SERVER-25629 Log a warning if it looks like the operator reversed the two haves of the CSRS config string passed to --configdb.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/mongo/s/mongos_options.cpp b/src/mongo/s/mongos_options.cpp
index b2bcedb04ca..1f4a50ad9cd 100644
--- a/src/mongo/s/mongos_options.cpp
+++ b/src/mongo/s/mongos_options.cpp
@@ -45,9 +45,11 @@
 #include "mongo/s/version_mongos.h"
 #include "mongo/util/log.h"
 #include "mongo/util/mongoutils/str.h"
+#include "mongo/util/net/sock.h"
 #include "mongo/util/net/ssl_options.h"
 #include "mongo/util/options_parser/startup_options.h"
 #include "mongo/util/startup_test.h"
+#include "mongo/util/stringutils.h"
 
 namespace mongo {
 
@@ -218,11 +220,24 @@ Status storeMongosOptions(const moe::Environment& params) {
     }
 
     std::vector<HostAndPort> seedServers;
+    bool resolvedSomeSeedSever = false;
     for (const auto& host : configdbConnectionString.getValue().getServers()) {
         seedServers.push_back(host);
         if (!seedServers.back().hasPort()) {
             seedServers.back() = HostAndPort{host.host(), ServerGlobalParams::ConfigServerPort};
         }
+        if (!hostbyname(seedServers.back().host().c_str()).empty()) {
+            resolvedSomeSeedSever = true;
+        }
+    }
+    if (!resolvedSomeSeedSever) {
+        if (!hostbyname(configdbConnectionString.getValue().getSetName().c_str()).empty()) {
+            warning() << "The replica set name \""
+                      << escape(configdbConnectionString.getValue().getSetName())
+                      << "\" resolves as a host name, but none of the servers in the seed list do. "
+                         "Did you reverse the replica set name and the seed list in "
+                      << escape(configdbConnectionString.getValue().toString()) << "?";
+        }
     }
 
     mongosGlobalParams.configdbs =