Improve performances when Prometheus metrics are enabled

go.mod

@@ -49,7 +49,7 @@ require (
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/pires/go-proxyproto v0.6.1
 	github.com/pmezard/go-difflib v1.0.0
-	github.com/prometheus/client_golang v1.11.0
+	github.com/prometheus/client_golang v1.12.2-0.20220704083116-e8f91604d835
 	github.com/prometheus/client_model v0.2.0
 	github.com/rancher/go-rancher-metadata v0.0.0-20200311180630-7f4c936a06ac
 	github.com/sirupsen/logrus v1.8.1
@@ -155,7 +155,7 @@ require (
 	github.com/fsnotify/fsnotify v1.5.1 // indirect
 	github.com/fvbommel/sortorder v1.0.1 // indirect
 	github.com/go-errors/errors v1.0.1 // indirect
-	github.com/go-logfmt/logfmt v0.5.0 // indirect
+	github.com/go-logfmt/logfmt v0.5.1 // indirect
 	github.com/go-logr/logr v0.4.0 // indirect
 	github.com/go-resty/resty/v2 v2.1.1-0.20191201195748-d7b97669fe48 // indirect
 	github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 // indirect
@@ -266,8 +266,8 @@ require (
 	github.com/philhofer/fwd v1.1.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pquerna/otp v1.3.0 // indirect
-	github.com/prometheus/common v0.26.0 // indirect
+	github.com/prometheus/common v0.35.0 // indirect
-	github.com/prometheus/procfs v0.6.0 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
 	github.com/sacloud/libsacloud v1.36.2 // indirect
 	github.com/sanathkr/go-yaml v0.0.0-20170819195128-ed9d249f429b // indirect
 	github.com/santhosh-tekuri/jsonschema v1.2.4 // indirect
@@ -307,16 +307,16 @@ require (
 	go.uber.org/zap v1.18.1 // indirect
 	golang.org/x/crypto v0.0.0-20220427172511-eb4f295cb31f // indirect
 	golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 // indirect
-	golang.org/x/oauth2 v0.0.0-20210402161424-2e8d93401602 // indirect
+	golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b // indirect
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
-	golang.org/x/sys v0.0.0-20220307203707-22a9840ba4d7 // indirect
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
 	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 	google.golang.org/api v0.44.0 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/genproto v0.0.0-20210602131652-f16073e35f0c // indirect
-	google.golang.org/protobuf v1.27.1 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/ini.v1 v1.62.0 // indirect
 	gopkg.in/ns1/ns1-go.v2 v2.6.2 // indirect

