go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/Masterminds/semver/v3 v3.2.0 // indirect
 	github.com/Microsoft/go-winio v0.6.0 // indirect
 	github.com/Nvveen/Gotty v0.0.0-20120604004816-cd527374f1e5 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.1.3 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/containerd/continuity v0.3.0 // indirect
@@ -30,18 +31,24 @@ require (
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
 	github.com/huandu/xstrings v1.3.3 // indirect
 	github.com/imdario/mergo v0.3.12 // indirect
-	github.com/kr/pretty v0.3.0 // indirect
+	github.com/kr/pretty v0.3.1 // indirect
 	github.com/mattn/go-runewidth v0.0.13 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/mitchellh/copystructure v1.0.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.0 // indirect
 	github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.0.2 // indirect
 	github.com/opencontainers/runc v1.1.5 // indirect
+	github.com/prometheus/client_golang v1.16.0 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.42.0 // indirect
+	github.com/prometheus/procfs v0.10.1 // indirect
 	github.com/qri-io/jsonpointer v0.1.1 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
 	github.com/rogpeppe/go-internal v1.10.0 // indirect
@@ -52,6 +59,7 @@ require (
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	github.com/xeipuuv/gojsonschema v1.2.0 // indirect
 	google.golang.org/genproto v0.0.0-20220314164441-57ef72a4c106 // indirect
+	google.golang.org/protobuf v1.30.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
@@ -88,7 +96,7 @@ require (
 	go.opencensus.io v0.24.0 // indirect
 	golang.org/x/crypto v0.8.0 // indirect
 	golang.org/x/mod v0.9.0 // indirect
-	golang.org/x/sys v0.7.0 // indirect
+	golang.org/x/sys v0.8.0 // indirect
 	golang.org/x/term v0.7.0 // indirect
 	golang.org/x/tools v0.7.0 // indirect
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect

