diff --git a/agent/agent.go b/agent/agent.go
index 700bccb05..e2ef79b84 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -210,7 +210,7 @@ func (a *Agent) Test(ctx context.Context, waitDuration time.Duration) error {
 		// Special instructions for some inputs. cpu, for example, needs to be
 		// run twice in order to return cpu usage percentages.
 		switch input.Config.Name {
-		case "inputs.cpu", "inputs.mongodb", "inputs.procstat":
+		case "cpu", "mongodb", "procstat":
 			nulAcc := NewAccumulator(input, nulC)
 			nulAcc.SetPrecision(a.Precision())
 			if err := input.Input.Gather(nulAcc); err != nil {
diff --git a/plugins/inputs/mongodb/mongodb_data.go b/plugins/inputs/mongodb/mongodb_data.go
index c218fd3ad..6f999cbd7 100644
--- a/plugins/inputs/mongodb/mongodb_data.go
+++ b/plugins/inputs/mongodb/mongodb_data.go
@@ -101,7 +101,6 @@ var DefaultReplStats = map[string]string{
 	"member_status":         "NodeType",
 	"state":                 "NodeState",
 	"repl_lag":              "ReplLag",
-	"repl_oplog_window_sec": "OplogTimeDiff",
 }
 
 var DefaultClusterStats = map[string]string{
@@ -230,6 +229,11 @@ func (d *MongodbData) AddDefaultStats() {
 	if d.StatLine.NodeType != "" {
 		d.addStat(statLine, DefaultReplStats)
 	}
+
+	if d.StatLine.OplogStats != nil {
+		d.add("repl_oplog_window_sec", d.StatLine.OplogStats.TimeDiff)
+	}
+
 	d.addStat(statLine, DefaultClusterStats)
 	d.addStat(statLine, DefaultShardStats)
 	if d.StatLine.StorageEngine == "mmapv1" || d.StatLine.StorageEngine == "rocksdb" {
diff --git a/plugins/inputs/mongodb/mongodb_data_test.go b/plugins/inputs/mongodb/mongodb_data_test.go
index da50bdc9e..527e7ab93 100644
--- a/plugins/inputs/mongodb/mongodb_data_test.go
+++ b/plugins/inputs/mongodb/mongodb_data_test.go
@@ -232,7 +232,6 @@ func TestStateTag(t *testing.T) {
 		"repl_updates":              int64(0),
 		"repl_updates_per_sec":      int64(0),
 		"repl_lag":                  int64(0),
-		"repl_oplog_window_sec":     int64(0),
 		"resident_megabytes":        int64(0),
 		"updates":                   int64(0),
 		"updates_per_sec":           int64(0),
diff --git a/plugins/inputs/mongodb/mongodb_server.go b/plugins/inputs/mongodb/mongodb_server.go
index 4df14c014..404fa8143 100644
--- a/plugins/inputs/mongodb/mongodb_server.go
+++ b/plugins/inputs/mongodb/mongodb_server.go
@@ -39,35 +39,116 @@ func authLogLevel(err error) string {
 	}
 }
 
-func (s *Server) gatherOplogStats() *OplogStats {
-	stats := &OplogStats{}
-	localdb := s.Session.DB("local")
+func (s *Server) gatherServerStatus() (*ServerStatus, error) {
+	serverStatus := &ServerStatus{}
+	err := s.Session.DB("admin").Run(bson.D{
+		{
+			Name:  "serverStatus",
+			Value: 1,
+		},
+		{
+			Name:  "recordStats",
+			Value: 0,
+		},
+	}, serverStatus)
+	if err != nil {
+		return nil, err
+	}
+	return serverStatus, nil
+}
 
-	op_first := oplogEntry{}
-	op_last := oplogEntry{}
-	query := bson.M{"ts": bson.M{"$exists": true}}
+func (s *Server) gatherReplSetStatus() (*ReplSetStatus, error) {
+	replSetStatus := &ReplSetStatus{}
+	err := s.Session.DB("admin").Run(bson.D{
+		{
+			Name:  "replSetGetStatus",
+			Value: 1,
+		},
+	}, replSetStatus)
+	if err != nil {
+		return nil, err
+	}
+	return replSetStatus, nil
+}
 