go.sum

@@ -686,11 +686,13 @@ github.com/go-kit/kit v0.9.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2
 github.com/go-kit/kit v0.10.1-0.20200915143503-439c4d2ed3ea h1:CnEQOUv4ilElSwFB9g/lVmz206oLE4aNZDYngIY1Gvg=
 github.com/go-kit/kit v0.10.1-0.20200915143503-439c4d2ed3ea/go.mod h1:xUsJbQ/Fp4kEt7AFgCuvyX4a71u8h9jB8tj/ORgOZ7o=
 github.com/go-kit/log v0.1.0/go.mod h1:zbhenjAZHb184qTLMA9ZjW7ThYL0H2mk7Q6pNt4vbaY=
+github.com/go-kit/log v0.2.0/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
 github.com/go-ldap/ldap/v3 v3.1.3/go.mod h1:3rbOH3jRS2u6jg2rJnKAMLE/xQyCKIveG2Sa/Cohzb8=
 github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
 github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V4qmtdjCk=
-github.com/go-logfmt/logfmt v0.5.0 h1:TrB8swr/68K7m9CcGut2g3UOihhbcbiMAYiuTXdEih4=
 github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG1KdI/P7A=
+github.com/go-logfmt/logfmt v0.5.1 h1:otpy5pqBCBZ1ng9RQ0dPu4PN7ba75Y/aA+UpowDyNVA=
+github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/go-logr/logr v0.1.0/go.mod h1:ixOQHD9gLJUVQQ2ZOR7zLEifBX6tGkNJF4QyIY7sIas=
 github.com/go-logr/logr v0.2.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTgseGU=
 github.com/go-logr/logr v0.4.0 h1:K7/B1jt6fIBQVd4Owv2MqGQClcgf0R266+7C/QjRcLc=
@@ -1653,8 +1655,10 @@ github.com/prometheus/client_golang v1.1.0/go.mod h1:I1FGZT9+L76gKKOs5djB6ezCbFQ
 github.com/prometheus/client_golang v1.3.0/go.mod h1:hJaj2vgQTGQmVCsAACORcieXFeDPbaTKGT+JTgUa3og=
 github.com/prometheus/client_golang v1.4.0/go.mod h1:e9GMxYsXl05ICDXkRhurwBS4Q3OK1iX/F2sw+iXX5zU=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
-github.com/prometheus/client_golang v1.11.0 h1:HNkLOAEQMIDv/K+04rukrLx6ch7msSRwf3/SASFAGtQ=
 github.com/prometheus/client_golang v1.11.0/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
+github.com/prometheus/client_golang v1.12.1/go.mod h1:3Z9XVyYiZYEO+YQWt3RD2R3jrbd179Rt297l4aS6nDY=
+github.com/prometheus/client_golang v1.12.2-0.20220704083116-e8f91604d835 h1:sYuFGkrz0PtewSFk0Bg7p7jjiiklc6FUIWz+mFGQfD0=
+github.com/prometheus/client_golang v1.12.2-0.20220704083116-e8f91604d835/go.mod h1:RjnYTcBFM8s+WRft6oBqj4p5OgXJASPw5UFiI7w+GSs=
 github.com/prometheus/client_model v0.0.0-20171117100541-99fa1f4be8e5/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190115171406-56726106282f/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
@@ -1674,8 +1678,10 @@ github.com/prometheus/common v0.6.0/go.mod h1:eBmuwkDJBwy6iBfxCBob6t6dR6ENT/y+J+
 github.com/prometheus/common v0.7.0/go.mod h1:DjGbpBbp5NYNiECxcL/VnbXCCaQpKd3tt26CguLLsqA=
 github.com/prometheus/common v0.9.1/go.mod h1:yhUN8i9wzaXS3w1O07YhxHEBxD+W35wd8bs7vj7HSQ4=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
-github.com/prometheus/common v0.26.0 h1:iMAkS2TDoNWnKM+Kopnx/8tnEStIfpYA0ur0xQzzhMQ=
 github.com/prometheus/common v0.26.0/go.mod h1:M7rCNAaPfAosfx8veZJCuw84e35h3Cfd9VFqTh1DIvc=
+github.com/prometheus/common v0.32.1/go.mod h1:vu+V0TpY+O6vW9J44gczi3Ap/oXXR10b+M/gUGO4Hls=
+github.com/prometheus/common v0.35.0 h1:Eyr+Pw2VymWejHqCugNaQXkAi6KayVNxaHeu6khmFBE=
+github.com/prometheus/common v0.35.0/go.mod h1:phzohg0JFMnBEFGxTDbfu3QyL5GI8gTQJFhYO5B3mfA=
 github.com/prometheus/procfs v0.0.0-20180125133057-cb4147076ac7/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.0-20180725123919-05ee40e3a273/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
@@ -1690,8 +1696,9 @@ github.com/prometheus/procfs v0.0.5/go.mod h1:4A/X28fw3Fc593LaREMrKMqOKvUAntwMDa
 github.com/prometheus/procfs v0.0.8/go.mod h1:7Qr8sr6344vo1JqZ6HhLceV9o3AJ1Ff+GxbHq6oeK9A=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.2.0/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
-github.com/prometheus/procfs v0.6.0 h1:mxy4L2jP6qMonqmq+aTtOx1ifVWUgG/TAmntgbh3xv4=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
+github.com/prometheus/procfs v0.7.3 h1:4jVXhlkAyzOScmCkXBTOLRLTz8EeU+eyjrwB/EPq0VU=
+github.com/prometheus/procfs v0.7.3/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
 github.com/prometheus/tsdb v0.7.1/go.mod h1:qhTCs0VvXwvX/y3TZrWD7rabWM+ijKTux40TwIPHuXU=
 github.com/qri-io/jsonpointer v0.1.0/go.mod h1:DnJPaYgiKu56EuDp8TU5wFLdZIcAnb/uH9v37ZaMV64=
 github.com/qri-io/jsonschema v0.1.1/go.mod h1:QpzJ6gBQ0GYgGmh7mDQ1YsvvhSgE4rYj0k8t5MBOmUY=
@@ -2232,9 +2239,12 @@ golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1/go.mod h1:9tjilg8BloeKEkVJvy
 golang.org/x/net v0.0.0-20210428140749-89ef3d95e781/go.mod h1:OJAsFXCWl8Ukc7SiCT/9KSuxbyM7479/AVlXFRxuMCk=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210520170846-37e1c6afe023/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20211020060615-d418f374d309/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
+golang.org/x/net v0.0.0-20220225172249-27dd8689420f/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4 h1:HVyaeDAYux4pnY+D/SiwmLOR36ewZ4iGQIIrtnuCjFA=
 golang.org/x/net v0.0.0-20220425223048-2871e0cb64e4/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/oauth2 v0.0.0-20180724155351-3d292e4d0cdc/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -2251,8 +2261,10 @@ golang.org/x/oauth2 v0.0.0-20201208152858-08078c50e5b5/go.mod h1:KelEdhl1UZF7XfJ
 golang.org/x/oauth2 v0.0.0-20210218202405-ba52d332ba99/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
 golang.org/x/oauth2 v0.0.0-20210220000619-9bb904979d93/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
 golang.org/x/oauth2 v0.0.0-20210313182246-cd4f82c27b84/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
-golang.org/x/oauth2 v0.0.0-20210402161424-2e8d93401602 h1:0Ja1LBD+yisY6RWM/BH7TJVXWsSjs2VwBSmvSX4HdBc=
 golang.org/x/oauth2 v0.0.0-20210402161424-2e8d93401602/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
+golang.org/x/oauth2 v0.0.0-20210514164344-f6687ab2804c/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
+golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b h1:clP8eMhB30EHdc0bd2Twtq6kgU7yl5ub2cQLSdrv1Dg=
+golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b/go.mod h1:DAh4E804XQdzx2j+YRIaUnCqCV2RuMz24cGBJ5QYIrc=
 golang.org/x/perf v0.0.0-20180704124530-6e6d33e29852/go.mod h1:JLpeXjPJfIyPr5TlbXLkXWLhP8nz10XfvxElABhCtcw=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -2391,10 +2403,12 @@ golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211103235746-7861aae1554b/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220209214540-3681064d5158/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220307203707-22a9840ba4d7 h1:8IVLkfbr2cLhv0a/vKq4UFUcJym8RmDoDboxCFWEjYE=
 golang.org/x/sys v0.0.0-20220307203707-22a9840ba4d7/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a h1:dGzPydgVsqGcTRVwiLJ1jVbufYwmzD3LfVPLKsKg+0k=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210220032956-6a3ed077a48d/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
@@ -2658,8 +2672,9 @@ google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGj
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.28.0 h1:w43yiav+6bVFTBQFZX0r7ipe9JQ1QsbMgHwbBziscLw=
+google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/DataDog/dd-trace-go.v1 v1.38.1 h1:nAKgcpJLXRHF56cKCP3bN8gTTQmmNAZFEblbyGKhKTo=
 gopkg.in/DataDog/dd-trace-go.v1 v1.38.1/go.mod h1:GBhK4yaMJ1h329ivtKAqRNe1EZ944UnZwtz5lh7CnJc=
 gopkg.in/airbrake/gobrake.v2 v2.0.9/go.mod h1:/h5ZAUhDkGaJfjzjKLSjv6zCL6O0LLBxU4K+aSYdM/U=

pkg/metrics/prometheus.go

@@ -4,8 +4,6 @@ import (
 	"context"
 	"errors"
 	"net/http"
-	"sort"
-	"strings"
 	"sync"
 	"time"
 
