feat: support prometheus metrics (#76)

**Background**
To enhance monitoring and observability, we have introduced Prometheus
metrics support in the project. These metrics will help us better
understand the system's performance and identify potential bottlenecks.

**New Features**
In this PR, we have added the following eight Prometheus metrics:

1. `opengemini_client_query_total` Count all queries
2. `opengemini_client_query_database_total` Count of opengemini queries
and classify using database
3. `opengemini_client_query_latency` Calculate the average of the
queries
4. `opengemini_client_query_database_latency` Calculate the average of
the queries and classify using database
5. `opengemini_client_write_total` Count of opengemini writes
6. `opengemini_client_write_database_total` Count of opengemini writes
and classify using database
7. `opengemini_client_write_latency` Calculate the average of the writes
8. `opengemini_client_write_database_latency` Calculate the average of
the writes and classify using database

**Impact**
This change does not affect existing functionality; it solely adds
monitoring metrics.
Ensure that the Prometheus server configuration in the deployment
environment is set up to scrape these new metrics.
Prometheus dependency was introduced for this project, and the project
dependency is no longer pure.

Signed-off-by: Young Xu <[email protected]>

go.mod

@@ -2,10 +2,21 @@ module github.com/openGemini/opengemini-client-go
 
 go 1.19
 
-require github.com/stretchr/testify v1.8.4
+require (
+	github.com/prometheus/client_golang v1.19.1
+	github.com/stretchr/testify v1.9.0
+)
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/kr/text v0.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.5.0 // indirect
+	github.com/prometheus/common v0.48.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,10 +1,32 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
-github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+github.com/prometheus/client_golang v1.19.1 h1:wZWJDwK+NameRJuPGDhlnFgx8e8HN3XHQeLaYJFJBOE=
+github.com/prometheus/client_golang v1.19.1/go.mod h1:mP78NwGzrVks5S2H6ab8+ZZGJLZUq1hoULYBAYBw1Ho=
+github.com/prometheus/client_model v0.5.0 h1:VQw1hfvPvk3Uv6Qf29VrPF32JB6rtbgI6cYPYQjL0Qw=
+github.com/prometheus/client_model v0.5.0/go.mod h1:dTiFglRmd66nLR9Pv9f0mZi7B7fk5Pm3gvsjB5tr+kI=
+github.com/prometheus/common v0.48.0 h1:QO8U2CdOzSn1BBsmXJXduaaW+dY/5QLjfB8svtSzKKE=
+github.com/prometheus/common v0.48.0/go.mod h1:0/KsvlIEfPQCQ5I2iNSAWKPZziNCvRs5EC6ILDTlAPc=
+github.com/prometheus/procfs v0.12.0 h1:jluTpSng7V9hY0O2R9DzzJHYb2xULk9VTR1V1R/k6Bo=
+github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
+google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

opengemini/client_impl.go

@@ -22,6 +22,7 @@ type client struct {
 	cli       *http.Client
 	prevIdx   atomic.Int32
 	dataChan  sync.Map
+	metrics   *metrics
 
 	cancel context.CancelFunc
 }
@@ -62,6 +63,7 @@ func newClient(c *Config) (Client, error) {
 		config:    c,
 		endpoints: buildEndpoints(c.Addresses, c.TlsEnabled),
 		cli:       newHttpClient(*c),
+		metrics:   newMetricsProvider(),
 		cancel:    cancel,
 	}
 	client.prevIdx.Store(-1)