-	for _, collection_name := range []string{"oplog.rs", "oplog.$main"} {
-		if err := localdb.C(collection_name).Find(query).Sort("$natural").Limit(1).One(&op_first); err != nil {
-			if err == mgo.ErrNotFound {
-				continue
-			}
-			log.Printf("%s [inputs.mongodb] Error getting first oplog entry: %v", authLogLevel(err), err)
-			return stats
-		}
-		if err := localdb.C(collection_name).Find(query).Sort("-$natural").Limit(1).One(&op_last); err != nil {
-			if err == mgo.ErrNotFound || IsAuthorization(err) {
-				continue
-			}
-			log.Printf("%s [inputs.mongodb] Error getting first oplog entry: %v", authLogLevel(err), err)
-			return stats
-		}
+func (s *Server) gatherClusterStatus() (*ClusterStatus, error) {
+	chunkCount, err := s.Session.DB("config").C("chunks").Find(bson.M{"jumbo": true}).Count()
+	if err != nil {
+		return nil, err
 	}
 
-	op_first_time := time.Unix(int64(op_first.Timestamp>>32), 0)
-	op_last_time := time.Unix(int64(op_last.Timestamp>>32), 0)
-	stats.TimeDiff = int64(op_last_time.Sub(op_first_time).Seconds())
-	return stats
+	return &ClusterStatus{
+		JumboChunksCount: int64(chunkCount),
+	}, nil
+}
+
+func (s *Server) gatherShardConnPoolStats() (*ShardStats, error) {
+	shardStats := &ShardStats{}
+	err := s.Session.DB("admin").Run(bson.D{
+		{
+			Name:  "shardConnPoolStats",
+			Value: 1,
+		},
+	}, &shardStats)
+	if err != nil {
+		return nil, err
+	}
+	return shardStats, nil
+}
+
+func (s *Server) gatherDBStats(name string) (*Db, error) {
+	stats := &DbStatsData{}
+	err := s.Session.DB(name).Run(bson.D{
+		{
+			Name:  "dbStats",
+			Value: 1,
+		},
+	}, stats)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Db{
+		Name:        name,
+		DbStatsData: stats,
+	}, nil
+}
+
+func (s *Server) getOplogReplLag(collection string) (*OplogStats, error) {
+	query := bson.M{"ts": bson.M{"$exists": true}}
+
+	var first oplogEntry
+	err := s.Session.DB("local").C(collection).Find(query).Sort("$natural").Limit(1).One(&first)
+	if err != nil {
+		return nil, err
+	}
+
+	var last oplogEntry
+	err = s.Session.DB("local").C(collection).Find(query).Sort("-$natural").Limit(1).One(&last)
+	if err != nil {
+		return nil, err
+	}
+
+	firstTime := time.Unix(int64(first.Timestamp>>32), 0)
+	lastTime := time.Unix(int64(last.Timestamp>>32), 0)
+	stats := &OplogStats{
+		TimeDiff: int64(lastTime.Sub(firstTime).Seconds()),
+	}
+	return stats, nil
+}
+
+// The "oplog.rs" collection is stored on all replica set members.
+//
+// The "oplog.$main" collection is created on the master node of a
+// master-slave replicated deployment.  As of MongoDB 3.2, master-slave
+// replication has been deprecated.
+func (s *Server) gatherOplogStats() (*OplogStats, error) {
+	stats, err := s.getOplogReplLag("oplog.rs")
+	if err == nil {
+		return stats, nil
+	}
+
+	return s.getOplogReplLag("oplog.$main")
 }
 
 func (s *Server) gatherCollectionStats(colStatsDbs []string) (*ColStats, error) {
@@ -112,99 +193,71 @@ func (s *Server) gatherCollectionStats(colStatsDbs []string) (*ColStats, error)
 func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool, gatherColStats bool, colStatsDbs []string) error {
 	s.Session.SetMode(mgo.Eventual, true)
 	s.Session.SetSocketTimeout(0)
-	result_server := &ServerStatus{}
-	err := s.Session.DB("admin").Run(bson.D{
-		{
-			Name:  "serverStatus",
-			Value: 1,
-		},
-		{
-			Name:  "recordStats",
-			Value: 0,
-		},
-	}, result_server)
+
+	serverStatus, err := s.gatherServerStatus()
 	if err != nil {
 		return err
 	}
-	result_repl := &ReplSetStatus{}
-	// ignore error because it simply indicates that the db is not a member
-	// in a replica set, which is fine.
-	_ = s.Session.DB("admin").Run(bson.D{
-		{
-			Name:  "replSetGetStatus",
-			Value: 1,
-		},
-	}, result_repl)
 