@@ -15,7 +13,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/traefik/traefik/v2/pkg/config/dynamic"
 	"github.com/traefik/traefik/v2/pkg/log"
-	"github.com/traefik/traefik/v2/pkg/safe"
 	"github.com/traefik/traefik/v2/pkg/types"
 )
 
@@ -111,37 +108,33 @@ func initStandardRegistry(config *types.Prometheus) Registry {
 		buckets = config.Buckets
 	}
 
-	safe.Go(func() {
+	configReloads := newCounterFrom(stdprometheus.CounterOpts{
-		promState.ListenValueUpdates()
-	})
-
-	configReloads := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
 		Name: configReloadsTotalName,
 		Help: "Config reloads",
 	}, []string{})
-	configReloadsFailures := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+	configReloadsFailures := newCounterFrom(stdprometheus.CounterOpts{
 		Name: configReloadsFailuresTotalName,
 		Help: "Config failure reloads",
 	}, []string{})
-	lastConfigReloadSuccess := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+	lastConfigReloadSuccess := newGaugeFrom(stdprometheus.GaugeOpts{
 		Name: configLastReloadSuccessName,
 		Help: "Last config reload success",
 	}, []string{})
-	lastConfigReloadFailure := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+	lastConfigReloadFailure := newGaugeFrom(stdprometheus.GaugeOpts{
 		Name: configLastReloadFailureName,
 		Help: "Last config reload failure",
 	}, []string{})
-	tlsCertsNotAfterTimestamp := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+	tlsCertsNotAfterTimestamp := newGaugeFrom(stdprometheus.GaugeOpts{
 		Name: tlsCertsNotAfterTimestamp,
 		Help: "Certificate expiration timestamp",
 	}, []string{"cn", "serial", "sans"})
 
-	promState.describers = []func(chan<- *stdprometheus.Desc){
+	promState.vectors = []vector{
-		configReloads.cv.Describe,
+		configReloads.cv,
-		configReloadsFailures.cv.Describe,
+		configReloadsFailures.cv,
-		lastConfigReloadSuccess.gv.Describe,
+		lastConfigReloadSuccess.gv,
-		lastConfigReloadFailure.gv.Describe,
+		lastConfigReloadFailure.gv,
-		tlsCertsNotAfterTimestamp.gv.Describe,
+		tlsCertsNotAfterTimestamp.gv,
 	}
 
 	reg := &standardRegistry{
@@ -156,30 +149,30 @@ func initStandardRegistry(config *types.Prometheus) Registry {
 	}
 
 	if config.AddEntryPointsLabels {
-		entryPointReqs := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		entryPointReqs := newCounterFrom(stdprometheus.CounterOpts{
 			Name: entryPointReqsTotalName,
 			Help: "How many HTTP requests processed on an entrypoint, partitioned by status code, protocol, and method.",
 		}, []string{"code", "method", "protocol", "entrypoint"})
-		entryPointReqsTLS := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		entryPointReqsTLS := newCounterFrom(stdprometheus.CounterOpts{
 			Name: entryPointReqsTLSTotalName,
 			Help: "How many HTTP requests with TLS processed on an entrypoint, partitioned by TLS Version and TLS cipher Used.",
 		}, []string{"tls_version", "tls_cipher", "entrypoint"})
-		entryPointReqDurations := newHistogramFrom(promState.collectors, stdprometheus.HistogramOpts{
+		entryPointReqDurations := newHistogramFrom(stdprometheus.HistogramOpts{
 			Name:    entryPointReqDurationName,
 			Help:    "How long it took to process the request on an entrypoint, partitioned by status code, protocol, and method.",
 			Buckets: buckets,
 		}, []string{"code", "method", "protocol", "entrypoint"})
-		entryPointOpenConns := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+		entryPointOpenConns := newGaugeFrom(stdprometheus.GaugeOpts{
 			Name: entryPointOpenConnsName,
 			Help: "How many open connections exist on an entrypoint, partitioned by method and protocol.",
 		}, []string{"method", "protocol", "entrypoint"})
 
-		promState.describers = append(promState.describers, []func(chan<- *stdprometheus.Desc){
+		promState.vectors = append(promState.vectors,
-			entryPointReqs.cv.Describe,
+			entryPointReqs.cv,
-			entryPointReqsTLS.cv.Describe,
+			entryPointReqsTLS.cv,
-			entryPointReqDurations.hv.Describe,
+			entryPointReqDurations.hv,
-			entryPointOpenConns.gv.Describe,
+			entryPointOpenConns.gv,
-		}...)
+		)
 
 		reg.entryPointReqsCounter = entryPointReqs
 		reg.entryPointReqsTLSCounter = entryPointReqsTLS
@@ -188,30 +181,30 @@ func initStandardRegistry(config *types.Prometheus) Registry {
 	}
 
