feat(inputs.nginx_plus_api): Gather limit_reqs metrics

plugins/inputs/nginx_plus_api/README.md

@@ -62,8 +62,9 @@ between Nginx (F/OSS) and Nginx Plus, see the Nginx [documentation][diff-doc].
 | nginx_plus_api_stream_server_zones   | >= 3                      |
 | nginx_plus_api_http_location_zones   | >= 5                      |
 | nginx_plus_api_resolver_zones        | >= 5                      |
+| nginx_plus_api_http_limit_reqs       | >= 6                      |
 
-## Measurements & Fields
+## Metrics
 
 - nginx_plus_api_processes
   - respawned
@@ -194,8 +195,14 @@ between Nginx (F/OSS) and Nginx Plus, see the Nginx [documentation][diff-doc].
   - refused
   - timedout
   - unknown
+- nginx_plus_api_http_limit_reqs
+  - passed
+  - delayed
+  - rejected
+  - delayed_dry_run
+  - rejected_dry_run
 
-## Tags
+### Tags
 
 - nginx_plus_api_processes, nginx_plus_api_connections, nginx_plus_api_ssl, nginx_plus_api_http_requests
   - source
@@ -228,6 +235,11 @@ between Nginx (F/OSS) and Nginx Plus, see the Nginx [documentation][diff-doc].
   - source
   - port
 
+- nginx_plus_api_http_limit_reqs
+  - source
+  - port
+  - limit
+
 ## Example Output
 
