From d0192e59623f0ad06496f7ddfd647c028607c665 Mon Sep 17 00:00:00 2001
From: John Spray <john.spray@redhat.com>
Date: Sun, 16 Jul 2017 12:08:32 -0400
Subject: [PATCH] mds: revise health checks for _FAILED/_DEGRADED

No longer output MDS_* versions as well as FS_* versions,
because it was noisy and the important message is about
the availability (or not) of the filesystem.

Revise the _FAILED check to only raise the message if
there are not suitable replacements available for failed
ranks.  This avoids a spurious health check failure when
a rank has been failed (e.g. by the admin) but it will
be replaced at the next tick().

After this change, doing a "ceph mds fail" when a standby
is available just gives you a single FS_DEGRADED health
check from the point of the "fail" to when the replacement
is active.

Signed-off-by: John Spray <john.spray@redhat.com>
---
 src/mds/FSMap.cc  | 27 +++++++++++++++++++++++++++
 src/mds/MDSMap.cc | 27 ---------------------------
 2 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/src/mds/FSMap.cc b/src/mds/FSMap.cc
index 10abd5d2c0d..f44eadf3c3f 100644
--- a/src/mds/FSMap.cc
+++ b/src/mds/FSMap.cc
@@ -341,7 +341,34 @@ void FSMap::get_health_checks(health_check_map_t *checks) const
   for (const auto &i : filesystems) {
     const auto &fs = i.second;
     health_check_map_t fschecks;
+
     fs->mds_map.get_health_checks(&fschecks);
+
+    // Some of the failed ranks might be transient (i.e. there are standbys
+    // ready to replace them).  We will report only on "stuck" failed, i.e.
+    // ranks which are failed and have no standby replacement available.
+    std::set<mds_rank_t> stuck_failed;
+
+    for (const auto &rank : fs->mds_map.failed) {
+      const mds_gid_t replacement = find_replacement_for(
+          {fs->fscid, rank}, {}, g_conf->mon_force_standby_active);
+      if (replacement == MDS_GID_NONE) {
+        stuck_failed.insert(rank);
+      }
+    }
+
+    // FS_WITH_FAILED_MDS
+    // MDS_FAILED
+    if (!stuck_failed.empty()) {
+      health_check_t& fscheck = checks->add(
+        "FS_WITH_FAILED_MDS", HEALTH_WARN,
+        "%num% filesystem%plurals% %isorare% have a failed mds daemon");
+      ostringstream ss;
+      ss << "fs " << fs->mds_map.fs_name << " has " << stuck_failed.size()
+         << " failed mds" << (stuck_failed.size() > 1 ? "s" : "");
+      fscheck.detail.push_back(ss.str());
+    }
+
     checks->merge(fschecks);
     standby_count_wanted = std::max(
       standby_count_wanted,
diff --git a/src/mds/MDSMap.cc b/src/mds/MDSMap.cc
index bd54469756f..e53338f656f 100644
--- a/src/mds/MDSMap.cc
+++ b/src/mds/MDSMap.cc
@@ -408,26 +408,6 @@ void MDSMap::get_health(list<pair<health_status_t,string> >& summary,
 
 void MDSMap::get_health_checks(health_check_map_t *checks) const
 {
-  // FS_WITH_FAILED_MDS
-  // MDS_FAILED
-  if (!failed.empty()) {
-    health_check_t& fscheck = checks->add(
-      "FS_WITH_FAILED_MDS", HEALTH_WARN,
-      "%num% filesystem%plurals% %isorare% have a failed mds daemon");
-    ostringstream ss;
-    ss << "fs " << fs_name << " has " << failed.size() << " failed mds"
-       << (failed.size() > 1 ? "s" : "");
-    fscheck.detail.push_back(ss.str());
-
-    health_check_t& check = checks->add("MDS_FAILED", HEALTH_ERR,
-					 "%num% mds daemon%plurals% down");
-    for (auto p : failed) {
-      std::ostringstream oss;
-      oss << "fs " << fs_name << " mds." << p << " has failed";
-      check.detail.push_back(oss.str());
-    }
-  }
-
   // MDS_DAMAGED
   if (!damaged.empty()) {
     health_check_t& check = checks->add("MDS_DAMAGED", HEALTH_ERR,
@@ -440,7 +420,6 @@ void MDSMap::get_health_checks(health_check_map_t *checks) const
   }
 
   // FS_DEGRADED
-  // MDS_DEGRADED
   if (is_degraded()) {
     health_check_t& fscheck = checks->add(
       "FS_DEGRADED", HEALTH_WARN,
@@ -469,12 +448,6 @@ void MDSMap::get_health_checks(health_check_map_t *checks) const
       if (ss.str().length())
 	detail.push_back(ss.str());
     }
-    if (!detail.empty()) {
-      health_check_t& check = checks->add(
-	"MDS_DEGRADED", HEALTH_WARN,
-	"%num% mds daemon%plurals% %isorare% degraded");
-      check.detail.insert(check.detail.end(), detail.begin(), detail.end());
-    }
   }
 }