 	if config.AddRoutersLabels {
-		routerReqs := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		routerReqs := newCounterFrom(stdprometheus.CounterOpts{
 			Name: routerReqsTotalName,
 			Help: "How many HTTP requests are processed on a router, partitioned by service, status code, protocol, and method.",
 		}, []string{"code", "method", "protocol", "router", "service"})
-		routerReqsTLS := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		routerReqsTLS := newCounterFrom(stdprometheus.CounterOpts{
 			Name: routerReqsTLSTotalName,
 			Help: "How many HTTP requests with TLS are processed on a router, partitioned by service, TLS Version, and TLS cipher Used.",
 		}, []string{"tls_version", "tls_cipher", "router", "service"})
-		routerReqDurations := newHistogramFrom(promState.collectors, stdprometheus.HistogramOpts{
+		routerReqDurations := newHistogramFrom(stdprometheus.HistogramOpts{
 			Name:    routerReqDurationName,
 			Help:    "How long it took to process the request on a router, partitioned by service, status code, protocol, and method.",
 			Buckets: buckets,
 		}, []string{"code", "method", "protocol", "router", "service"})
-		routerOpenConns := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+		routerOpenConns := newGaugeFrom(stdprometheus.GaugeOpts{
 			Name: routerOpenConnsName,
 			Help: "How many open connections exist on a router, partitioned by service, method, and protocol.",
 		}, []string{"method", "protocol", "router", "service"})
 
-		promState.describers = append(promState.describers, []func(chan<- *stdprometheus.Desc){
+		promState.vectors = append(promState.vectors,
-			routerReqs.cv.Describe,
+			routerReqs.cv,
-			routerReqsTLS.cv.Describe,
+			routerReqsTLS.cv,
-			routerReqDurations.hv.Describe,
+			routerReqDurations.hv,
-			routerOpenConns.gv.Describe,
+			routerOpenConns.gv,
-		}...)
+		)
 		reg.routerReqsCounter = routerReqs
 		reg.routerReqsTLSCounter = routerReqsTLS
 		reg.routerReqDurationHistogram, _ = NewHistogramWithScale(routerReqDurations, time.Second)
@@ -219,40 +212,40 @@ func initStandardRegistry(config *types.Prometheus) Registry {
 	}
 
 	if config.AddServicesLabels {
-		serviceReqs := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		serviceReqs := newCounterFrom(stdprometheus.CounterOpts{
 			Name: serviceReqsTotalName,
 			Help: "How many HTTP requests processed on a service, partitioned by status code, protocol, and method.",
 		}, []string{"code", "method", "protocol", "service"})
-		serviceReqsTLS := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		serviceReqsTLS := newCounterFrom(stdprometheus.CounterOpts{
 			Name: serviceReqsTLSTotalName,
 			Help: "How many HTTP requests with TLS processed on a service, partitioned by TLS version and TLS cipher.",
 		}, []string{"tls_version", "tls_cipher", "service"})
-		serviceReqDurations := newHistogramFrom(promState.collectors, stdprometheus.HistogramOpts{
+		serviceReqDurations := newHistogramFrom(stdprometheus.HistogramOpts{
 			Name:    serviceReqDurationName,
 			Help:    "How long it took to process the request on a service, partitioned by status code, protocol, and method.",
 			Buckets: buckets,
 		}, []string{"code", "method", "protocol", "service"})
-		serviceOpenConns := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+		serviceOpenConns := newGaugeFrom(stdprometheus.GaugeOpts{
 			Name: serviceOpenConnsName,
 			Help: "How many open connections exist on a service, partitioned by method and protocol.",
 		}, []string{"method", "protocol", "service"})
-		serviceRetries := newCounterFrom(promState.collectors, stdprometheus.CounterOpts{
+		serviceRetries := newCounterFrom(stdprometheus.CounterOpts{
 			Name: serviceRetriesTotalName,
 			Help: "How many request retries happened on a service.",
 		}, []string{"service"})
-		serviceServerUp := newGaugeFrom(promState.collectors, stdprometheus.GaugeOpts{
+		serviceServerUp := newGaugeFrom(stdprometheus.GaugeOpts{
 			Name: serviceServerUpName,
 			Help: "service server is up, described by gauge value of 0 or 1.",
 		}, []string{"service", "url"})
 
-		promState.describers = append(promState.describers, []func(chan<- *stdprometheus.Desc){
+		promState.vectors = append(promState.vectors,
-			serviceReqs.cv.Describe,
+			serviceReqs.cv,
-			serviceReqsTLS.cv.Describe,
+			serviceReqsTLS.cv,
-			serviceReqDurations.hv.Describe,
+			serviceReqDurations.hv,
-			serviceOpenConns.gv.Describe,
+			serviceOpenConns.gv,
-			serviceRetries.cv.Describe,
+			serviceRetries.cv,
-			serviceServerUp.gv.Describe,
+			serviceServerUp.gv,
-		}...)
+		)
 
 		reg.serviceReqsCounter = serviceReqs
 		reg.serviceReqsTLSCounter = serviceReqsTLS
@@ -287,64 +280,93 @@ func registerPromState(ctx context.Context) bool {
 // It then converts the configuration to the optimized package internal format
 // and sets it to the promState.
 func OnConfigurationUpdate(conf dynamic.Configuration, entryPoints []string) {
-	dynamicConfig := newDynamicConfig()
+	dynCfg := newDynamicConfig()
 
 	for _, value := range entryPoints {
-		dynamicConfig.entryPoints[value] = true
+		dynCfg.entryPoints[value] = true
+	}
+
+	if conf.HTTP == nil {
+		promState.SetDynamicConfig(dynCfg)
+		return
 	}
 
 	for name := range conf.HTTP.Routers {
-		dynamicConfig.routers[name] = true
+		dynCfg.routers[name] = true
 	}
 
 	for serviceName, service := range conf.HTTP.Services {
-		dynamicConfig.services[serviceName] = make(map[string]bool)
+		dynCfg.services[serviceName] = make(map[string]bool)
 		if service.LoadBalancer != nil {
 			for _, server := range service.LoadBalancer.Servers {
-				dynamicConfig.services[serviceName][server.URL] = true
+				dynCfg.services[serviceName][server.URL] = true
 			}
 		}
 	}
 
