Add means to specify server password for redis input (influxdata#4669)

Author: glinton

plugins/inputs/redis/redis.go

@@ -18,7 +18,8 @@ import (
 )
 
 type Redis struct {
-	Servers []string
+	Servers  []string
+	Password string
 	tls.ClientConfig
 
 	clients     []Client
@@ -59,6 +60,9 @@ var sampleConfig = `
   ## If no port is specified, 6379 is used
   servers = ["tcp://localhost:6379"]
 
+  ## specify server password
+  # password = "s#cr@t%"
+
   ## Optional TLS Config
   # tls_ca = "/etc/telegraf/ca.pem"
   # tls_cert = "/etc/telegraf/cert.pem"
@@ -110,6 +114,9 @@ func (r *Redis) init(acc telegraf.Accumulator) error {
 				password = pw
 			}
 		}
+		if len(r.Password) > 0 {
+			password = r.Password
+		}
 
 		var address string
 		if u.Scheme == "unix" {