 Using this configuration:
@@ -287,8 +299,11 @@ It produces:
 > nginx_plus_api_http_location_zones,port=80,source=demo.nginx.com,zone=swagger discarded=0i,received=1622i,requests=8i,responses_1xx=0i,responses_2xx=7i,responses_3xx=0i,responses_4xx=1i,responses_5xx=0i,responses_total=8i,sent=638333i 1570696323000000000
 > nginx_plus_api_http_location_zones,port=80,source=demo.nginx.com,zone=api-calls discarded=64i,received=337530181i,requests=1726513i,responses_1xx=0i,responses_2xx=1726428i,responses_3xx=0i,responses_4xx=21i,responses_5xx=0i,responses_total=1726449i,sent=1902577668i 1570696323000000000
 > nginx_plus_api_resolver_zones,port=80,source=demo.nginx.com,zone=resolver1 addr=0i,formerr=0i,name=0i,noerror=0i,notimp=0i,nxdomain=0i,refused=0i,servfail=0i,srv=0i,timedout=0i,unknown=0i 1570696324000000000
+> nginx_plus_api_http_limit_reqs,port=80,source=demo.nginx.com,limit=limit_1 delayed=0i,delayed_dry_run=0i,passed=6i,rejected=9i,rejected_dry_run=0i 1570696322000000000
+> nginx_plus_api_http_limit_reqs,port=80,source=demo.nginx.com,limit=limit_2 delayed=13i,delayed_dry_run=3i,passed=6i,rejected=1i,rejected_dry_run=31i 1570696322000000000
 ```
 
 ### Reference material
 
-[api documentation](http://demo.nginx.com/swagger-ui/#/)
+- [api documentation](http://demo.nginx.com/swagger-ui/#/)
+- [nginx_api_module documentation](http://nginx.org/en/docs/http/ngx_http_api_module.html)

plugins/inputs/nginx_plus_api/nginx_plus_api.go

@@ -43,8 +43,8 @@ const (
 	httpLocationZonesPath = "http/location_zones"
 	httpUpstreamsPath     = "http/upstreams"
 	httpCachesPath        = "http/caches"
-
-	resolverZonesPath = "resolvers"
+	httpLimitReqsPath     = "http/limit_reqs"
+	resolverZonesPath     = "resolvers"
 
 	streamServerZonesPath = "stream/server_zones"
 	streamUpstreamsPath   = "stream/upstreams"

plugins/inputs/nginx_plus_api/nginx_plus_api_metrics.go

@@ -35,6 +35,9 @@ func (n *NginxPlusAPI) gatherMetrics(addr *url.URL, acc telegraf.Accumulator) {
 		addError(acc, n.gatherHTTPLocationZonesMetrics(addr, acc))
 		addError(acc, n.gatherResolverZonesMetrics(addr, acc))
 	}
+	if n.APIVersion >= 6 {
+		addError(acc, n.gatherHTTPLimitReqsMetrics(addr, acc))
+	}
 }
 
 func addError(acc telegraf.Accumulator, err error) {
@@ -613,6 +616,43 @@ func (n *NginxPlusAPI) gatherStreamUpstreamsMetrics(addr *url.URL, acc telegraf.
 	return nil
 }
 
+// Added in 6 API version
+func (n *NginxPlusAPI) gatherHTTPLimitReqsMetrics(addr *url.URL, acc telegraf.Accumulator) error {
+	body, err := n.gatherURL(addr, httpLimitReqsPath)
+	if err != nil {
+		return err
+	}
+
+	var httpLimitReqs HTTPLimitReqs
+
+	if err := json.Unmarshal(body, &httpLimitReqs); err != nil {
+		return err
+	}
+
+	tags := getTags(addr)
+
+	for limitReqName, limit := range httpLimitReqs {
+		limitReqsTags := map[string]string{}
+		for k, v := range tags {
+			limitReqsTags[k] = v
+		}
+		limitReqsTags["limit"] = limitReqName
+		acc.AddFields(
+			"nginx_plus_api_http_limit_reqs",
+			map[string]interface{}{
+				"passed":           limit.Passed,
+				"delayed":          limit.Delayed,
+				"rejected":         limit.Rejected,
+				"delayed_dry_run":  limit.DelayedDryRun,
+				"rejected_dry_run": limit.RejectedDryRun,
+			},
+			limitReqsTags,
+		)
+	}
+
+	return nil
+}
+
 func getTags(addr *url.URL) map[string]string {
 	h := addr.Host
 	host, port, err := net.SplitHostPort(h)

plugins/inputs/nginx_plus_api/nginx_plus_api_metrics_test.go

@@ -245,6 +245,25 @@ const httpServerZonesPayload = `
 }
 `
 
+const httpLimitReqsPayload = `
+{
+        "limit_1": {
+                "passed": 2,
+                "delayed": 9,
+                "rejected": 4,
+                "delayed_dry_run": 100,
+                "rejected_dry_run": 330
+        },
+        "limit_2": {
+                "passed": 451,
+                "delayed": 10,
+                "rejected": 0,
+                "delayed_dry_run": 10,
+                "rejected_dry_run": 32
+        }
+}
+`
+
 const httpLocationZonesPayload = `
 {
   "site1": {
@@ -857,6 +876,48 @@ func TestGatherHttpServerZonesMetrics(t *testing.T) {
 		})
 }
 
+func TestGatherHttpLimitReqsMetrics(t *testing.T) {
+	ts, n := prepareEndpoint(t, httpLimitReqsPath, httpLimitReqsPayload)
+	defer ts.Close()
+
+	var acc testutil.Accumulator
+	addr, host, port := prepareAddr(t, ts)
+
+	require.NoError(t, n.gatherHTTPLimitReqsMetrics(addr, &acc))
+
+	acc.AssertContainsTaggedFields(
+		t,
+		"nginx_plus_api_http_limit_reqs",
+		map[string]interface{}{
+			"passed":           int64(2),
+			"delayed":          int64(9),
+			"rejected":         int64(4),
+			"delayed_dry_run":  int64(100),
+			"rejected_dry_run": int64(330),
+		},
+		map[string]string{
+			"source": host,
+			"port":   port,
+			"limit":  "limit_1",
+		})
+
+	acc.AssertContainsTaggedFields(
+		t,
+		"nginx_plus_api_http_limit_reqs",
+		map[string]interface{}{
+			"passed":           int64(451),
+			"delayed":          int64(10),
+			"rejected":         int64(0),
+			"delayed_dry_run":  int64(10),
+			"rejected_dry_run": int64(32),
+		},
+		map[string]string{
+			"source": host,
+			"port":   port,
+			"limit":  "limit_2",
+		})
+}
+
 func TestGatherHttpLocationZonesMetrics(t *testing.T) {
 	ts, n := prepareEndpoint(t, httpLocationZonesPath, httpLocationZonesPayload)
 	defer ts.Close()

plugins/inputs/nginx_plus_api/nginx_plus_api_types.go

@@ -170,3 +170,11 @@ type HTTPCaches map[string]struct { // added in version 2
 	Expired     ExtendedHitStats `json:"expired"`
 	Bypass      ExtendedHitStats `json:"bypass"`
 }
+
+type HTTPLimitReqs map[string]struct {
+	Passed         int64 `json:"passed"`
+	Delayed        int64 `json:"delayed"`
+	Rejected       int64 `json:"rejected"`
+	DelayedDryRun  int64 `json:"delayed_dry_run"`
+	RejectedDryRun int64 `json:"rejected_dry_run"`
+}