-	promState.SetDynamicConfig(dynamicConfig)
+	promState.SetDynamicConfig(dynCfg)
 }
 
 func newPrometheusState() *prometheusState {
 	return &prometheusState{
-		collectors:    make(chan *collector),
 		dynamicConfig: newDynamicConfig(),
-		state:         make(map[string]*collector),
+		deletedURLs:   make(map[string]string),
 	}
 }
 
-type prometheusState struct {
+type vector interface {
-	collectors chan *collector
+	stdprometheus.Collector
-	describers []func(ch chan<- *stdprometheus.Desc)
+	DeletePartialMatch(labels stdprometheus.Labels) int
+}
 
-	mtx           sync.Mutex
+type prometheusState struct {
-	dynamicConfig *dynamicConfig
+	vectors []vector
-	state         map[string]*collector
+
+	mtx             sync.Mutex
+	dynamicConfig   *dynamicConfig
+	deletedEP       []string
+	deletedRouters  []string
+	deletedServices []string
+	deletedURLs     map[string]string
 }
 
 func (ps *prometheusState) SetDynamicConfig(dynamicConfig *dynamicConfig) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
-	ps.dynamicConfig = dynamicConfig
-}
 
-func (ps *prometheusState) ListenValueUpdates() {
+	for ep := range ps.dynamicConfig.entryPoints {
-	for collector := range ps.collectors {
+		if _, ok := dynamicConfig.entryPoints[ep]; !ok {
-		ps.mtx.Lock()
+			ps.deletedEP = append(ps.deletedEP, ep)
-		ps.state[collector.id] = collector
+		}
-		ps.mtx.Unlock()
 	}
+
+	for router := range ps.dynamicConfig.routers {
+		if _, ok := dynamicConfig.routers[router]; !ok {
+			ps.deletedRouters = append(ps.deletedRouters, router)
+		}
+	}
+
+	for service, serV := range ps.dynamicConfig.services {
+		actualService, ok := dynamicConfig.services[service]
+		if !ok {
+			ps.deletedServices = append(ps.deletedServices, service)
+			continue
+		}
+		for url := range serV {
+			if _, ok := actualService[url]; !ok {
+				ps.deletedURLs[service] = url
+			}
+		}
+	}
+
+	ps.dynamicConfig = dynamicConfig
 }
 
 // Describe implements prometheus.Collector and simply calls
 // the registered describer functions.
 func (ps *prometheusState) Describe(ch chan<- *stdprometheus.Desc) {
-	for _, desc := range ps.describers {
+	for _, v := range ps.vectors {
-		desc(ch)
+		v.Describe(ch)
 	}
 }
 
@@ -354,49 +376,52 @@ func (ps *prometheusState) Describe(ch chan<- *stdprometheus.Desc) {
 // The removal happens only after their Collect method was called to ensure that
 // also those metrics will be exported on the current scrape.
 func (ps *prometheusState) Collect(ch chan<- stdprometheus.Metric) {
+	for _, v := range ps.vectors {
+		v.Collect(ch)
+	}
+
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
 
-	var outdatedKeys []string
+	for _, ep := range ps.deletedEP {
-	for key, cs := range ps.state {
+		if !ps.dynamicConfig.hasEntryPoint(ep) {
-		cs.collector.Collect(ch)
+			ps.DeletePartialMatch(map[string]string{"entrypoint": ep})
-
-		if ps.isOutdated(cs) {
-			outdatedKeys = append(outdatedKeys, key)
 		}
 	}
 
-	for _, key := range outdatedKeys {
+	for _, router := range ps.deletedRouters {
-		ps.state[key].delete()
+		if !ps.dynamicConfig.hasRouter(router) {
-		delete(ps.state, key)
+			ps.DeletePartialMatch(map[string]string{"router": router})
+		}
 	}
+
+	for _, service := range ps.deletedServices {
+		if !ps.dynamicConfig.hasService(service) {
+			ps.DeletePartialMatch(map[string]string{"service": service})
+		}
+	}
+
+	for service, url := range ps.deletedURLs {
+		if !ps.dynamicConfig.hasServerURL(service, url) {
+			ps.DeletePartialMatch(map[string]string{"service": service, "url": url})
+		}
+	}
+
+	ps.deletedEP = nil
+	ps.deletedRouters = nil
+	ps.deletedServices = nil
+	ps.deletedURLs = make(map[string]string)
 }
 
-// isOutdated checks whether the passed collector has labels that mark
+// DeletePartialMatch deletes all metrics where the variable labels contain all of those passed in as labels.
-// it as belonging to an outdated configuration of Traefik.
+// The order of the labels does not matter.
-func (ps *prometheusState) isOutdated(collector *collector) bool {
+// It returns the number of metrics deleted.
-	labels := collector.labels
+func (ps *prometheusState) DeletePartialMatch(labels stdprometheus.Labels) int {
-
+	var count int
-	if entrypointName, ok := labels["entrypoint"]; ok && !ps.dynamicConfig.hasEntryPoint(entrypointName) {
+	for _, elem := range ps.vectors {
-		return true
+		count += elem.DeletePartialMatch(labels)
 	}
-
+	return count
-	if routerName, ok := labels["router"]; ok {
-		if !ps.dynamicConfig.hasRouter(routerName) {
-			return true
-		}
-	}
-
-	if serviceName, ok := labels["service"]; ok {
-		if !ps.dynamicConfig.hasService(serviceName) {
-			return true
-		}
-		if url, ok := labels["url"]; ok && !ps.dynamicConfig.hasServerURL(serviceName, url) {
-			return true
-		}
-	}
-
-	return false
 }
 
 func newDynamicConfig() *dynamicConfig {
@@ -440,42 +465,15 @@ func (d *dynamicConfig) hasServerURL(serviceName, serverURL string) bool {
 	return false
 }
 
