fix: Concurrency issues with Global Registry, issues with incorrect P…

…ath in Metrics (#197)

* Fixes related to concurrency with global registry, fixes for metrics path, support for cache metrics

* Remove go1.20 support, add note in README.

* Compare against correct path, only get method if request is for middleware

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
   Build:
     strategy:
       matrix:
-        go-version: [1.20.x, 1.21.x, 1.22.x]
+        go-version: [1.21.x, 1.22.x]
         platform: [ubuntu-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
@@ -20,5 +20,5 @@ jobs:
         with:
           go-version: '${{ matrix.go-version }}'
       - name: Run Test
-        run: go test -race
+        run: go test -race -count=1
 

README.md

@@ -2,6 +2,8 @@
 
 Prometheus middleware for gofiber.
 
+**Note: Requires Go 1.21 and above**
+
 ![Release](https://img.shields.io/github/release/ansrivas/fiberprometheus.svg)
 [![Discord](https://img.shields.io/badge/discord-join%20channel-7289DA)](https://gofiber.io/discord)
 ![Test](https://github.com/ansrivas/fiberprometheus/workflows/Test/badge.svg)
@@ -14,6 +16,7 @@ Following metrics are available by default:
 http_requests_total
 http_request_duration_seconds
 http_requests_in_progress_total
+http_cache_results
 ```
 
 ### Install v2
@@ -39,7 +42,6 @@ func main() {
   // This here will appear as a label, one can also use
   // fiberprometheus.NewWith(servicename, namespace, subsystem )
   // or
-  // NOTE: Following is not available in v1
   // labels := map[string]string{"custom_label1":"custom_value1", "custom_label2":"custom_value2"}
   // fiberprometheus.NewWithLabels(labels, namespace, subsystem )
   prometheus := fiberprometheus.New("my-service-name")
@@ -58,42 +60,11 @@ func main() {
 }
 ```
 
-### Example using V1
-
-```go
-package main
-
-import (
-  "github.com/gofiber/fiber"
-  "github.com/ansrivas/fiberprometheus"
-)
-
-func main() {
-  app := fiber.New()
-
-  // This here will appear as a label, one can also use
-  // fiberprometheus.NewWith(servicename, namespace, subsystem )
-  prometheus := fiberprometheus.New("my-service-name")
-  prometheus.RegisterAt(app, "/metrics")
-  app.Use(prometheus.Middleware)
-
-  app.Get("/", func(c *fiber.Ctx) {
-    c.Send("Hello World")
-  })
-
-  app.Post("/some", func(c *fiber.Ctx) {
-    c.Send("Welcome!")
-  })
-
-  app.Listen(3000)
-}
-```
-
 ### Result
 
 - Hit the default url at http://localhost:3000
 - Navigate to http://localhost:3000/metrics
 
 ### Grafana Board
 
-- https://grafana.com/grafana/dashboards/14331
+- https://grafana.com/grafana/dashboards/14331

go.mod

@@ -1,29 +1,30 @@
 module github.com/ansrivas/fiberprometheus/v2
 
-go 1.20
+go 1.21
 
 require (
-	github.com/gofiber/adaptor/v2 v2.2.1
 	github.com/gofiber/fiber/v2 v2.52.2
 	github.com/prometheus/client_golang v1.19.0
+	github.com/valyala/fasthttp v1.52.0
 )
 
 require (
-	github.com/andybalholm/brotli v1.0.5 // indirect
+	github.com/andybalholm/brotli v1.1.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
-	github.com/google/uuid v1.5.0 // indirect
-	github.com/klauspost/compress v1.17.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/klauspost/compress v1.17.7 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-runewidth v0.0.15 // 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
-	github.com/rivo/uniseg v0.4.4 // indirect
+	github.com/philhofer/fwd v1.1.2 // indirect
+	github.com/prometheus/client_model v0.6.0 // indirect
+	github.com/prometheus/common v0.50.0 // indirect
+	github.com/prometheus/procfs v0.13.0 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/tinylib/msgp v1.1.8 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/valyala/fasthttp v1.51.0 // indirect
 	github.com/valyala/tcplisten v1.0.0 // indirect
-	golang.org/x/sys v0.16.0 // indirect
-	google.golang.org/protobuf v1.32.0 // indirect
+	golang.org/x/sys v0.18.0 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 )