-	jumbo_chunks, _ := s.Session.DB("config").C("chunks").Find(bson.M{"jumbo": true}).Count()
-
-	result_cluster := &ClusterStatus{
-		JumboChunksCount: int64(jumbo_chunks),
-	}
-
-	resultShards := &ShardStats{}
-	err = s.Session.DB("admin").Run(bson.D{
-		{
-			Name:  "shardConnPoolStats",
-			Value: 1,
-		},
-	}, &resultShards)
+	// Get replica set status, an error indicates that the server is not a
+	// member of a replica set.
+	replSetStatus, err := s.gatherReplSetStatus()
 	if err != nil {
-		if IsAuthorization(err) {
-			log.Printf("D! [inputs.mongodb] Error getting database shard stats: %v", err)
-		} else {
-			log.Printf("E! [inputs.mongodb] Error getting database shard stats: %v", err)
-		}
+		log.Printf("D! [inputs.mongodb] Unable to gather replica set status: %v", err)
 	}
 
-	oplogStats := s.gatherOplogStats()
-
-	result_db_stats := &DbStats{}
-	if gatherDbStats == true {
-		names := []string{}
-		names, err = s.Session.DatabaseNames()
+	// Gather the oplog if we are a member of a replica set.  Non-replica set
+	// members do not have the oplog collections.
+	var oplogStats *OplogStats
+	if replSetStatus != nil {
+		oplogStats, err = s.gatherOplogStats()
 		if err != nil {
-			log.Printf("E! [inputs.mongodb] Error getting database names: %v", err)
-		}
-		for _, db_name := range names {
-			db_stat_line := &DbStatsData{}
-			err = s.Session.DB(db_name).Run(bson.D{
-				{
-					Name:  "dbStats",
-					Value: 1,
-				},
-			}, db_stat_line)
-			if err != nil {
-				log.Printf("E! [inputs.mongodb] Error getting db stats from %q: %v", db_name, err)
-			}
-			db := &Db{
-				Name:        db_name,
-				DbStatsData: db_stat_line,
-			}
-
-			result_db_stats.Dbs = append(result_db_stats.Dbs, *db)
+			return err
 		}
 	}
 
-	result_col_stats, err := s.gatherCollectionStats(colStatsDbs)
+	clusterStatus, err := s.gatherClusterStatus()
+	if err != nil {
+		log.Printf("D! [inputs.mongodb] Unable to gather cluster status: %v", err)
+	}
+
+	shardStats, err := s.gatherShardConnPoolStats()
+	if err != nil {
+		log.Printf("%s [inputs.mongodb] Unable to gather shard connection pool stats: %v",
+			authLogLevel(err), err)
+	}
+
+	collectionStats, err := s.gatherCollectionStats(colStatsDbs)
 	if err != nil {
 		return err
 	}
 
+	dbStats := &DbStats{}
+	if gatherDbStats {
+		names, err := s.Session.DatabaseNames()
+		if err != nil {
+			return err
+		}
+
+		for _, name := range names {
+			db, err := s.gatherDBStats(name)
+			if err != nil {
+				log.Printf("D! [inputs.mongodb] Error getting db stats from %q: %v", name, err)
+			}
+			dbStats.Dbs = append(dbStats.Dbs, *db)
+		}
+	}
+
 	result := &MongoStatus{
-		ServerStatus:  result_server,
-		ReplSetStatus: result_repl,
-		ClusterStatus: result_cluster,
-		DbStats:       result_db_stats,
-		ColStats:      result_col_stats,
-		ShardStats:    resultShards,
+		ServerStatus:  serverStatus,
+		ReplSetStatus: replSetStatus,
+		ClusterStatus: clusterStatus,
+		DbStats:       dbStats,
+		ColStats:      collectionStats,
+		ShardStats:    shardStats,
 		OplogStats:    oplogStats,
 	}
 
-	defer func() {
-		s.lastResult = result
-	}()
-
 	result.SampleTime = time.Now()
 	if s.lastResult != nil && result != nil {
 		duration := result.SampleTime.Sub(s.lastResult.SampleTime)
@@ -222,6 +275,8 @@ func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool, gather
 		data.AddShardHostStats()
 		data.flush(acc)
 	}
+
+	s.lastResult = result
 	return nil
 }
 
diff --git a/plugins/inputs/mongodb/mongostat.go b/plugins/inputs/mongodb/mongostat.go
index 709c074d7..d82100974 100644
--- a/plugins/inputs/mongodb/mongostat.go
+++ b/plugins/inputs/mongodb/mongostat.go
@@ -541,7 +541,7 @@ type StatLine struct {
 	GetMoreR, GetMoreRCnt                int64
 	CommandR, CommandRCnt                int64
 	ReplLag                              int64
-	OplogTimeDiff                        int64
+	OplogStats                           *OplogStats
 	Flushes, FlushesCnt                  int64
 	FlushesTotalTime                     int64
 	Mapped, Virtual, Resident, NonMapped int64
@@ -890,66 +890,75 @@ func NewStatLine(oldMongo, newMongo MongoStatus, key string, all bool, sampleSec
 		returnVal.NumConnections = newStat.Connections.Current
 	}
 