-func newCollector(metricName string, labels stdprometheus.Labels, c stdprometheus.Collector, deleteFn func()) *collector {
+func newCounterFrom(opts stdprometheus.CounterOpts, labelNames []string) *counter {
-	return &collector{
-		id:        buildMetricID(metricName, labels),
-		labels:    labels,
-		collector: c,
-		delete:    deleteFn,
-	}
-}
-
-// collector wraps a Collector object from the Prometheus client library.
-// It adds information on how many generations this metric should be present
-// in the /metrics output, relative to the time it was last tracked.
-type collector struct {
-	id        string
-	labels    stdprometheus.Labels
-	collector stdprometheus.Collector
-	delete    func()
-}
-
-func buildMetricID(metricName string, labels stdprometheus.Labels) string {
-	var labelNamesValues []string
-	for name, value := range labels {
-		labelNamesValues = append(labelNamesValues, name, value)
-	}
-	sort.Strings(labelNamesValues)
-	return metricName + ":" + strings.Join(labelNamesValues, "|")
-}
-
-func newCounterFrom(collectors chan<- *collector, opts stdprometheus.CounterOpts, labelNames []string) *counter {
 	cv := stdprometheus.NewCounterVec(opts, labelNames)
 	c := &counter{
-		name:       opts.Name,
+		name:             opts.Name,
-		cv:         cv,
+		cv:               cv,
-		collectors: collectors,
+		labelNamesValues: make([]string, 0, 16),
 	}
 	if len(labelNames) == 0 {
+		c.collector = cv.WithLabelValues()
 		c.Add(0)
 	}
 	return c
@@ -485,39 +483,37 @@ type counter struct {
 	name             string
 	cv               *stdprometheus.CounterVec
 	labelNamesValues labelNamesValues
-	collectors       chan<- *collector
+	collector        stdprometheus.Counter
 }
 
 func (c *counter) With(labelValues ...string) metrics.Counter {
+	lnv := c.labelNamesValues.With(labelValues...)
 	return &counter{
 		name:             c.name,
 		cv:               c.cv,
-		labelNamesValues: c.labelNamesValues.With(labelValues...),
+		labelNamesValues: lnv,
-		collectors:       c.collectors,
+		collector:        c.cv.With(lnv.ToLabels()),
 	}
 }
 
 func (c *counter) Add(delta float64) {
-	labels := c.labelNamesValues.ToLabels()
+	c.collector.Add(delta)
-	collector := c.cv.With(labels)
-	collector.Add(delta)
-	c.collectors <- newCollector(c.name, labels, collector, func() {
-		c.cv.Delete(labels)
-	})
 }
 
 func (c *counter) Describe(ch chan<- *stdprometheus.Desc) {
 	c.cv.Describe(ch)
 }
 
-func newGaugeFrom(collectors chan<- *collector, opts stdprometheus.GaugeOpts, labelNames []string) *gauge {
+func newGaugeFrom(opts stdprometheus.GaugeOpts, labelNames []string) *gauge {
 	gv := stdprometheus.NewGaugeVec(opts, labelNames)
 	g := &gauge{
-		name:       opts.Name,
+		name:             opts.Name,
-		gv:         gv,
+		gv:               gv,
-		collectors: collectors,
+		labelNamesValues: make([]string, 0, 16),
 	}
+
 	if len(labelNames) == 0 {
+		g.collector = gv.WithLabelValues()
 		g.Set(0)
 	}
 	return g
@@ -527,46 +523,37 @@ type gauge struct {
 	name             string
 	gv               *stdprometheus.GaugeVec
 	labelNamesValues labelNamesValues
-	collectors       chan<- *collector
+	collector        stdprometheus.Gauge
 }
 
 func (g *gauge) With(labelValues ...string) metrics.Gauge {
+	lnv := g.labelNamesValues.With(labelValues...)
 	return &gauge{
 		name:             g.name,
 		gv:               g.gv,
-		labelNamesValues: g.labelNamesValues.With(labelValues...),
+		labelNamesValues: lnv,
-		collectors:       g.collectors,
+		collector:        g.gv.With(lnv.ToLabels()),
 	}
 }
 
 func (g *gauge) Add(delta float64) {
-	labels := g.labelNamesValues.ToLabels()
+	g.collector.Add(delta)
-	collector := g.gv.With(labels)
-	collector.Add(delta)
-	g.collectors <- newCollector(g.name, labels, collector, func() {
-		g.gv.Delete(labels)
-	})
 }
 
 func (g *gauge) Set(value float64) {
-	labels := g.labelNamesValues.ToLabels()
+	g.collector.Set(value)
-	collector := g.gv.With(labels)
-	collector.Set(value)
-	g.collectors <- newCollector(g.name, labels, collector, func() {
-		g.gv.Delete(labels)
-	})
 }
 
 func (g *gauge) Describe(ch chan<- *stdprometheus.Desc) {
 	g.gv.Describe(ch)
 }
 
-func newHistogramFrom(collectors chan<- *collector, opts stdprometheus.HistogramOpts, labelNames []string) *histogram {
+func newHistogramFrom(opts stdprometheus.HistogramOpts, labelNames []string) *histogram {
 	hv := stdprometheus.NewHistogramVec(opts, labelNames)
 	return &histogram{
-		name:       opts.Name,
+		name:             opts.Name,
-		hv:         hv,
+		hv:               hv,
-		collectors: collectors,
+		labelNamesValues: make([]string, 0, 16),
 	}
 }
 
