main: version flag and optional metrics listener

Dockerfile

@@ -6,7 +6,12 @@ COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
-RUN go install ./...
+
+RUN go build -o /go/bin/webauthn-oidc-idp -ldflags "\
+    -X 'github.com/prometheus/common/version.Branch=$(git describe --contains --all HEAD)' \
+    -X 'github.com/prometheus/common/version.BuildUser=$(whoami)' \
+    -X 'github.com/prometheus/common/version.BuildDate=$(date --iso-8601=seconds)'" \
+    ./...
 
 FROM debian:bookworm
 

e2e_test.go

@@ -101,7 +101,7 @@ func TestE2E(t *testing.T) {
 
 	serveErr := make(chan error, 1)
 	go func() {
-		if err := serve(serveCtx, db, issConfig, net.JoinHostPort("localhost", port)); err != nil {
+		if err := serve(serveCtx, db, issConfig, net.JoinHostPort("localhost", port), ""); err != nil {
 			serveErr <- err
 		}
 	}()

go.mod

@@ -14,12 +14,16 @@ require (
 	github.com/lstoll/oidc v1.0.0-alpha.1
 	github.com/mattn/go-sqlite3 v1.14.13
 	github.com/oklog/run v1.1.0
+	github.com/prometheus/client_golang v1.19.0
+	github.com/prometheus/common v0.50.0
 	github.com/tink-crypto/tink-go/v2 v2.1.0
-	golang.org/x/oauth2 v0.17.0
-	golang.org/x/sys v0.17.0
+	golang.org/x/oauth2 v0.18.0
+	golang.org/x/sys v0.18.0
 )
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/chromedp/sysutil v1.0.0 // indirect
 	github.com/fxamacker/cbor/v2 v2.5.0 // indirect
 	github.com/go-webauthn/x v0.1.8 // indirect
@@ -32,10 +36,12 @@ require (
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/prometheus/client_model v0.6.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	golang.org/x/crypto v0.20.0 // indirect
 	google.golang.org/appengine v1.6.8 // indirect
-	google.golang.org/protobuf v1.32.0 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 )
 
 replace crawshaw.dev/jsonfile => github.com/sr/jsonfile v0.0.0-20240301210704-69e8a5b5b148

go.sum

@@ -1,3 +1,7 @@
+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/chromedp/cdproto v0.0.0-20240202021202-6d0b6a386732 h1:XYUCaZrW8ckGWlCRJKCSoh/iFwlpX316a8yY9IFEzv8=
 github.com/chromedp/cdproto v0.0.0-20240202021202-6d0b6a386732/go.mod h1:GKljq0VrfU4D5yc+2qA6OVr8pmO/MBbPEWqWQ/oqGEs=
 github.com/chromedp/chromedp v0.9.5 h1:viASzruPJOiThk7c5bueOUY91jGLJVximoEMGoH93rg=
@@ -53,6 +57,14 @@ github.com/orisano/pixelmatch v0.0.0-20220722002657-fb0b55479cde h1:x0TT0RDC7UhA
 github.com/orisano/pixelmatch v0.0.0-20220722002657-fb0b55479cde/go.mod h1:nZgzbfBr3hhjoZnS66nKrHmduYNpc34ny7RK4z5/HM0=
 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 v1.19.0 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 v0.6.0 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 v0.12.0 h1:jluTpSng7V9hY0O2R9DzzJHYb2xULk9VTR1V1R/k6Bo=
+github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
 github.com/sr/jsonfile v0.0.0-20240301210704-69e8a5b5b148 h1:gQ7t2Q9iRRtBYAvcszOA9vFGdtW3R/4pT+itPH8b22c=
 github.com/sr/jsonfile v0.0.0-20240301210704-69e8a5b5b148/go.mod h1:rWYpwcta+HEXjFjbDiSFGqzhZ5KPlNhit+irVCFLQAI=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
@@ -70,8 +82,8 @@ golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91
 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/oauth2 v0.17.0 h1:6m3ZPmLEFdVxKKWnKq4VqZ60gutO35zm+zrAHVmHyDQ=
-golang.org/x/oauth2 v0.17.0/go.mod h1:OzPDGQiuQMguemayvdylqddI7qcD9lnSDb+1FiwQ5HA=
+golang.org/x/oauth2 v0.18.0 h1:09qnuIAgzdx1XplqJvW6CQqMCtGZykZWcXzPMPUusvI=
+golang.org/x/oauth2 v0.18.0/go.mod h1:Wf7knwG0MPoWIMMBgFlEaSUDaKskp0dCfrlJRJXbBi8=
 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/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -81,8 +93,8 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-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/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/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -100,7 +112,7 @@ google.golang.org/appengine v1.6.8 h1:IhEN5q69dyKagZPYMSdIjS2HqprW324FRQZJcGqPAs
 google.golang.org/appengine v1.6.8/go.mod h1:1jJ3jBArFh5pcgW8gCtRJnepW8FzD1V44FJffLiz/Ds=
 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 v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
-google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+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/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -24,17 +24,34 @@ import (
 	"github.com/lstoll/oidc/core/staticclients"
 	"github.com/lstoll/oidc/discovery"
 	"github.com/oklog/run"
+	"github.com/prometheus/client_golang/prometheus"
+	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/prometheus/common/version"
 	"github.com/tink-crypto/tink-go/v2/keyset"
 	"golang.org/x/sys/unix"
 )
 
