Add cache stats (#69)

Author: jac

client/nginx.go

@@ -115,6 +115,7 @@ func (internalError *internalError) Wrap(err string) *internalError {
 // https://nginx.org/en/docs/http/ngx_http_api_module.html
 type Stats struct {
 	NginxInfo         NginxInfo
+	Caches            Caches
 	Processes         Processes
 	Connections       Connections
 	Slabs             Slabs
@@ -141,6 +142,36 @@ type NginxInfo struct {
 	ParentProcessID uint64 `json:"ppid"`
 }
 
+// Caches is a map of cache stats by cache zone
+type Caches = map[string]HTTPCache
+
+// HTTPCache represents a zone's HTTP Cache
+type HTTPCache struct {
+	Size        uint64
+	MaxSize     uint64 `json:"max_size"`
+	Cold        bool
+	Hit         CacheStats
+	Stale       CacheStats
+	Updating    CacheStats
+	Revalidated CacheStats
+	Miss        CacheStats
+	Expired     ExtendedCacheStats
+	Bypass      ExtendedCacheStats
+}
+
+// CacheStats are basic cache stats.
+type CacheStats struct {
+	Responses uint64
+	Bytes     uint64
+}
+
+// ExtendedCacheStats are extended cache stats.
+type ExtendedCacheStats struct {
+	CacheStats
+	ResponsesWritten uint64 `json:"responses_written"`
+	BytesWritten     uint64 `json:"bytes_written"`
+}
+
 // Connections represents connection related stats.
 type Connections struct {
 	Accepted uint64
@@ -965,6 +996,11 @@ func (client *NginxClient) GetStats() (*Stats, error) {
 		return nil, fmt.Errorf("failed to get stats: %v", err)
 	}
 
+	caches, err := client.GetCaches()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get stats: %v", err)
+	}
+
 	processes, err := client.GetProcesses()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get stats: %v", err)
@@ -1027,6 +1063,7 @@ func (client *NginxClient) GetStats() (*Stats, error) {
 
 	return &Stats{
 		NginxInfo:         *info,
+		Caches:            *caches,
 		Processes:         *processes,
 		Slabs:             *slabs,
 		Connections:       *cons,
@@ -1052,6 +1089,16 @@ func (client *NginxClient) GetNginxInfo() (*NginxInfo, error) {
 	return &info, nil
 }
 
+// GetCaches returns Cache stats
+func (client *NginxClient) GetCaches() (*Caches, error) {
+	var caches Caches
+	err := client.get("http/caches", &caches)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get caches: %v", err)
+	}
+	return &caches, nil
+}
+
 // GetSlabs returns Slabs stats.
 func (client *NginxClient) GetSlabs() (*Slabs, error) {
 	var slabs Slabs

docker/test.conf

@@ -2,6 +2,8 @@ upstream test {
     zone test 64k;
 }
 
+proxy_cache_path /var/cache/nginx keys_zone=http_cache:10m max_size=100m;
+
 server {
     listen 8080;
 
@@ -16,6 +18,7 @@ server {
 
     location /test {
         proxy_pass http://test;
+        proxy_cache http_cache;
         health_check interval=10 fails=3 passes=1;
     }
     status_zone test;

tests/client_test.go

@@ -12,6 +12,7 @@ import (
 )
 
 const (
+	cacheZone      = "http_cache"
 	upstream       = "test"
 	streamUpstream = "stream_test"
 	streamZoneSync = "zone_test_sync"
@@ -627,6 +628,14 @@ func TestStats(t *testing.T) {
 		t.Errorf("Bad connections: %v", stats.Connections)
 	}
 
+	if val, ok := stats.Caches[cacheZone]; ok {
+		if val.MaxSize != 104857600 { // 100MiB
+			t.Errorf("Cache max size stats missing: %v", val.Size)
+		}
+	} else {
+		t.Errorf("Cache stats for cache zone '%v' not found", cacheZone)
+	}
+
 	if val, ok := stats.Slabs[upstream]; ok {
 		if val.Pages.Used < 1 {
 			t.Errorf("Slabs pages stats missing: %v", val.Pages)