go.sum

@@ -80,6 +80,8 @@ github.com/alecthomas/kong v0.2.1-0.20190708041108-0548c6b1afae/go.mod h1:+inYUS
 github.com/alecthomas/kong-hcl v0.1.8-0.20190615233001-b21fea9723c8/go.mod h1:MRgZdU3vrFd05IQ89AxUZ0aYdF39BYoNFa324SodPCA=
 github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
+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/bsm/ginkgo/v2 v2.7.0 h1:ItPMPH90RbmZJt5GtkcNvIRuGEdwlBItdNVoyzaNQao=
 github.com/bsm/gomega v1.26.0 h1:LhQm+AFcgV2M0WyKroMASzAzCAJVpAxQXv4SaI9a69Y=
 github.com/btcsuite/btcd v0.20.1-beta/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
@@ -230,6 +232,8 @@ github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaS
 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/golang/snappy v0.0.3/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
@@ -309,6 +313,7 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
 github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 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=
@@ -347,6 +352,8 @@ github.com/mattn/go-isatty v0.0.18 h1:DOKFKCQ7FNG2L1rbrmstDN4QVRdS89Nkh85u68Uwp9
 github.com/mattn/go-isatty v0.0.18/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-runewidth v0.0.13 h1:lTGmDsbAYt5DmK6OnoV7EuIF1wEIFAcxld6ypU4OSgU=
 github.com/mattn/go-runewidth v0.0.13/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zkfA9PSy5pEvNWRP0ET0TIVo=
+github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
 github.com/mitchellh/copystructure v1.0.0 h1:Laisrj+bAB6b/yJwB5Bt3ITZhGJdqmxquMKeZ+mmkFQ=
 github.com/mitchellh/copystructure v1.0.0/go.mod h1:SNtv71yrdKgLRyLFxmLdkAbkKEFWgYaq1OVrnRcwhnw=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
@@ -379,6 +386,7 @@ github.com/opencontainers/selinux v1.10.0/go.mod h1:2i0OySw99QjzBBQByd1Gr9gSjvuh
 github.com/ory/dockertest/v3 v3.10.0 h1:4K3z2VMe8Woe++invjaTB7VRyQXQy5UY+loujO4aNE4=
 github.com/ory/dockertest/v3 v3.10.0/go.mod h1:nr57ZbRWMqfsdGdFNLHz5jjNdDb7VVFnzAeW1n5N1Lg=
 github.com/oxtoacart/bpool v0.0.0-20190530202638-03653db5a59c/go.mod h1:X07ZCGwUbLaax7L0S3Tw4hpejzu63ZrrQiUe6W0hcy0=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
@@ -386,7 +394,15 @@ github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pkg/profile v1.6.0/go.mod h1:qBsxPvzyUincmltOk6iyRVxHYg4adc0OFOv72ZdLa18=
 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 v1.16.0 h1:yk/hx9hDbrGHovbci4BY+pRMfSuuat626eFsHb7tmT8=
+github.com/prometheus/client_golang v1.16.0/go.mod h1:Zsulrv/L9oM40tJ7T815tM89lFEugiJ9HzIqaAx4LKc=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/client_model v0.3.0 h1:UBgGFHqYdG/TPFD1B1ogZywDqEkwp3fBMvqdiQ7Xew4=
+github.com/prometheus/client_model v0.3.0/go.mod h1:LDGWKZIo7rky3hgvBe+caln+Dr3dPggB5dvjtD7w9+w=
+github.com/prometheus/common v0.42.0 h1:EKsfXEYo4JpWMHH5cg+KOUWeuJSov1Id8zGR8eeI1YM=
+github.com/prometheus/common v0.42.0/go.mod h1:xBwqVerjNdUDjgODMpudtOMwlOwf2SaTr1yjz4b7Zbc=
+github.com/prometheus/procfs v0.10.1 h1:kYK1Va/YMlutzCGazswoHKo//tZVlFpKYh+PymziUAg=
+github.com/prometheus/procfs v0.10.1/go.mod h1:nwNm2aOCAYw8uTR/9bWRREkZFxAUcWzPHWJq+XBB/FM=
 github.com/qri-io/jsonpointer v0.1.1 h1:prVZBZLL6TW5vsSB9fFHFAMBLI4b0ri5vribQlTJiBA=
 github.com/qri-io/jsonpointer v0.1.1/go.mod h1:DnJPaYgiKu56EuDp8TU5wFLdZIcAnb/uH9v37ZaMV64=
 github.com/qri-io/jsonschema v0.2.1 h1:NNFoKms+kut6ABPf6xiKNM5214jzxAhDBrPHCJ97Wg0=
@@ -398,6 +414,7 @@ github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
 github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
@@ -665,6 +682,8 @@ golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.7.0 h1:3jlCCIQZPdOYu1h8BkNvLz8Kgwtae2cagcG/VamtZRU=
 golang.org/x/sys v0.7.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.8.0 h1:EBmGv8NaZBZTWvrbjNoL6HVt+IVy3QDQpJs7VRIw3tU=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 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 v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
@@ -891,6 +910,8 @@ google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp0
 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 v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 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 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=

internal/admin/server.go

@@ -16,6 +16,7 @@ import (
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/go-chi/cors"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"gitlab.com/wpetit/goweb/logger"
 )
 
@@ -101,6 +102,25 @@ func (s *Server) run(parentCtx context.Context, addrs chan net.Addr, errs chan e
 
 	router.Use(corsMiddleware.Handler)
 
+	if s.serverConfig.Metrics.Enabled {
+		metrics := s.serverConfig.Metrics
+
+		logger.Info(ctx, "enabling metrics", logger.F("endpoint", metrics.Endpoint))
+
+		router.Group(func(r chi.Router) {
+			if metrics.BasicAuth != nil {
+				logger.Info(ctx, "enabling authentication on metrics endpoint")
+
+				r.Use(middleware.BasicAuth(
+					"metrics",
+					metrics.BasicAuth.CredentialsMap(),
+				))
+			}
+
+			r.Handle(string(metrics.Endpoint), promhttp.Handler())
+		})
+	}
+
 	router.Route("/api/v1", func(r chi.Router) {
 		r.Group(func(r chi.Router) {
 			r.Use(auth.Middleware(