@@ -574,28 +561,21 @@ type histogram struct {
 	name             string
 	hv               *stdprometheus.HistogramVec
 	labelNamesValues labelNamesValues
-	collectors       chan<- *collector
+	collector        stdprometheus.Observer
 }
 
 func (h *histogram) With(labelValues ...string) metrics.Histogram {
+	lnv := h.labelNamesValues.With(labelValues...)
 	return &histogram{
 		name:             h.name,
 		hv:               h.hv,
-		labelNamesValues: h.labelNamesValues.With(labelValues...),
+		labelNamesValues: lnv,
-		collectors:       h.collectors,
+		collector:        h.hv.With(lnv.ToLabels()),
 	}
 }
 
 func (h *histogram) Observe(value float64) {
-	labels := h.labelNamesValues.ToLabels()
+	h.collector.Observe(value)
-	observer := h.hv.With(labels)
-	observer.Observe(value)
-	// Do a type assertion to be sure that prometheus will be able to call the Collect method.
-	if collector, ok := observer.(stdprometheus.Histogram); ok {
-		h.collectors <- newCollector(h.name, labels, collector, func() {
-			h.hv.Delete(labels)
-		})
-	}
 }
 
 func (h *histogram) Describe(ch chan<- *stdprometheus.Desc) {
@@ -618,7 +598,7 @@ func (lvs labelNamesValues) With(labelValues ...string) labelNamesValues {
 // ToLabels is a convenience method to convert a labelNamesValues
 // to the native prometheus.Labels.
 func (lvs labelNamesValues) ToLabels() stdprometheus.Labels {
-	labels := stdprometheus.Labels{}
+	labels := make(map[string]string, len(lvs)/2)
 	for i := 0; i < len(lvs); i += 2 {
 		labels[lvs[i]] = lvs[i+1]
 	}

pkg/metrics/prometheus_test.go

@@ -17,8 +17,7 @@ import (
 )
 
 func TestRegisterPromState(t *testing.T) {
-	// Reset state of global promState.
+	t.Cleanup(promState.reset)
-	defer promState.reset()
 
 	testCases := []struct {
 		desc                 string
@@ -88,21 +87,10 @@ func TestRegisterPromState(t *testing.T) {
 	}
 }
 
-// reset is a utility method for unit testing. It should be called after each
-// test run that changes promState internally in order to avoid dependencies
-// between unit tests.
-func (ps *prometheusState) reset() {
-	ps.collectors = make(chan *collector)
-	ps.describers = []func(ch chan<- *prometheus.Desc){}
-	ps.dynamicConfig = newDynamicConfig()
-	ps.state = make(map[string]*collector)
-}
-
 func TestPrometheus(t *testing.T) {
 	promState = newPrometheusState()
 	promRegistry = prometheus.NewRegistry()
-	// Reset state of global promState.
+	t.Cleanup(promState.reset)
-	defer promState.reset()
 
 	prometheusRegistry := RegisterPrometheus(context.Background(), &types.Prometheus{AddEntryPointsLabels: true, AddRoutersLabels: true, AddServicesLabels: true})
 	defer promRegistry.Unregister(promState)
@@ -361,30 +349,40 @@ func TestPrometheus(t *testing.T) {
 func TestPrometheusMetricRemoval(t *testing.T) {
 	promState = newPrometheusState()
 	promRegistry = prometheus.NewRegistry()
-	// Reset state of global promState.
+	t.Cleanup(promState.reset)
-	defer promState.reset()
 
 	prometheusRegistry := RegisterPrometheus(context.Background(), &types.Prometheus{AddEntryPointsLabels: true, AddServicesLabels: true, AddRoutersLabels: true})
 	defer promRegistry.Unregister(promState)
 
-	conf := dynamic.Configuration{
+	conf1 := dynamic.Configuration{
 		HTTP: th.BuildConfiguration(
 			th.WithRouters(
-				th.WithRouter("foo@providerName",
+				th.WithRouter("foo@providerName", th.WithServiceName("bar")),
-					th.WithServiceName("bar")),
+				th.WithRouter("router2", th.WithServiceName("bar@providerName")),
 			),
-			th.WithLoadBalancerServices(th.WithService("bar@providerName",
+			th.WithLoadBalancerServices(
-				th.WithServers(th.WithServer("http://localhost:9000"))),
+				th.WithService("bar@providerName", th.WithServers(
+					th.WithServer("http://localhost:9000"),
+					th.WithServer("http://localhost:9999"),
+				)),
+				th.WithService("service1", th.WithServers(th.WithServer("http://localhost:9000"))),
 			),
-			func(cfg *dynamic.HTTPConfiguration) {
-				cfg.Services["fii"] = &dynamic.Service{
-					Weighted: &dynamic.WeightedRoundRobin{},
-				}
-			},
 		),
 	}
 
-	OnConfigurationUpdate(conf, []string{"entrypoint1"})
+	conf2 := dynamic.Configuration{
+		HTTP: th.BuildConfiguration(
+			th.WithRouters(
+				th.WithRouter("foo@providerName", th.WithServiceName("bar")),
+			),
+			th.WithLoadBalancerServices(
+				th.WithService("bar@providerName", th.WithServers(th.WithServer("http://localhost:9000"))),
+			),
+		),
+	}
+
+	OnConfigurationUpdate(conf1, []string{"entrypoint1", "entrypoint2"})
+	OnConfigurationUpdate(conf2, []string{"entrypoint1"})
 
 	// Register some metrics manually that are not part of the active configuration.
 	// Those metrics should be part of the /metrics output on the first scrape but
@@ -393,22 +391,21 @@ func TestPrometheusMetricRemoval(t *testing.T) {
 		EntryPointReqsCounter().
 		With("entrypoint", "entrypoint2", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
 		Add(1)
+	prometheusRegistry.
+		RouterReqsCounter().
+		With("router", "router2", "service", "bar@providerName", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
+		Add(1)
 	prometheusRegistry.
 		ServiceReqsCounter().
-		With("service", "service2", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
+		With("service", "service1", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
 		Add(1)
 	prometheusRegistry.
 		ServiceServerUpGauge().
-		With("service", "service1", "url", "http://localhost:9999").
+		With("service", "bar@providerName", "url", "http://localhost:9999").
 		Set(1)
-	prometheusRegistry.
-		RouterReqsCounter().
-		With("router", "router2", "service", "service2", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
-		Add(1)
 