go.sum

@@ -1,46 +1,80 @@
-github.com/andybalholm/brotli v1.0.5 h1:8uQZIdzKmjc/iuPu7O2ioW48L81FgatrcpfFmiq/cCs=
-github.com/andybalholm/brotli v1.0.5/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
+github.com/andybalholm/brotli v1.1.0 h1:eLKJA0d02Lf0mVpIDgYnqXcUn0GqVmEFny3VuID1U3M=
+github.com/andybalholm/brotli v1.1.0/go.mod h1:sms7XGricyQI9K10gOSf56VKKWS4oLer58Q+mhRPtnY=
 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/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/gofiber/adaptor/v2 v2.2.1 h1:givE7iViQWlsTR4Jh7tB4iXzrlKBgiraB/yTdHs9Lv4=
-github.com/gofiber/adaptor/v2 v2.2.1/go.mod h1:AhR16dEqs25W2FY/l8gSj1b51Azg5dtPDmm+pruNOrc=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gofiber/fiber/v2 v2.52.2 h1:b0rYH6b06Df+4NyrbdptQL8ifuxw/Tf2DgfkZkDaxEo=
 github.com/gofiber/fiber/v2 v2.52.2/go.mod h1:KEOE+cXMhXG0zHc9d8+E38hoX+ZN7bhOtgeF2oT6jrQ=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
-github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
-github.com/google/uuid v1.5.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/klauspost/compress v1.17.0 h1:Rnbp4K9EjcDuVuHtd0dgA4qNuv9yKDYKK1ulpJwgrqM=
-github.com/klauspost/compress v1.17.0/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/klauspost/compress v1.17.7 h1:ehO88t2UGzQK66LMdE8tibEd1ErmzZjNEqWkjLAKQQg=
+github.com/klauspost/compress v1.17.7/go.mod h1:Di0epgTjJY877eYKx5yC51cX2A2Vl2ibi7bDH9ttBbw=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZgg3U=
 github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/philhofer/fwd v1.1.2 h1:bnDivRJ1EWPjUIRXV5KfORO897HTbpFAQddBdE8t7Gw=
+github.com/philhofer/fwd v1.1.2/go.mod h1:qkPdfjR2SIEbspLqpe1tO4n5yICnr2DY7mqEx2tUTP0=
 github.com/prometheus/client_golang v1.19.0 h1:ygXvpU1AoN1MhdzckN+PyD9QJOSD4x7kmXYlnfbA6JU=
 github.com/prometheus/client_golang v1.19.0/go.mod h1:ZRM9uEAypZakd+q/x7+gmsvXdURP+DABIEIjnmDdp+k=
-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/prometheus/client_model v0.6.0 h1:k1v3CzpSRUTrKMppY35TLwPvxHqBu0bYgxZzqGIgaos=
+github.com/prometheus/client_model v0.6.0/go.mod h1:NTQHnmxFpouOD0DpvP4XujX3CdOAGQPoaGhyTchlyt8=
+github.com/prometheus/common v0.50.0 h1:YSZE6aa9+luNa2da6/Tik0q0A5AbR+U003TItK57CPQ=
+github.com/prometheus/common v0.50.0/go.mod h1:wHFBCEVWVmHMUpg7pYcOm2QUR/ocQdYSJVQJKnHc3xQ=
+github.com/prometheus/procfs v0.13.0 h1:GqzLlQyfsPbaEHaQkO7tbDlriv/4o5Hudv6OXHGKX7o=
+github.com/prometheus/procfs v0.13.0/go.mod h1:cd4PFCR54QLnGKPaKGA6l+cfuNXtht43ZKY6tow0Y1g=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
-github.com/rivo/uniseg v0.4.4 h1:8TfxU8dW6PdqD27gjM8MVNuicgxIjxpm4K7x4jp8sis=
-github.com/rivo/uniseg v0.4.4/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
+github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+github.com/tinylib/msgp v1.1.8 h1:FCXC1xanKO4I8plpHGH2P7koL/RzZs12l/+r7vakfm0=
+github.com/tinylib/msgp v1.1.8/go.mod h1:qkpG+2ldGg4xRFmx+jfTvZPxfGFhi64BcnL9vkCm/Tw=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
-github.com/valyala/fasthttp v1.51.0 h1:8b30A5JlZ6C7AS81RsWjYMQmrZG6feChmgAolCl1SqA=
-github.com/valyala/fasthttp v1.51.0/go.mod h1:oI2XroL+lI7vdXyYoQk03bXBThfFl2cVdIA3Xl7cH8g=
+github.com/valyala/fasthttp v1.52.0 h1:wqBQpxH71XW0e2g+Og4dzQM8pk34aFYlA1Ga8db7gU0=
+github.com/valyala/fasthttp v1.52.0/go.mod h1:hf5C4QnVMkNXMspnsUlfM3WitlgYflyhHYoKol/szxQ=
 github.com/valyala/tcplisten v1.0.0 h1:rBHj/Xf+E1tRGZyWIWwJDiRY0zc1Js+CV5DqwacVSA8=
 github.com/valyala/tcplisten v1.0.0/go.mod h1:T0xQ8SeCZGxckz9qRXTfG43PvQ/mcWh7FwZEA7Ioqkc=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.3.0/go.mod h1:MBQ8lrhLObU/6UmLb4fmbmk5OcyYmqtbGd/9yIeKjEE=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.16.0 h1:xWw16ngr6ZMtmxDyKyIgsE93KNKz5HKmMa3b8ALHidU=
-golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-google.golang.org/protobuf v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
-google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
+golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.3.0/go.mod h1:q750SLmJuPmVoN1blW3UFBPREJfb1KmY3vwxfr+nFDA=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.5.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.4.0/go.mod h1:UE5sM2OK9E/d67R0ANs2xJizIymRP5gJU295PvKXxjQ=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
+google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

