refactor: Rename confusing metric to reference_api

cmd/root.go

@@ -60,7 +60,7 @@ func Execute() {
 	registry.MustRegister(metrics.BuildStatic(cfg.Static.Gauges)...)
 
 	// Register reference rpc metrics
-	refMets := metrics.NewReferenceRPC()
+	refMets := metrics.NewHTTPRequest()
 	registry.MustRegister(refMets.Metrics()...)
 
 	// Register cosmos chain metrics
@@ -125,7 +125,7 @@ func logFatal(msg string, err error) {
 	os.Exit(1)
 }
 
-func buildCosmosJobs(cosmosMets *metrics.Cosmos, refMets *metrics.ReferenceRPC, cfg Config) (jobs []metrics.Job) {
+func buildCosmosJobs(cosmosMets *metrics.Cosmos, refMets *metrics.ReferenceAPI, cfg Config) (jobs []metrics.Job) {
 	// TODO(nix): Need different rest clients per chain. This hack prevents > 1 chain.
 	var urls []url.URL
 	for _, rest := range cfg.Cosmos[0].Rest {
@@ -136,8 +136,7 @@ func buildCosmosJobs(cosmosMets *metrics.Cosmos, refMets *metrics.ReferenceRPC,
 		urls = append(urls, *u)
 	}
 
-	const rpcType = "cosmos"
-	restClient := cosmos.NewRestClient(metrics.NewFallbackClient(httpClient, refMets, rpcType, urls))
+	restClient := cosmos.NewRestClient(metrics.NewFallbackClient(httpClient, refMets, urls))
 
 	restJobs := cosmos.BuildRestJobs(cosmosMets, restClient, cfg.Cosmos)
 	jobs = append(jobs, toJobs(restJobs)...)

metrics/fallback_client.go

@@ -16,15 +16,14 @@ type FallbackClient struct {
 	httpDo  func(req *http.Request) (*http.Response, error)
 	log     *slog.Logger
 	metrics ClientMetrics
-	rpcType string
 }
 
 type ClientMetrics interface {
-	IncClientError(rpcType string, host url.URL, reason string)
+	IncAPIError(host url.URL, reason string)
 	// TODO(nix): Metrics for request counts. Latency histogram.
 }
 
-func NewFallbackClient(client *http.Client, metrics ClientMetrics, rpcType string, hosts []url.URL) *FallbackClient {
+func NewFallbackClient(client *http.Client, metrics ClientMetrics, hosts []url.URL) *FallbackClient {
 	if len(hosts) == 0 {
 		panic("no hosts provided")
 	}
@@ -33,15 +32,14 @@ func NewFallbackClient(client *http.Client, metrics ClientMetrics, rpcType strin
 		httpDo:  client.Do,
 		log:     slog.Default(),
 		metrics: metrics,
-		rpcType: rpcType,
 	}
 }
 
 const unknownErrReason = "unknown"
 
 func (c FallbackClient) Get(ctx context.Context, path string) (*http.Response, error) {
 	doGet := func(host url.URL) (*http.Response, error) {
-		log := c.log.With("host", host.Hostname(), "path", path, "rpc", c.rpcType)
+		log := c.log.With("host", host.Hostname(), "path", path, "method", http.MethodGet)
 		host.Path = path
 		req, err := http.NewRequestWithContext(ctx, http.MethodGet, host.String(), nil)
 		if err != nil {
@@ -58,7 +56,7 @@ func (c FallbackClient) Get(ctx context.Context, path string) (*http.Response, e
 		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
 			_ = resp.Body.Close()
 			log.Error("Response returned bad status code", "status", resp.StatusCode)
-			c.metrics.IncClientError(c.rpcType, host, strconv.Itoa(resp.StatusCode))
+			c.metrics.IncAPIError(host, strconv.Itoa(resp.StatusCode))
 			return nil, fmt.Errorf("%s: bad status code %d", req.URL, resp.StatusCode)
 		}
 		return resp, nil
@@ -85,5 +83,5 @@ func (c FallbackClient) recordErrMetric(host url.URL, err error) {
 		// Do not record when the process is shutting down.
 		return
 	}
-	c.metrics.IncClientError(c.rpcType, host, reason)
+	c.metrics.IncAPIError(host, reason)
 }

metrics/fallback_client_test.go

@@ -17,14 +17,12 @@ import (
 
 type mockClientMetrics struct {
 	IncClientErrCalls int
-	GotRPCType        string
 	GotHost           url.URL
 	GotErrMsg         string
 }
 
-func (m *mockClientMetrics) IncClientError(rpcType string, host url.URL, errMsg string) {
+func (m *mockClientMetrics) IncAPIError(host url.URL, errMsg string) {
 	m.IncClientErrCalls++
-	m.GotRPCType = rpcType
 	m.GotHost = host
 	m.GotErrMsg = errMsg
 }
@@ -41,7 +39,7 @@ func TestFallbackClient_Get(t *testing.T) {
 	ctx := context.WithValue(context.Background(), dummy("test"), dummy("test"))
 
 	t.Run("happy path", func(t *testing.T) {
-		client := NewFallbackClient(&http.Client{}, nil, "test", urls)
+		client := NewFallbackClient(&http.Client{}, nil, urls)
 		client.log = nopLogger
 		require.NotNil(t, client.httpDo)
 
