feat(pencil): Add custom metrics using promhttp

.github/workflows/build_pr.yaml

@@ -6,12 +6,13 @@ on:
       - main
 jobs:
   build:
+    name: Build PR
     runs-on: ubuntu-latest
     steps:
-      - name: Set up Go ^1.18
+      - name: Set up Go ^1.21
         uses: actions/setup-go@v3
         with:
-          go-version: ^1.18
+          go-version: ^1.21
 
       - uses: actions/checkout@v3
 

.github/workflows/helm_release.yaml

@@ -14,10 +14,10 @@ jobs:
         with:
           string: ${{ github.repository }}
 
-      - name: Set up Go ^1.18
+      - name: Set up Go ^1.21
         uses: actions/setup-go@v3
         with:
-          go-version: ^1.18
+          go-version: ^1.21
 
       - name: Checkout
         uses: actions/checkout@v3

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.18 as build
+FROM golang:1.21 as build
 RUN go install golang.org/x/lint/golint@latest
 WORKDIR /build
 COPY . ./

charts/kubernetes-sidecar-injector/templates/mutatingwebhook.yaml

@@ -103,6 +103,7 @@ spec:
           imagePullPolicy: {{ .Values.image.pullPolicy }}
           args:
             - --port={{ .Values.container.port }}
+            - --metricsPort={{ .Values.container.metricsPort }}
             - --certFile=/opt/kubernetes-sidecar-injector/certs/cert.pem
             - --keyFile=/opt/kubernetes-sidecar-injector/certs/key.pem
             - --injectPrefix={{ trimSuffix "/" .Values.selectors.injectPrefix }}
@@ -116,6 +117,11 @@ spec:
             - name: https
               containerPort: {{ .Values.container.port }}
               protocol: TCP
+            {{- if ne .Values.container.port .Values.container.metricsPort }}
+            - name: metrics
+              containerPort: {{ .Values.container.metricsPort }}
+              protocol: TCP
+            {{- end }}
           livenessProbe:
             httpGet:
               path: /healthz

charts/kubernetes-sidecar-injector/templates/service.yaml

@@ -7,8 +7,13 @@ metadata:
     {{- include "common.labels" . | indent 4 }}
 spec:
   ports:
-  - name: https
-    port: {{ .Values.service.port }}
-    targetPort: https
+    - name: https
+      port: {{ .Values.service.port }}
+      targetPort: https
+  {{- if ne .Values.service.port .Values.service.metricsPort }}
+    - name: metrics
+      port: {{ .Values.service.metricsPort }}
+      targetPort: metrics
+  {{- end }}
   selector:
     {{- include "common.labels" . | indent 4 }}

charts/kubernetes-sidecar-injector/values.yaml

@@ -8,9 +8,11 @@ replicaCount: 1
 
 service:
   port: 443
+  metricsPort: 9090
 
 container:
   port: 8443
+  metricsPort: 9090
 
 podAnnotations: {}
 podLabels: {}

cmd/root.go

@@ -35,6 +35,7 @@ func Execute() {
 
 func init() {
 	rootCmd.Flags().IntVar(&httpdConf.Port, "port", 443, "server port.")
+	rootCmd.Flags().IntVar(&httpdConf.MetricsPort, "metricsPort", 9090, "metrics server port.")
 	rootCmd.Flags().StringVar(&httpdConf.CertFile, "certFile", "/etc/mutator/certs/cert.pem", "File containing tls certificate")
 	rootCmd.Flags().StringVar(&httpdConf.KeyFile, "keyFile", "/etc/mutator/certs/key.pem", "File containing tls private key")
 	rootCmd.Flags().BoolVar(&httpdConf.Local, "local", false, "Local run mode")

go.mod

@@ -1,11 +1,12 @@
 module github.com/expediagroup/kubernetes-sidecar-injector
 
 // Make sure you change the Dockerfile
-go 1.18
+go 1.21
 
 require (
 	github.com/ghodss/yaml v1.0.0
 	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.19.1
 	github.com/samber/lo v1.11.0
 	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/cobra v1.4.0
@@ -16,12 +17,14 @@ require (
 )
 