middleware.go

@@ -25,8 +25,9 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/gofiber/adaptor/v2"
 	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/fiber/v2/middleware/adaptor"
+	"github.com/gofiber/fiber/v2/utils"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -38,10 +39,16 @@ type FiberPrometheus struct {
 	requestsTotal   *prometheus.CounterVec
 	requestDuration *prometheus.HistogramVec
 	requestInFlight *prometheus.GaugeVec
+	cacheHeaderKey  string
+	cacheCounter    *prometheus.CounterVec
 	defaultURL      string
 }
 
 func create(registry prometheus.Registerer, serviceName, namespace, subsystem string, labels map[string]string) *FiberPrometheus {
+	if registry == nil {
+		registry = prometheus.NewRegistry()
+	}
+
 	constLabels := make(prometheus.Labels)
 	if serviceName != "" {
 		constLabels["service"] = serviceName
@@ -58,6 +65,16 @@ func create(registry prometheus.Registerer, serviceName, namespace, subsystem st
 		},
 		[]string{"status_code", "method", "path"},
 	)
+
+	cacheCounter := promauto.With(registry).NewCounterVec(
+		prometheus.CounterOpts{
+			Name:        prometheus.BuildFQName(namespace, subsystem, "cache_results"),
+			Help:        "Counts all cache hits by status code, method, and path",
+			ConstLabels: constLabels,
+		},
+		[]string{"status_code", "method", "path", "cache_result"},
+	)
+
 	histogram := promauto.With(registry).NewHistogramVec(prometheus.HistogramOpts{
 		Name:        prometheus.BuildFQName(namespace, subsystem, "request_duration_seconds"),
 		Help:        "Duration of all HTTP requests by status code, method and path.",
@@ -120,14 +137,22 @@ func create(registry prometheus.Registerer, serviceName, namespace, subsystem st
 		requestsTotal:   counter,
 		requestDuration: histogram,
 		requestInFlight: gauge,
+		cacheHeaderKey:  "X-Cache",
+		cacheCounter:    cacheCounter,
 		defaultURL:      "/metrics",
 	}
 }
 