internal/command/common/load_config.go

@@ -4,7 +4,6 @@ import (
 	"forge.cadoles.com/cadoles/bouncer/internal/config"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli/v2"
-	"gitlab.com/wpetit/goweb/logger"
 )
 
 func LoadConfig(ctx *cli.Context) (*config.Config, error) {
@@ -16,15 +15,11 @@ func LoadConfig(ctx *cli.Context) (*config.Config, error) {
 	)
 
 	if configFile != "" {
-		logger.Info(ctx.Context, "loading config", logger.F("config", configFile))
-
 		conf, err = config.NewFromFile(configFile)
 		if err != nil {
 			return nil, errors.Wrapf(err, "Could not load config file '%s'", configFile)
 		}
 	} else {
-		logger.Info(ctx.Context, "using default config")
-
 		conf = config.NewDefault()
 	}
 

internal/command/config/dump.go

@@ -18,6 +18,8 @@ func Dump() *cli.Command {
 		Usage: "Dump the current configuration",
 		Flags: flags,
 		Action: func(ctx *cli.Context) error {
+			logger.SetLevel(logger.LevelError)
+
 			conf, err := common.LoadConfig(ctx)
 			if err != nil {
 				return errors.Wrap(err, "Could not load configuration")

internal/config/admin_server.go

@@ -4,6 +4,7 @@ type AdminServerConfig struct {
 	HTTP    HTTPConfig    `yaml:"http"`
 	CORS    CORSConfig    `yaml:"cors"`
 	Auth    AuthConfig    `yaml:"auth"`
+	Metrics MetricsConfig `yaml:"metrics"`
 }
 
 func NewDefaultAdminServerConfig() AdminServerConfig {
@@ -11,6 +12,7 @@ func NewDefaultAdminServerConfig() AdminServerConfig {
 		HTTP:    NewHTTPConfig("127.0.0.1", 8081),
 		CORS:    NewDefaultCORSConfig(),
 		Auth:    NewDefaultAuthConfig(),
+		Metrics: NewDefaultMetricsConfig(),
 	}
 }
 

internal/config/logger.go

@@ -9,7 +9,7 @@ type LoggerConfig struct {
 
 func NewDefaultLoggerConfig() LoggerConfig {
 	return LoggerConfig{
-		Level:  InterpolatedInt(logger.LevelInfo),
+		Level:  InterpolatedInt(logger.LevelError),
 		Format: InterpolatedString(logger.FormatHuman),
 	}
 }

internal/config/metrics.go

@@ -0,0 +1,35 @@
+package config
+
+import "fmt"
+
+type MetricsConfig struct {
+	Enabled   InterpolatedBool   `yaml:"enabled"`
+	Endpoint  InterpolatedString `yaml:"endpoint"`
+	BasicAuth *BasicAuthConfig   `yaml:"basicAuth"`
+}
+
+type BasicAuthConfig struct {
+	Credentials *InterpolatedMap `yaml:"credentials"`
+}
+
+func (c *BasicAuthConfig) CredentialsMap() map[string]string {
+	if c.Credentials == nil {
+		return map[string]string{}
+	}
+
+	credentials := make(map[string]string, len(*c.Credentials))
+
+	for k, v := range *c.Credentials {
+		credentials[k] = fmt.Sprintf("%v", v)
+	}
+
+	return credentials
+}
+
+func NewDefaultMetricsConfig() MetricsConfig {
+	return MetricsConfig{
+		Enabled:   true,
+		Endpoint:  "/.bouncer/metrics",
+		BasicAuth: nil,
+	}
+}

internal/config/proxy_server.go

@@ -2,10 +2,12 @@ package config
 
 type ProxyServerConfig struct {
 	HTTP    HTTPConfig    `yaml:"http"`
+	Metrics MetricsConfig `yaml:"metrics"`
 }
 
 func NewDefaultProxyServerConfig() ProxyServerConfig {
 	return ProxyServerConfig{
 		HTTP:    NewHTTPConfig("0.0.0.0", 8080),
+		Metrics: NewDefaultMetricsConfig(),
 	}
 }

internal/proxy/director/director.go

@@ -10,6 +10,7 @@ import (
 	"forge.cadoles.com/Cadoles/go-proxy/wildcard"
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
 	"gitlab.com/wpetit/goweb/logger"
 )
 