-	newReplStat := *newMongo.ReplSetStatus
+	if newMongo.ReplSetStatus != nil {
+		newReplStat := *newMongo.ReplSetStatus
 
-	if newReplStat.Members != nil {
-		myName := newStat.Repl.Me
-		// Find the master and myself
-		master := ReplSetMember{}
-		me := ReplSetMember{}
-		for _, member := range newReplStat.Members {
-			if member.Name == myName {
-				// Store my state string
-				returnVal.NodeState = member.StateStr
-				if member.State == 1 {
-					// I'm the master
-					returnVal.ReplLag = 0
-					break
-				} else {
-					// I'm secondary
-					me = member
+		if newReplStat.Members != nil {
+			myName := newStat.Repl.Me
+			// Find the master and myself
+			master := ReplSetMember{}
+			me := ReplSetMember{}
+			for _, member := range newReplStat.Members {
+				if member.Name == myName {
+					// Store my state string
+					returnVal.NodeState = member.StateStr
+					if member.State == 1 {
+						// I'm the master
+						returnVal.ReplLag = 0
+						break
+					} else {
+						// I'm secondary
+						me = member
+					}
+				} else if member.State == 1 {
+					// Master found
+					master = member
 				}
-			} else if member.State == 1 {
-				// Master found
-				master = member
 			}
-		}
 
-		if me.State == 2 {
-			// OptimeDate.Unix() type is int64
-			lag := master.OptimeDate.Unix() - me.OptimeDate.Unix()
-			if lag < 0 {
-				returnVal.ReplLag = 0
-			} else {
-				returnVal.ReplLag = lag
+			if me.State == 2 {
+				// OptimeDate.Unix() type is int64
+				lag := master.OptimeDate.Unix() - me.OptimeDate.Unix()
+				if lag < 0 {
+					returnVal.ReplLag = 0
+				} else {
+					returnVal.ReplLag = lag
+				}
 			}
 		}
 	}
 
-	newClusterStat := *newMongo.ClusterStatus
-	returnVal.JumboChunksCount = newClusterStat.JumboChunksCount
-	returnVal.OplogTimeDiff = newMongo.OplogStats.TimeDiff
+	if newMongo.ClusterStatus != nil {
+		newClusterStat := *newMongo.ClusterStatus
+		returnVal.JumboChunksCount = newClusterStat.JumboChunksCount
+	}
 
-	newDbStats := *newMongo.DbStats
-	for _, db := range newDbStats.Dbs {
-		dbStatsData := db.DbStatsData
-		// mongos doesn't have the db key, so setting the db name
-		if dbStatsData.Db == "" {
-			dbStatsData.Db = db.Name
+	if newMongo.OplogStats != nil {
+		returnVal.OplogStats = newMongo.OplogStats
+	}
+
+	if newMongo.DbStats != nil {
+		newDbStats := *newMongo.DbStats
+		for _, db := range newDbStats.Dbs {
+			dbStatsData := db.DbStatsData
+			// mongos doesn't have the db key, so setting the db name
+			if dbStatsData.Db == "" {
+				dbStatsData.Db = db.Name
+			}
+			dbStatLine := &DbStatLine{
+				Name:        dbStatsData.Db,
+				Collections: dbStatsData.Collections,
+				Objects:     dbStatsData.Objects,
+				AvgObjSize:  dbStatsData.AvgObjSize,
+				DataSize:    dbStatsData.DataSize,
+				StorageSize: dbStatsData.StorageSize,
+				NumExtents:  dbStatsData.NumExtents,
+				Indexes:     dbStatsData.Indexes,
+				IndexSize:   dbStatsData.IndexSize,
+				Ok:          dbStatsData.Ok,
+			}
+			returnVal.DbStatsLines = append(returnVal.DbStatsLines, *dbStatLine)
 		}
-		dbStatLine := &DbStatLine{
-			Name:        dbStatsData.Db,
-			Collections: dbStatsData.Collections,
-			Objects:     dbStatsData.Objects,
-			AvgObjSize:  dbStatsData.AvgObjSize,
-			DataSize:    dbStatsData.DataSize,
-			StorageSize: dbStatsData.StorageSize,
-			NumExtents:  dbStatsData.NumExtents,
-			Indexes:     dbStatsData.Indexes,
-			IndexSize:   dbStatsData.IndexSize,
-			Ok:          dbStatsData.Ok,
-		}
-		returnVal.DbStatsLines = append(returnVal.DbStatsLines, *dbStatLine)
 	}
 
 	newColStats := *newMongo.ColStats