Update default value for Cloudwatch rate limit (#2520)

plugins/inputs/cloudwatch/README.md

@@ -42,9 +42,10 @@ API endpoint. In the following order the plugin will attempt to authenticate.
   namespace = "AWS/ELB"
 
   ## Maximum requests per second. Note that the global default AWS rate limit is
-  ## 10 reqs/sec, so if you define multiple namespaces, these should add up to a
-  ## maximum of 10. Optional - default value is 10.
-  ratelimit = 10
+  ## 400 reqs/sec, so if you define multiple namespaces, these should add up to a
+  ## maximum of 400. Optional - default value is 200.
+  ## See http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch_limits.html
+  ratelimit = 200
 
   ## Metrics to Pull (optional)
   ## Defaults to all Metrics in Namespace if nothing is provided

plugins/inputs/cloudwatch/cloudwatch.go

@@ -105,9 +105,10 @@ func (c *CloudWatch) SampleConfig() string {
   namespace = "AWS/ELB"
 
   ## Maximum requests per second. Note that the global default AWS rate limit is
-  ## 10 reqs/sec, so if you define multiple namespaces, these should add up to a
-  ## maximum of 10. Optional - default value is 10.
-  ratelimit = 10
+  ## 400 reqs/sec, so if you define multiple namespaces, these should add up to a
+  ## maximum of 400. Optional - default value is 200.
+  ## See http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch_limits.html
+  ratelimit = 200
 
   ## Metrics to Pull (optional)
   ## Defaults to all Metrics in Namespace if nothing is provided
@@ -214,7 +215,7 @@ func init() {
 		ttl, _ := time.ParseDuration("1hr")
 		return &CloudWatch{
 			CacheTTL:  internal.Duration{Duration: ttl},
-			RateLimit: 10,
+			RateLimit: 200,
 		}
 	})
 }

plugins/inputs/cloudwatch/cloudwatch_test.go

@@ -58,7 +58,7 @@ func TestGather(t *testing.T) {
 		Namespace: "AWS/ELB",
 		Delay:     internalDuration,
 		Period:    internalDuration,
-		RateLimit: 10,
+		RateLimit: 200,
 	}
 
 	var acc testutil.Accumulator
@@ -146,7 +146,7 @@ func TestSelectMetrics(t *testing.T) {
 		Namespace: "AWS/ELB",
 		Delay:     internalDuration,
 		Period:    internalDuration,
-		RateLimit: 10,
+		RateLimit: 200,
 		Metrics: []*Metric{
 			&Metric{
 				MetricNames: []string{"Latency", "RequestCount"},