@@ -59,6 +60,8 @@ MAIN:
 		logger.F("remoteAddr", r.RemoteAddr),
 	)
 
+	metricProxyRequestsTotal.With(prometheus.Labels{metricLabelProxy: string(match.Name)}).Add(1)
+
 	ctx = withProxy(ctx, match)
 
 	layers, err := d.getLayers(ctx, match.Name)

internal/proxy/director/layer/queue/debouncer.go

@@ -0,0 +1,73 @@
+package queue
+
+import (
+	"sync"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+type DebouncerMap struct {
+	debouncers sync.Map
+}
+
+func NewDebouncerMap() *DebouncerMap {
+	return &DebouncerMap{
+		debouncers: sync.Map{},
+	}
+}
+
+func (m *DebouncerMap) Do(key string, after time.Duration, fn func()) {
+	newDebouncer := NewDebouncer(after)
+	rawDebouncer, loaded := m.debouncers.LoadOrStore(key, newDebouncer)
+
+	debouncer, ok := rawDebouncer.(*Debouncer)
+	if !ok {
+		panic(errors.Errorf("unexpected debouncer value, expected '%T', got '%T'", newDebouncer, rawDebouncer))
+	}
+
+	if loaded {
+		debouncer.Update(after)
+	}
+
+	debouncer.Do(fn)
+}
+
+func NewDebouncer(after time.Duration) *Debouncer {
+	return &Debouncer{after: after}
+}
+
+type Debouncer struct {
+	mu    sync.Mutex
+	after time.Duration
+	timer *time.Timer
+	fn    func()
+}
+
+func (d *Debouncer) Do(fn func()) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if d.timer != nil {
+		d.timer.Stop()
+	}
+
+	d.fn = fn
+	d.timer = time.AfterFunc(d.after, d.fn)
+}
+
+func (d *Debouncer) Update(after time.Duration) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if after == d.after {
+		return
+	}
+
+	if d.timer != nil {
+		d.timer.Stop()
+	}
+
+	d.after = after
+	d.timer = time.AfterFunc(d.after, d.fn)
+}

internal/proxy/director/layer/queue/metrics.go

@@ -0,0 +1,31 @@
+package queue
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+const (
+	metricNamespace  = "bouncer_layer_queue"
+	metricLabelProxy = "proxy"
+	metricLabelLayer = "layer"
+)
+
+var (
+	metricQueueSessions = promauto.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name:      "sessions",
+			Help:      "Bouncer's queue layer current sessions",
+			Namespace: metricNamespace,
+		},
+		[]string{metricLabelProxy, metricLabelLayer},
+	)
+	metricQueueCapacity = promauto.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name:      "capacity",
+			Help:      "Bouncer's queue layer capacity",
+			Namespace: metricNamespace,
+		},
+		[]string{metricLabelProxy, metricLabelLayer},
+	)
+)

internal/proxy/director/layer/queue/queue.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"html/template"
+	"math/rand"
 	"net/http"
 	"path/filepath"
 	"sync"
@@ -16,6 +17,7 @@ import (
 	"github.com/Masterminds/sprig/v3"
 	"github.com/google/uuid"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
 	"gitlab.com/wpetit/goweb/logger"
 )
 
@@ -31,6 +33,8 @@ type Queue struct {
 	tmpl        *template.Template
 
 	refreshJobRunning       uint32
+	updateMetricsJobRunning uint32
+	postKeepAliveDebouncer  *DebouncerMap
 }
 
 // LayerType implements director.MiddlewareLayer
@@ -52,6 +56,8 @@ func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
 				return
 			}
 
+			defer q.updateMetrics(ctx, layer.Proxy, layer.Name, options)
+
 			cookieName := q.getCookieName(layer.Name)
 
 			cookie, err := r.Cookie(cookieName)
@@ -72,8 +78,6 @@ func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
 			sessionID := cookie.Value
 			queueName := string(layer.Name)
 