-	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName, serviceReqsTotalName, serviceServerUpName)
+	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName, routerReqsTotalName, serviceReqsTotalName, serviceServerUpName)
-	assertMetricsAbsent(t, mustScrape(), entryPointReqsTotalName, serviceReqsTotalName, serviceServerUpName)
+	assertMetricsAbsent(t, mustScrape(), entryPointReqsTotalName, routerReqsTotalName, serviceReqsTotalName, serviceServerUpName)
-	assertMetricsAbsent(t, mustScrape(), routerReqsTotalName, routerReqDurationName, routerOpenConnsName)
 
 	// To verify that metrics belonging to active configurations are not removed
 	// here the counter examples.
@@ -418,24 +415,39 @@ func TestPrometheusMetricRemoval(t *testing.T) {
 		Add(1)
 	prometheusRegistry.
 		RouterReqsCounter().
-		With("router", "foo@providerName", "service", "bar@providerName", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
+		With("router", "foo@providerName", "service", "bar", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
 		Add(1)
+	prometheusRegistry.
+		ServiceReqsCounter().
+		With("service", "bar@providerName", "code", strconv.Itoa(http.StatusOK), "method", http.MethodGet, "protocol", "http").
+		Add(1)
+	prometheusRegistry.
+		ServiceServerUpGauge().
+		With("service", "bar@providerName", "url", "http://localhost:9000").
+		Set(1)
 
 	delayForTrackingCompletion()
 
-	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName)
+	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName, serviceReqsTotalName, serviceServerUpName, routerReqsTotalName)
-	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName)
+	assertMetricsExist(t, mustScrape(), entryPointReqsTotalName, serviceReqsTotalName, serviceServerUpName, routerReqsTotalName)
-	assertMetricsExist(t, mustScrape(), routerReqsTotalName)
-	assertMetricsExist(t, mustScrape(), routerReqsTotalName)
 }
 
 func TestPrometheusRemovedMetricsReset(t *testing.T) {
-	// Reset state of global promState.
+	t.Cleanup(promState.reset)
-	defer promState.reset()
 
 	prometheusRegistry := RegisterPrometheus(context.Background(), &types.Prometheus{AddEntryPointsLabels: true, AddServicesLabels: true})
 	defer promRegistry.Unregister(promState)
 
+	conf1 := dynamic.Configuration{
+		HTTP: th.BuildConfiguration(
+			th.WithLoadBalancerServices(th.WithService("service",
+				th.WithServers(th.WithServer("http://localhost:9000"))),
+			),
+		),
+	}
+	OnConfigurationUpdate(conf1, []string{"entrypoint1", "entrypoint2"})
+	OnConfigurationUpdate(dynamic.Configuration{}, nil)
+
 	labelNamesValues := []string{
 		"service", "service",
 		"code", strconv.Itoa(http.StatusOK),
@@ -467,12 +479,24 @@ func TestPrometheusRemovedMetricsReset(t *testing.T) {
 	assertCounterValue(t, 1, findMetricFamily(serviceReqsTotalName, metricsFamilies), labelNamesValues...)
 }
 
+// reset is a utility method for unit testing.
+// It should be called after each test run that changes promState internally
+// in order to avoid dependencies between unit tests.
+func (ps *prometheusState) reset() {
+	ps.dynamicConfig = newDynamicConfig()
+	ps.vectors = nil
+	ps.deletedEP = nil
+	ps.deletedRouters = nil
+	ps.deletedServices = nil
+	ps.deletedURLs = make(map[string]string)
+}
+
 // Tracking and gathering the metrics happens concurrently.
-// In practice this is no problem, because in case a tracked metric would miss
+// In practice this is no problem, because in case a tracked metric would miss the current scrape,
-// the current scrape, it would just be there in the next one.
+// it would just be there in the next one.
-// That we can test reliably the tracking of all metrics here, we sleep
+// That we can test reliably the tracking of all metrics here,
-// for a short amount of time, to make sure the metric will be present
+// we sleep for a short amount of time,
-// in the next scrape.
+// to make sure the metric will be present in the next scrape.
 func delayForTrackingCompletion() {
 	time.Sleep(250 * time.Millisecond)
 }

pkg/middlewares/metrics/metrics.go

@@ -103,8 +103,9 @@ func (m *metricsMiddleware) ServeHTTP(rw http.ResponseWriter, req *http.Request)
 	labels = append(labels, m.baseLabels...)
 	labels = append(labels, "method", getMethod(req), "protocol", getRequestProtocol(req))
 
-	m.openConnsGauge.With(labels...).Add(1)
+	openConnsGauge := m.openConnsGauge.With(labels...)
-	defer m.openConnsGauge.With(labels...).Add(-1)
+	openConnsGauge.Add(1)
+	defer openConnsGauge.Add(-1)
 
 	// TLS metrics
 	if req.TLS != nil {
@@ -122,8 +123,7 @@ func (m *metricsMiddleware) ServeHTTP(rw http.ResponseWriter, req *http.Request)
 
 	labels = append(labels, "code", strconv.Itoa(recorder.getCode()))
 
-	histograms := m.reqDurationHistogram.With(labels...)
+	m.reqDurationHistogram.With(labels...).ObserveFromStart(start)
-	histograms.ObserveFromStart(start)
 
 	m.reqsCounter.With(labels...).Add(1)
 }