add validation test for v3 metrics for all its endpoints (#20094)

add unit test for v3 metrics for all its exposed endpoints

Bonus:
  - support OpenMetrics encoding
  - adds boot time for prometheus
  - continueOnError is better to serve as
    much metrics as possible.

cmd/server_test.go

@@ -35,6 +35,7 @@ import (
 	"time"
 
 	"github.com/dustin/go-humanize"
+	jwtgo "github.com/golang-jwt/jwt/v4"
 	"github.com/minio/minio-go/v7/pkg/set"
 	xhttp "github.com/minio/minio/internal/http"
 	"github.com/minio/pkg/v3/policy"
@@ -122,6 +123,9 @@ func runAllTests(suite *TestSuiteCommon, c *check) {
 	suite.TestObjectMultipartListError(c)
 	suite.TestObjectValidMD5(c)
 	suite.TestObjectMultipart(c)
+	suite.TestMetricsV3Handler(c)
+	suite.TestBucketSQSNotificationWebHook(c)
+	suite.TestBucketSQSNotificationAMQP(c)
 	suite.TearDownSuite(c)
 }
 
@@ -189,6 +193,36 @@ func (s *TestSuiteCommon) TearDownSuite(c *check) {
 	s.testServer.Stop()
 }
 
+const (
+	defaultPrometheusJWTExpiry = 100 * 365 * 24 * time.Hour
+)
+
+func (s *TestSuiteCommon) TestMetricsV3Handler(c *check) {
+	jwt := jwtgo.NewWithClaims(jwtgo.SigningMethodHS512, jwtgo.StandardClaims{
+		ExpiresAt: time.Now().UTC().Add(defaultPrometheusJWTExpiry).Unix(),
+		Subject:   s.accessKey,
+		Issuer:    "prometheus",
+	})
+
+	token, err := jwt.SignedString([]byte(s.secretKey))
+	c.Assert(err, nil)
+
+	for _, cpath := range globalMetricsV3CollectorPaths {
+		request, err := newTestSignedRequest(http.MethodGet, s.endPoint+minioReservedBucketPath+metricsV3Path+string(cpath),
+			0, nil, s.accessKey, s.secretKey, s.signer)
+		c.Assert(err, nil)
+
+		request.Header.Set("Authorization", "Bearer "+token)
+
+		// execute the request.
+		response, err := s.client.Do(request)
+		c.Assert(err, nil)
+
+		// assert the http response status code.
+		c.Assert(response.StatusCode, http.StatusOK)
+	}
+}
+
 func (s *TestSuiteCommon) TestBucketSQSNotificationWebHook(c *check) {
 	// Sample bucket notification.
 	bucketNotificationBuf := `<NotificationConfiguration><QueueConfiguration><Event>s3:ObjectCreated:Put</Event><Filter><S3Key><FilterRule><Name>prefix</Name><Value>images/</Value></FilterRule></S3Key></Filter><Id>1</Id><Queue>arn:minio:sqs:us-east-1:444455556666:webhook</Queue></QueueConfiguration></NotificationConfiguration>`