-			q.refreshQueue(queueName, options.KeepAlive)
-
 			rank, err := q.adapter.Touch(ctx, queueName, sessionID)
 			if err != nil {
 				logger.Error(ctx, "could not retrieve session rank", logger.E(errors.WithStack(err)))
@@ -102,6 +106,30 @@ func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
 	}
 }
 
+func (q *Queue) updateSessionsMetric(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName) {
+	if !atomic.CompareAndSwapUint32(&q.updateMetricsJobRunning, 0, 1) {
+		return
+	}
+
+	defer atomic.StoreUint32(&q.updateMetricsJobRunning, 0)
+
+	queueName := string(layerName)
+
+	status, err := q.adapter.Status(ctx, queueName)
+	if err != nil {
+		logger.Error(ctx, "could not retrieve queue status", logger.E(errors.WithStack(err)))
+
+		return
+	}
+
+	metricQueueSessions.With(
+		prometheus.Labels{
+			metricLabelLayer: string(layerName),
+			metricLabelProxy: string(proxyName),
+		},
+	).Set(float64(status.Sessions))
+}
+
 func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueName string, options *LayerOptions, rank int64) {
 	ctx := r.Context()
 
@@ -135,20 +163,22 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 		return
 	}
 
+	refreshRate := time.Duration(int64(options.KeepAlive.Seconds()/2)) * time.Second
+
 	templateData := struct {
 		QueueName       string
 		LayerOptions    *LayerOptions
 		Rank            int64
 		CurrentSessions int64
 		MaxSessions     int64
-		RefreshRate     int64
+		RefreshRate     time.Duration
 	}{
 		QueueName:       queueName,
 		LayerOptions:    options,
 		Rank:            rank + 1,
 		CurrentSessions: status.Sessions,
 		MaxSessions:     options.Capacity,
-		RefreshRate:     5,
+		RefreshRate:     refreshRate,
 	}
 
 	w.WriteHeader(http.StatusServiceUnavailable)
@@ -161,24 +191,55 @@ func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueNam
 	}
 }
 
-func (q *Queue) refreshQueue(queueName string, keepAlive time.Duration) {
+func (q *Queue) refreshQueue(ctx context.Context, layerName store.LayerName, keepAlive time.Duration) {
 	if !atomic.CompareAndSwapUint32(&q.refreshJobRunning, 0, 1) {
 		return
 	}
 
-	go func() {
 	defer atomic.StoreUint32(&q.refreshJobRunning, 0)
 
-		ctx, cancel := context.WithTimeout(context.Background(), keepAlive*2)
+	if err := q.adapter.Refresh(ctx, string(layerName), keepAlive); err != nil {
-		defer cancel()
-
-		if err := q.adapter.Refresh(ctx, queueName, keepAlive); err != nil {
 		logger.Error(ctx, "could not refresh queue",
 			logger.E(errors.WithStack(err)),
-				logger.F("queue", queueName),
+			logger.F("queue", layerName),
 		)
 	}
-	}()
+}
+
+func (q *Queue) updateMetrics(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName, options *LayerOptions) {
+	// Update queue capacity metric
+	metricQueueCapacity.With(
+		prometheus.Labels{
+			metricLabelLayer: string(layerName),
+			metricLabelProxy: string(proxyName),
+		},
+	).Set(float64(options.Capacity))
+
+	// Refresh queue data and metrics
+	q.refreshQueue(ctx, layerName, options.KeepAlive)
+	q.updateSessionsMetric(ctx, proxyName, layerName)
+
+	// (Re)schedule an update job after session ttl + semi-random time padding
+	// to update metrics after last session expiration
+	randDuration := rand.Int63n(int64(options.KeepAlive))
+	timePadding := options.KeepAlive/2 + time.Duration(randDuration)
+	after := options.KeepAlive + timePadding
+
+	debouncingKey := fmt.Sprintf("%s/%s", proxyName, layerName)
+
+	q.postKeepAliveDebouncer.Do(debouncingKey, after, func() {
+		ctx := logger.With(
+			context.Background(),
+			logger.F("proxy", proxyName),
+			logger.F("layer", layerName),
+			logger.F("after", after),
+		)
+
+		logger.Info(ctx, "running post keep alive refresh job")
+
+		q.refreshQueue(ctx, layerName, options.KeepAlive)
+		q.updateSessionsMetric(ctx, proxyName, layerName)
+	})
 }
 