@@ -65,7 +63,7 @@ func TestFallbackClient_Get(t *testing.T) {
 
 	t.Run("fallback on error", func(t *testing.T) {
 		var metrics mockClientMetrics
-		client := NewFallbackClient(nil, &metrics, "test", urls)
+		client := NewFallbackClient(nil, &metrics, urls)
 		client.log = nopLogger
 
 		var callCount int
@@ -91,7 +89,7 @@ func TestFallbackClient_Get(t *testing.T) {
 
 	t.Run("fallback on bad status code", func(t *testing.T) {
 		var metrics mockClientMetrics
-		client := NewFallbackClient(nil, &metrics, "test", urls)
+		client := NewFallbackClient(nil, &metrics, urls)
 		client.log = nopLogger
 
 		var callCount int
@@ -119,7 +117,7 @@ func TestFallbackClient_Get(t *testing.T) {
 	t.Run("all errors", func(t *testing.T) {
 		r := rand.New(rand.NewSource(time.Now().UnixNano()))
 		var metrics mockClientMetrics
-		client := NewFallbackClient(nil, &metrics, "test", urls)
+		client := NewFallbackClient(nil, &metrics, urls)
 		client.log = nopLogger
 
 		var callCount int
@@ -154,7 +152,7 @@ func TestFallbackClient_Get(t *testing.T) {
 			{nil, &http.Response{StatusCode: http.StatusNotFound}, "404"},
 		} {
 			var metrics mockClientMetrics
-			client := NewFallbackClient(nil, &metrics, "test", []url.URL{{Host: "error.example.com"}})
+			client := NewFallbackClient(nil, &metrics, []url.URL{{Host: "error.example.com"}})
 			client.log = nopLogger
 
 			client.httpDo = func(req *http.Request) (*http.Response, error) {
@@ -167,15 +165,14 @@ func TestFallbackClient_Get(t *testing.T) {
 			//nolint
 			_, _ = client.Get(ctx, "")
 
-			require.Equal(t, "test", metrics.GotRPCType, tt)
 			require.Equal(t, "error.example.com", metrics.GotHost.Hostname(), tt)
 			require.Equal(t, tt.WantMsg, metrics.GotErrMsg, tt)
 		}
 	})
 
 	t.Run("context canceled error", func(t *testing.T) {
 		var metrics mockClientMetrics
-		client := NewFallbackClient(nil, &metrics, "test", []url.URL{{Host: "error.example.com"}})
+		client := NewFallbackClient(nil, &metrics, []url.URL{{Host: "error.example.com"}})
 		client.log = nopLogger
 
 		client.httpDo = func(req *http.Request) (*http.Response, error) {

metrics/metrics.go

@@ -1,8 +1,11 @@
 package metrics
 
 const (
-	namespace          = "sl_exporter"
+	namespace = "sl_exporter"
+
+	// Subsystems
 	staticSubsystem    = "static"
 	cosmosSubsystem    = "cosmos"
 	cosmosValSubsystem = cosmosSubsystem + "_val"
+	refAPISubsystem    = "reference_api"
 )

metrics/reference_api.go

@@ -0,0 +1,35 @@
+package metrics
+
+import (
+	"net/url"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// ReferenceAPI records metrics for external http calls.
+type ReferenceAPI struct {
+	errorCounter *prometheus.CounterVec
+	// TODO(nix): Count requests and histogram of latency.
+}
+
+func NewHTTPRequest() *ReferenceAPI {
+	return &ReferenceAPI{
+		errorCounter: prometheus.NewCounterVec(
+			prometheus.CounterOpts{
+				Name: prometheus.BuildFQName(namespace, refAPISubsystem, "error_total"),
+				Help: "Number of errors encountered while making external calls to an API to gather reference data.",
+			},
+			[]string{"host", "reason"},
+		),
+	}
+}
+
+func (c ReferenceAPI) IncAPIError(host url.URL, reason string) {
+	c.errorCounter.WithLabelValues(host.Hostname(), reason).Inc()
+}
+
+func (c ReferenceAPI) Metrics() []prometheus.Collector {
+	return []prometheus.Collector{
+		c.errorCounter,
+	}
+}

metrics/reference_api_test.go

@@ -0,0 +1,29 @@
+package metrics
+
+import (
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReferenceAPI_IncAPIError(t *testing.T) {
+	t.Parallel()
+
+	reg := prometheus.NewRegistry()
+	metrics := NewHTTPRequest()
+	reg.MustRegister(metrics.Metrics()[0])
+
+	u, err := url.Parse("http://test.example/should/not/be/used")
+	require.NoError(t, err)
+
+	metrics.IncAPIError(*u, "timeout")
+
+	h := metricsHandler(reg)
+	r := httptest.NewRecorder()
+	h.ServeHTTP(r, stubRequest)
+
+	require.Contains(t, r.Body.String(), `sl_exporter_reference_api_error_total{host="test.example",reason="timeout"} 1`)
+}