+const progname = "webauthn-oidc-idp"
+
 //go:embed web/public/*
 var staticFiles embed.FS
 
+func init() {
+	if version.Version == "" {
+		version.Version = "devel"
+	}
+	if version.Branch == "" {
+		version.Branch = "unknown"
+	}
+	prometheus.MustRegister(versioncollector.NewCollector(strings.ReplaceAll(progname, "-", "_")))
+}
+
 func main() {
+	ver := flag.Bool("version", false, "Print the version and exit.")
 	debug := flag.Bool("debug", false, "Enable debug logging")
-
 	addr := flag.String("http", "127.0.0.1:8085", "Run the IDP server on the given host:port.")
+	metrics := flag.String("metrics", "", "Expose Prometheus metrics on the given host:port.")
 	configFile := flag.String("config", "config.json", "Path to the config file.")
 	enroll := flag.Bool("enroll", false, "Enroll a user into the system.")
 	email := flag.String("email", "", "Email address for the user.")
@@ -45,6 +62,11 @@ func main() {
 
 	flag.Parse()
 
+	if *ver {
+		fmt.Fprintln(os.Stdout, version.Print(progname))
+		os.Exit(0)
+	}
+
 	b, err := os.ReadFile(*configFile)
 	if err != nil {
 		fatalf("read config file: %v", err)
@@ -134,12 +156,12 @@ func main() {
 
 	issuer := cfg.Issuer[0]
 
-	if err := serve(ctx, db, issuer, *addr); err != nil {
+	if err := serve(ctx, db, issuer, *addr, *metrics); err != nil {
 		fatalf("start server: %v", err)
 	}
 }
 
-func serve(ctx context.Context, db *DB, issuer issuerConfig, addr string) error {
+func serve(ctx context.Context, db *DB, issuer issuerConfig, addr, metrics string) error {
 	ksm, err := NewKeysetManager(db)
 	if err != nil {
 		return fmt.Errorf("creating OIDC keyset manager: %w", err)
@@ -296,6 +318,24 @@ func serve(ctx context.Context, db *DB, issuer issuerConfig, addr string) error
 		_ = hs.Shutdown(ctx)
 	})
 
+	{
+		if metrics != "" {
+			mux := http.NewServeMux()
+			mux.Handle("/metrics", promhttp.Handler())
+			promsrv := &http.Server{Addr: metrics, Handler: mux}
+
+			g.Add(func() error {
+				slog.Info("metrics server listing", slog.String("addr", "http://"+metrics))
+				if err := promsrv.ListenAndServe(); err != nil {
+					return fmt.Errorf("serving metrics: %v", err)
+				}
+				return nil
+			}, func(error) {
+				promsrv.Close()
+			})
+		}
+	}
+
 	return g.Run()
 }
 
@@ -329,12 +369,12 @@ func reloadDB(addr string) {
 }
 
 func fatal(s string) {
-	fmt.Fprintf(os.Stderr, "webauthn-oidc-idp: %s\n", s)
+	fmt.Fprintf(os.Stderr, "%s: %s\n", progname, s)
 	os.Exit(1)
 }
 
 func fatalf(s string, args ...any) {
-	fmt.Fprintf(os.Stderr, fmt.Sprintf("webauthn-oidc-idp: %s\n", s), args...)
+	fmt.Fprintf(os.Stderr, fmt.Sprintf("%s: %s\n", progname, s), args...)
 	os.Exit(1)
 }