 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/evanphx/json-patch v4.12.0+incompatible // indirect
 	github.com/go-logr/logr v1.2.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/golang/protobuf v1.5.2 // indirect
-	github.com/google/go-cmp v0.5.5 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/google/gofuzz v1.1.0 // indirect
 	github.com/googleapis/gnostic v0.5.5 // indirect
 	github.com/imdario/mergo v0.3.5 // indirect
@@ -30,16 +33,19 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // 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
 	github.com/spf13/pflag v1.0.5 // indirect
 	golang.org/x/exp v0.0.0-20220303212507-bbda1eaf7a17 // indirect
-	golang.org/x/net v0.0.0-20211209124913-491a49abca63 // indirect
-	golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f // indirect
-	golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 // indirect
-	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b // indirect
-	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/net v0.20.0 // indirect
+	golang.org/x/oauth2 v0.16.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	golang.org/x/term v0.16.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
 	google.golang.org/appengine v1.6.7 // indirect
-	google.golang.org/protobuf v1.27.1 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect

go.sum

@@ -49,7 +49,11 @@ github.com/NYTimes/gziphandler v0.0.0-20170623195520-56545f4a5d46/go.mod h1:3wb0
 github.com/PuerkitoBio/purell v1.1.1/go.mod h1:c11w/QuzBsJSee3cPx9rAFu61PvFxuPbtSwDGJws/X0=
 github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578/go.mod h1:uGdkoq3SwY9Y+13GIhn11/XLaGBb4BfwItxLd5jeuXE=
 github.com/asaskevich/govalidator v0.0.0-20190424111038-f61b66f89f4a/go.mod h1:lB+ZfQJz7igIIfQNfa7Ml4HSf2uFQQRzpGGRXenZAgY=
+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/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+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/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
@@ -123,8 +127,9 @@ github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw
 github.com/golang/protobuf v1.4.3/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/golang/protobuf v1.5.1/go.mod h1:DopwsBzvsk0Fs44TXzsVbJyPhcCPeIwnvohx4u74HPM=
-github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.1/go.mod h1:xXMiIv4Fb/0kKde4SpL7qlzvu5cMJDRkFDxJfI9uaxA=
@@ -138,8 +143,9 @@ github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.3/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/gofuzz v1.1.0 h1:Hsa8mG0dQ46ij8Sl2AYJDUv1oA9/d6Vk+3LG99Oe02g=
 github.com/google/gofuzz v1.1.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
@@ -185,6 +191,7 @@ github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -201,7 +208,6 @@ github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9G
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/munnerz/goautoneg v0.0.0-20120707110453-a547fc61f48d/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f/go.mod h1:ZdcZmHo+o7JKHSa8/e818NopupXU1YMK5fe1lsApnBw=
-github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/nxadm/tail v1.4.4 h1:DQuhQpB1tVlglWS2hLQ5OV6B5r8aGxSrPc5Qo6uTN78=
 github.com/nxadm/tail v1.4.4/go.mod h1:kenIhsEOeOJmVchQTgglprH7qJGnHDVpk1VPCcaMI8A=
@@ -219,8 +225,17 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 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/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 v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+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 v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/samber/lo v1.11.0 h1:JfeYozXL1xfkhRUFOfH13ociyeiLSC/GRJjGKI668xM=
 github.com/samber/lo v1.11.0/go.mod h1:2I7tgIv8Q1SG2xEIkRq0F2i2zgxVpnyPOP0d3Gj2r+A=
@@ -333,8 +348,9 @@ golang.org/x/net v0.0.0-20210119194325-5f4716e94777/go.mod h1:m0MpNAwzfU5UDzcl9v
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210316092652-d523dce5a7f4/go.mod h1:RBQZq4jEuRlivfhVLdyRGr576XBO4/greRjx4P4O3yc=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-golang.org/x/net v0.0.0-20211209124913-491a49abca63 h1:iocB37TsdFuN6IBRZ+ry36wrkoV51/tl5vOWqkcPGvY=
 golang.org/x/net v0.0.0-20211209124913-491a49abca63/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
+golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -346,8 +362,9 @@ 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 v0.0.0-20210819190943-2bc19b11175f h1:Qmd2pbz05z7z6lm0DrgQVVPuBm92jqujBKMHMOlOQEw=
 golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
+golang.org/x/oauth2 v0.16.0 h1:aDkGMBSYxElaoP81NpoUoz2oo2R2wHdZpGToUxfyQrQ=
+golang.org/x/oauth2 v0.16.0/go.mod h1:hqZ+0LWXsiVoZpeld6jVt06P3adbS2Uu911W1SsJv2o=
 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=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -405,11 +422,12 @@ golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210831042530-f4d43177bf5e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 h1:id054HUawV2/6IGm2IV8KZQjqtwAOo2CYlOToYqa0d0=
-golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+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=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b h1:9zKuko04nR4gjZ4+DNjHqRlAJqbJETHwiNKDqTfOjfE=
 golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.16.0 h1:m+B6fahuftsE9qjo0VWp2FW0mB3MTJvR0BaMQrq0pmE=
+golang.org/x/term v0.16.0/go.mod h1:yn7UURbUtPyrVJPGPq404EukNFxcm/foM+bV/bfcDsY=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -418,8 +436,9 @@ golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.5/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -579,13 +598,14 @@ 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 v1.33.0 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 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
 gopkg.in/inf.v0 v0.9.1 h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=

