[DEVOPS-694] Move metrics to root

metrics/dummy.go

@@ -0,0 +1,10 @@
+package metrics
+
+// Dummy is a handy instnce of a dummy instrumenter, most of the times it will be used on tests.
+var Dummy = &dummy{}
+
+// dummy is a dummy implementation of Instrumenter.
+type dummy struct{}
+
+func (d *dummy) SetClusterOK(namespace string, name string)    {}
+func (d *dummy) SetClusterError(namespace string, name string) {}

metrics/metrics.go

@@ -0,0 +1,78 @@
+package metrics
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	promNamespace           = "redis_operator"
+	promControllerSubsystem = "controller"
+)
+
+// Instrumenter is the interface that will collect the metrics and has ability to send/expose those metrics.
+type Instrumenter interface {
+	SetClusterOK(namespace string, name string)
+	SetClusterError(namespace string, name string)
+}
+
+// PromMetrics implements the instrumenter so the metrics can be managed by Prometheus.
+type PromMetrics struct {
+	// Metrics fields.
+	clusterOK *prometheus.GaugeVec // clusterOk is the status of a cluster
+
+	// Instrumentation fields.
+	registry prometheus.Registerer
+	path     string
+	mux      *http.ServeMux
+}
+
+// NewPrometheusMetrics returns a new PromMetrics object.
+func NewPrometheusMetrics(path string, mux *http.ServeMux) *PromMetrics {
+	// Create metrics.
+	clusterOK := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: promNamespace,
+		Subsystem: promControllerSubsystem,
+		Name:      "cluster_ok",
+		Help:      "Number of failover clusters managed by the operator.",
+	}, []string{"namespace", "name"})
+
+	// Create Prometheus registry, use this instead of the prometheus default registry.
+	// TODO: Do we need go default instrumentation bout the go process metrics?
+	promReg := prometheus.NewRegistry()
+
+	// Create the instance.
+	p := &PromMetrics{
+		clusterOK: clusterOK,
+
+		registry: promReg,
+		path:     path,
+		mux:      mux,
+	}
+
+	// Register metrics on prometheus.
+	p.register()
+
+	// Register prometheus handler so we can serve the metrics.
+	handler := promhttp.HandlerFor(promReg, promhttp.HandlerOpts{})
+	mux.Handle(path, handler)
+
+	return p
+}
+
+// register will register all the required prometheus metrics on the Prometheus collector.
+func (p *PromMetrics) register() {
+	p.registry.MustRegister(p.clusterOK)
+}
+
+// SetClusterOK set the cluster status to OK
+func (p *PromMetrics) SetClusterOK(namespace string, name string) {
+	p.clusterOK.WithLabelValues(namespace, name).Set(1)
+}
+
+// SetClusterError set the cluster status to Error
+func (p *PromMetrics) SetClusterError(namespace string, name string) {
+	p.clusterOK.WithLabelValues(namespace, name).Set(0)
+}

metrics/metrics_test.go

@@ -0,0 +1,118 @@
+package metrics_test
+
+import (
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/spotahome/redis-operator/metrics"
+)
+
+func TestPrometheusMetrics(t *testing.T) {
+
+	tests := []struct {
+		name       string
+		addMetrics func(pm *metrics.PromMetrics)
+		expMetrics []string
+		expCode    int
+	}{
+		{
+			name: "Setting OK should give an OK",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterOK("testns", "test")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns"} 1`,
+			},
+			expCode: http.StatusOK,
+		},
+		{
+			name: "Setting Error should give an Error",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterError("testns", "test")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns"} 0`,
+			},
+			expCode: http.StatusOK,
+		},
+		{
+			name: "Setting Error after ok should give an Error",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterOK("testns", "test")
+				pm.SetClusterError("testns", "test")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns"} 0`,
+			},
+			expCode: http.StatusOK,
+		},
+		{
+			name: "Setting OK after Error should give an OK",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterError("testns", "test")
+				pm.SetClusterOK("testns", "test")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns"} 1`,
+			},
+			expCode: http.StatusOK,
+		},
+		{
+			name: "Multiple clusters should appear",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterOK("testns", "test")
+				pm.SetClusterOK("testns", "test2")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns"} 1`,
+				`redis_operator_controller_cluster_ok{name="test2",namespace="testns"} 1`,
+			},
+			expCode: http.StatusOK,
+		},
+		{
+			name: "Same name on different namespaces should appear",
+			addMetrics: func(pm *metrics.PromMetrics) {
+				pm.SetClusterOK("testns1", "test")
+				pm.SetClusterOK("testns2", "test")
+			},
+			expMetrics: []string{
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns1"} 1`,
+				`redis_operator_controller_cluster_ok{name="test",namespace="testns2"} 1`,
+			},
+			expCode: http.StatusOK,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			assert := assert.New(t)
+
+			path := "/awesome-metrics"
+
+			// Create the muxer for testing.
+			mx := http.NewServeMux()
+			pm := metrics.NewPrometheusMetrics(path, mx)
+
+			// Add metrics to prometheus.
+			test.addMetrics(pm)
+
+			// Make the request to the metrics.
+			req := httptest.NewRequest("GET", path, nil)
+			w := httptest.NewRecorder()
+			mx.ServeHTTP(w, req)
+
+			resp := w.Result()
+			if assert.Equal(test.expCode, resp.StatusCode) {
+				body, _ := ioutil.ReadAll(resp.Body)
+				// Check all the metrics are present.
+				for _, expMetric := range test.expMetrics {
+					assert.Contains(string(body), expMetric)
+				}
+			}
+		})
+	}
+}