_endpoints})
+
+  for mon in ${mon_hostnames}; do
+    local mon_endpoint=$(echo "${mon_dump}" | awk "/${mon}/{print \$2}")
+    local mon_ip=$(jq -r ".subsets[0].addresses[] | select(.nodeName == \"${mon}\") | .ip" <<< ${mon_endpoints})
+    local desired_endpoint=$(printf '[v1:%s:%s/0,v2:%s:%s/0]' ${mon_ip} ${v1_port} ${mon_ip} ${v2_port})
+
+    if [[ "${mon_endpoint}" != "${desired_endpoint}" ]]; then
+      echo "endpoint for ${mon} is ${mon_endpoint}, setting it to ${desired_endpoint}"
+      ceph mon set-addrs ${mon} ${desired_endpoint}
+    fi
+  done
+}
 
 function watch_mon_health {
+  previous_mon_count=$(get_mon_count)
   while [ true ]; do
-    echo "checking for zombie mons"
-    python3 /tmp/moncheck-reap-zombies.py || true
+    mon_count=$(get_mon_count)
+    if [[ ${mon_count} -ne ${previous_mon_count} ]]; then
+      echo "checking for zombie mons"
+      python3 /tmp/moncheck-reap-zombies.py || true
+    fi
+    previous_mon_count=${mon_count}
     echo "checking for ceph-mon msgr v2"
     check_mon_msgr2
+    echo "checking mon endpoints in monmap"
+    check_mon_addrs
     echo "sleep 30 sec"
     sleep 30
   done
diff --git a/releasenotes/notes/ceph-mon.yaml b/releasenotes/notes/ceph-mon.yaml
index e071dc960..7d4a74388 100644
--- a/releasenotes/notes/ceph-mon.yaml
+++ b/releasenotes/notes/ceph-mon.yaml
@@ -15,4 +15,5 @@ ceph-mon:
   - 0.1.12 Fix Ceph checkDNS script
   - 0.1.13 Helm 3 - Fix Job labels
   - 0.1.14 Update htk requirements
+  - 0.1.15 Prevent mon-check from removing mons when down temporarily
 ...