pkg/httpd/simpleserver.go

@@ -9,6 +9,7 @@ import (
 	"github.com/expediagroup/kubernetes-sidecar-injector/pkg/admission"
 	"github.com/expediagroup/kubernetes-sidecar-injector/pkg/webhook"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	log "github.com/sirupsen/logrus"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
@@ -17,12 +18,13 @@ import (
 
 /*SimpleServer is the required config to create httpd server*/
 type SimpleServer struct {
-	Local    bool
-	Port     int
-	CertFile string
-	KeyFile  string
-	Patcher  webhook.SidecarInjectorPatcher
-	Debug    bool
+	Local       bool
+	Port        int
+	MetricsPort int
+	CertFile    string
+	KeyFile     string
+	Patcher     webhook.SidecarInjectorPatcher
+	Debug       bool
 }
 
 /*Start the simple http server supporting TLS*/
@@ -48,12 +50,34 @@ func (simpleServer *SimpleServer) Start() error {
 	mux.HandleFunc("/healthz", webhook.HealthCheckHandler)
 	mux.HandleFunc("/mutate", admissionHandler.HandleAdmission)
 
+	metricsHandler := promhttp.Handler()
+	if simpleServer.MetricsPort != simpleServer.Port {
+		go simpleServer.startMetricsServer(metricsHandler)
+	} else {
+		mux.Handle("/metrics", metricsHandler)
+	}
+
 	if simpleServer.Local {
 		return server.ListenAndServe()
 	}
 	return server.ListenAndServeTLS(simpleServer.CertFile, simpleServer.KeyFile)
 }
 
+func (simpleServer *SimpleServer) startMetricsServer(metricsHandler http.Handler) {
+	log.Printf("Starting metrics server on port %d\n", simpleServer.MetricsPort)
+	metricsRouter := http.NewServeMux()
+	metricsRouter.Handle("/metrics", metricsHandler)
+
+	metricsServer := &http.Server{
+		Addr:    fmt.Sprintf(":%d", simpleServer.MetricsPort),
+		Handler: metricsRouter,
+	}
+
+	if err := metricsServer.ListenAndServe(); err != nil {
+		log.Fatal("Failed to start metrics server:", err)
+	}
+}
+
 // CreateClient Create the server
 func (simpleServer *SimpleServer) CreateClient() (*kubernetes.Clientset, error) {
 	config, err := simpleServer.buildConfig()