+// CustomCacheKey allows to set a custom header key for caching
+// By default it is set to "X-Cache", the fiber default
+func (ps *FiberPrometheus) CustomCacheKey(cacheHeaderKey string) {
+	ps.cacheHeaderKey = cacheHeaderKey
+}
+
 // New creates a new instance of FiberPrometheus middleware
 // serviceName is available as a const label
 func New(serviceName string) *FiberPrometheus {
-	return create(prometheus.DefaultRegisterer, serviceName, "http", "", nil)
+	return create(nil, serviceName, "http", "", nil)
 }
 
 // NewWith creates a new instance of FiberPrometheus middleware but with an ability
@@ -138,7 +163,7 @@ func New(serviceName string) *FiberPrometheus {
 // For e.g. namespace = "my_app", subsystem = "http" then metrics would be
 // `my_app_http_requests_total{...,service= "serviceName"}`
 func NewWith(serviceName, namespace, subsystem string) *FiberPrometheus {
-	return create(prometheus.DefaultRegisterer, serviceName, namespace, subsystem, nil)
+	return create(nil, serviceName, namespace, subsystem, nil)
 }
 
 // NewWithLabels creates a new instance of FiberPrometheus middleware but with an ability
@@ -150,7 +175,7 @@ func NewWith(serviceName, namespace, subsystem string) *FiberPrometheus {
 // then then metrics would become
 // `my_app_http_requests_total{...,key1= "value1", key2= "value2" }`
 func NewWithLabels(labels map[string]string, namespace, subsystem string) *FiberPrometheus {
-	return create(prometheus.DefaultRegisterer, "", namespace, subsystem, labels)
+	return create(nil, "", namespace, subsystem, labels)
 }
 
 // NewWithRegistry creates a new instance of FiberPrometheus middleware but with an ability
@@ -176,12 +201,13 @@ func (ps *FiberPrometheus) RegisterAt(app fiber.Router, url string, handlers ...
 // Middleware is the actual default middleware implementation
 func (ps *FiberPrometheus) Middleware(ctx *fiber.Ctx) error {
 	start := time.Now()
-	method := ctx.Route().Method
+	path := string(ctx.Request().RequestURI())
 
-	if ctx.Route().Path == ps.defaultURL {
+	if path == ps.defaultURL {
 		return ctx.Next()
 	}
 
+	method := ctx.Route().Method
 	ps.requestInFlight.WithLabelValues(method).Inc()
 	defer func() {
 		ps.requestInFlight.WithLabelValues(method).Dec()
@@ -200,11 +226,19 @@ func (ps *FiberPrometheus) Middleware(ctx *fiber.Ctx) error {
 		status = ctx.Response().StatusCode()
 	}
 
-	path := ctx.Route().Path
-
+	// Get status as string
 	statusCode := strconv.Itoa(status)
+
+	// Update total requests counter
 	ps.requestsTotal.WithLabelValues(statusCode, method, path).Inc()
 
+	// Update the cache counter
+	cacheResult := utils.CopyString(ctx.GetRespHeader(ps.cacheHeaderKey, ""))
+	if cacheResult != "" {
+		ps.cacheCounter.WithLabelValues(statusCode, method, path, cacheResult).Inc()
+	}
+
+	// Update the request duration histogram
 	elapsed := float64(time.Since(start).Nanoseconds()) / 1e9
 	ps.requestDuration.WithLabelValues(statusCode, method, path).Observe(elapsed)