 func (q *Queue) getCookieName(layerName store.LayerName) string {
@@ -195,6 +256,7 @@ func New(adapter Adapter, funcs ...OptionFunc) *Queue {
 		adapter:                adapter,
 		templateDir:            opts.TemplateDir,
 		defaultKeepAlive:       opts.DefaultKeepAlive,
+		postKeepAliveDebouncer: NewDebouncerMap(),
 	}
 }
 

internal/proxy/director/metrics.go

@@ -0,0 +1,20 @@
+package director
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+const (
+	metricNamespace  = "bouncer_proxy_director"
+	metricLabelProxy = "proxy"
+)
+
+var metricProxyRequestsTotal = promauto.NewCounterVec(
+	prometheus.CounterOpts{
+		Name:      "proxy_requests_total",
+		Help:      "Bouncer proxy total requests",
+		Namespace: metricNamespace,
+	},
+	[]string{metricLabelProxy},
+)

internal/proxy/server.go

@@ -15,6 +15,7 @@ import (
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"gitlab.com/wpetit/goweb/logger"
 )
 
@@ -84,7 +85,28 @@ func (s *Server) run(parentCtx context.Context, addrs chan net.Addr, errs chan e
 	)
 
 	router.Use(middleware.RequestLogger(bouncerChi.NewLogFormatter()))
-	router.Use(director.Middleware())
+
+	if s.serverConfig.Metrics.Enabled {
+		metrics := s.serverConfig.Metrics
+
+		logger.Info(ctx, "enabling metrics", logger.F("endpoint", metrics.Endpoint))
+
+		router.Group(func(r chi.Router) {
+			if metrics.BasicAuth != nil {
+				logger.Info(ctx, "enabling authentication on metrics endpoint")
+
+				r.Use(middleware.BasicAuth(
+					"metrics",
+					metrics.BasicAuth.CredentialsMap(),
+				))
+			}
+
+			r.Handle(string(metrics.Endpoint), promhttp.Handler())
+		})
+	}
+
+	router.Group(func(r chi.Router) {
+		r.Use(director.Middleware())
 
 		handler := proxy.New(
 			proxy.WithRequestTransformers(
@@ -95,7 +117,8 @@ func (s *Server) run(parentCtx context.Context, addrs chan net.Addr, errs chan e
 			),
 		)
 
-	router.Handle("/*", handler)
+		r.Handle("/*", handler)
+	})
 
 	if err := http.Serve(listener, router); err != nil && !errors.Is(err, net.ErrClosed) {
 		errs <- errors.WithStack(err)

layers/queue/templates/queue.gohtml

@@ -5,7 +5,7 @@
         <meta charset="UTF-8">
         <meta name="viewport" content="width=device-width,initial-scale=1">
         <title>Veuillez patienter - {{ .QueueName }}</title>
-        <meta http-equiv="refresh" content="{{ .RefreshRate }}">
+        <meta http-equiv="refresh" content="{{ .RefreshRate.Seconds }}">
         <style>
             html {
               box-sizing: border-box;

modd.conf

@@ -8,8 +8,8 @@ layers/**
     prep: make build-bouncer
     prep: make config.yml
     prep: make .bouncer-token
-    daemon: make run BOUNCER_CMD="--config config.yml server admin run"
+    daemon: make run BOUNCER_CMD="--debug --config config.yml server admin run"
-    daemon: make run BOUNCER_CMD="--config config.yml server proxy run"
+    daemon: make run BOUNCER_CMD="--debug --config config.yml server proxy run"
 }
 
 {