opengemini/metrics.go

@@ -0,0 +1,118 @@
+package opengemini
+
+import "github.com/prometheus/client_golang/prometheus"
+
+const (
+	MetricsNamespace = "opengemini"
+	MetricsSubsystem = "client"
+)
+
+var _ prometheus.Collector = (*metrics)(nil)
+
+// metrics custom indicators, implementing the prometheus.Collector interface
+type metrics struct {
+	// queryCounter count all queries
+	queryCounter prometheus.Counter
+	// writeCounter count all write requests
+	writeCounter prometheus.Counter
+	// queryLatency calculate the average of the queries, unit milliseconds
+	queryLatency prometheus.Summary
+	// writeLatency calculate the average of the writes, unit milliseconds
+	writeLatency prometheus.Summary
+	// queryDatabaseCounter Count queries and classify using measurement
+	queryDatabaseCounter *prometheus.CounterVec
+	// writeDatabaseCounter count write requests and classify using measurement
+	writeDatabaseCounter *prometheus.CounterVec
+	// queryDatabaseLatency calculate the average of the queries for database, unit milliseconds
+	queryDatabaseLatency *prometheus.SummaryVec
+	// writeDatabaseLatency calculate the average of the writes for database, unit milliseconds
+	writeDatabaseLatency *prometheus.SummaryVec
+}
+
+func (m *metrics) Describe(chan<- *prometheus.Desc) {}
+
+func (m *metrics) Collect(ch chan<- prometheus.Metric) {
+	ch <- m.queryCounter
+	ch <- m.writeCounter
+	ch <- m.queryLatency
+	ch <- m.writeLatency
+	m.queryDatabaseCounter.Collect(ch)
+	m.writeDatabaseCounter.Collect(ch)
+	m.queryDatabaseLatency.Collect(ch)
+	m.writeDatabaseLatency.Collect(ch)
+}
+
+// newMetricsProvider returns metrics registered to registerer.
+func newMetricsProvider() *metrics {
+	constLabels := map[string]string{
+		"client": "go", // distinguish from other language client
+	}
+	constQuantiles := map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001}
+	labelNames := []string{"database"}
+
+	m := &metrics{
+		queryCounter: prometheus.NewCounter(prometheus.CounterOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "query_total",
+			Help:        "Count of opengemini queries",
+			ConstLabels: constLabels,
+		}),
+		writeCounter: prometheus.NewCounter(prometheus.CounterOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "write_total",
+			Help:        "Count of opengemini writes",
+			ConstLabels: constLabels,
+		}),
+		queryLatency: prometheus.NewSummary(prometheus.SummaryOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "query_latency",
+			Help:        "Calculate the average of the queries",
+			ConstLabels: constLabels,
+			Objectives:  constQuantiles,
+		}),
+		writeLatency: prometheus.NewSummary(prometheus.SummaryOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "write_latency",
+			Help:        "Calculate the average of the writes",
+			ConstLabels: constLabels,
+			Objectives:  constQuantiles,
+		}),
+		queryDatabaseCounter: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "query_database_total",
+			Help:        "Count of opengemini queries and classify using measurement",
+			ConstLabels: constLabels,
+		}, labelNames),
+		writeDatabaseCounter: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "write_database_total",
+			Help:        "Count of opengemini writes and classify using measurement",
+			ConstLabels: constLabels,
+		}, labelNames),
+		queryDatabaseLatency: prometheus.NewSummaryVec(prometheus.SummaryOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "query_database_latency",
+			Help:        "Calculate the average of the queries for database",
+			ConstLabels: constLabels,
+			Objectives:  constQuantiles,
+		}, labelNames),
+		writeDatabaseLatency: prometheus.NewSummaryVec(prometheus.SummaryOpts{
+			Namespace:   MetricsNamespace,
+			Subsystem:   MetricsSubsystem,
+			Name:        "write_database_latency",
+			Help:        "Calculate the average of the writes for database",
+			ConstLabels: constLabels,
+			Objectives:  constQuantiles,
+		}, labelNames),
+	}
+
+	prometheus.MustRegister(m)
+	return m
+}

opengemini/query.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"time"
 )
 
 type Query struct {
@@ -30,7 +31,17 @@ func (c *client) Query(q Query) (*QueryResult, error) {
 	req.queryValues.Add("rp", q.RetentionPolicy)
 	req.queryValues.Add("epoch", q.Precision.Epoch())
 
+	// metric
+	c.metrics.queryCounter.Add(1)
+	c.metrics.queryDatabaseCounter.WithLabelValues(q.Database).Add(1)
+	startAt := time.Now()
+
 	resp, err := c.executeHttpGet(UrlQuery, req)
+
+	cost := float64(time.Since(startAt).Milliseconds())
+	c.metrics.queryLatency.Observe(cost)
+	c.metrics.queryDatabaseLatency.WithLabelValues(q.Database).Observe(cost)
+
 	if err != nil {
 		return nil, errors.New("query request failed, error: " + err.Error())
 	}

opengemini/write.go

@@ -154,5 +154,16 @@ func (c *client) innerWrite(database string, buffer *bytes.Buffer) (*http.Respon
 		req.header.Set("Accept-Encoding", "gzip")
 	}
 	req.queryValues.Add("db", database)
-	return c.executeHttpPost(UrlWrite, req)
+
+	c.metrics.writeCounter.Add(1)
+	c.metrics.writeDatabaseCounter.WithLabelValues(database).Add(1)
+	startAt := time.Now()
+
+	response, err := c.executeHttpPost(UrlWrite, req)
+
+	cost := float64(time.Since(startAt).Milliseconds())
+	c.metrics.writeLatency.Observe(cost)
+	c.metrics.writeDatabaseLatency.WithLabelValues(database).Observe(cost)
+
+	return response, err
 }