feat: add login product metrics

cmd/gateway/main.go

@@ -15,6 +15,7 @@ import (
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/config"
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/db"
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/login"
+	"github.com/SwissDataScienceCenter/renku-gateway/internal/metrics"
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/revproxy"
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/sessions"
 	"github.com/SwissDataScienceCenter/renku-gateway/internal/tokenstore"
@@ -124,7 +125,18 @@ func main() {
 	}
 	revproxy.RegisterHandlers(e, gwMiddlewares...)
 	// Initialize login server
-	loginServer, err := login.NewLoginServer(login.WithConfig(gwConfig.Login), login.WithSessionStore(sessionStore), login.WithTokenStore(tokenStore))
+	loginOptions := []login.LoginServerOption{login.WithConfig(gwConfig.Login), login.WithSessionStore(sessionStore), login.WithTokenStore(tokenStore)}
+
+	if gwConfig.Posthog.Enabled {
+		metricsClient, err := metrics.NewPosthogClient(gwConfig.Posthog.ApiKey, gwConfig.Posthog.Host, gwConfig.Posthog.Environment)
+		if err != nil {
+			slog.Error("posthog client initializtion failed", "error", err)
+			os.Exit(1)
+		}
+		loginOptions = append(loginOptions, login.WithMetricsClient(metricsClient))
+		defer metricsClient.Close()
+	}
+	loginServer, err := login.NewLoginServer(loginOptions...)
 	if err != nil {
 		slog.Error("login handlers initialization failed", "error", err)
 		os.Exit(1)

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0
 	github.com/oapi-codegen/runtime v1.1.1
 	github.com/oklog/ulid/v2 v2.1.0
+	github.com/posthog/posthog-go v1.3.3
 	github.com/redis/go-redis/v9 v9.4.0
 	github.com/spf13/viper v1.18.2
 	github.com/stretchr/testify v1.8.4

go.sum

@@ -151,6 +151,8 @@ github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/posthog/posthog-go v1.3.3 h1:0b1JlfPDMKXGRgbTtqkSG6hsrlj8yW2tv2HS6Dn7wFk=
+github.com/posthog/posthog-go v1.3.3/go.mod h1:uYC2l1Yktc8E+9FAHJ9QZG4vQf/NHJPD800Hsm7DzoM=
 github.com/prometheus/client_golang v1.18.0 h1:HzFfmkOzH5Q8L8G+kSJKUx5dtG87sewO+FoDDqP5Tbk=
 github.com/prometheus/client_golang v1.18.0/go.mod h1:T+GXkCk5wSJyOqMIzVgvvjFDlkOQntgjkJWKrN5txjA=
 github.com/prometheus/client_model v0.5.0 h1:VQw1hfvPvk3Uv6Qf29VrPF32JB6rtbgI6cYPYQjL0Qw=

internal/config/main.go

@@ -8,6 +8,7 @@ type Config struct {
 	Revproxy   RevproxyConfig
 	Login      LoginConfig
 	Redis      RedisConfig
+	Posthog    PosthogConfig
 	Monitoring MonitoringConfig
 }
 

internal/config/other.go

@@ -29,3 +29,10 @@ type RateLimits struct {
 	Rate    float64
 	Burst   int
 }
+
+type PosthogConfig struct {
+	Enabled     bool
+	ApiKey      string
+	Host        string
+	Environment string
+}

internal/login/login_server.go

@@ -15,6 +15,7 @@ type LoginServer struct {
 	providerStore oidc.ClientStore
 	sessions      *sessions.SessionStore
 	tokenStore    models.TokenStoreInterface
+	metricsClient models.MetricsClientInterface
 }
 
 func (l *LoginServer) RegisterHandlers(server *echo.Echo, commonMiddlewares ...echo.MiddlewareFunc) {
@@ -58,6 +59,13 @@ func WithTokenStore(store models.TokenStoreInterface) LoginServerOption {
 	}
 }
 
+func WithMetricsClient(client models.MetricsClientInterface) LoginServerOption {
+	return func(l *LoginServer) error {
+		l.metricsClient = client
+		return nil
+	}
+}
+
 // NewLoginServer creates a new LoginServer that handles the callbacks from oauth2
 // and initiates the login flow for users.
 func NewLoginServer(options ...LoginServerOption) (*LoginServer, error) {

internal/login/login_server_routes.go

@@ -218,6 +218,12 @@ func (l *LoginServer) nextAuthStep(
 		slog.Info("login completed", "requestID", utils.GetRequestID(c), "appRedirectURL", url)
 		// Save the session: ensure we save the session before sending redirects
 		l.sessions.Save(c)
+		// send product metrics
+		if l.metricsClient != nil {
+			if session, err := l.sessions.Get(c); err == nil {
+				l.metricsClient.UserLoggedIn(session.UserID)
+			}
+		}
 		return c.Redirect(http.StatusFound, url)
 	}
 	providerID := session.LoginSequence[0]

internal/metrics/posthog.go

@@ -0,0 +1,40 @@
+package metrics
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+
+	"github.com/posthog/posthog-go"
+)
+
+type PosthogMetricsClient struct {
+	posthogClient posthog.Client
+}
+
+func (p *PosthogMetricsClient) anonymizeUser(userId string) string {
+	hash := md5.Sum([]byte(userId))
+	return hex.EncodeToString(hash[:])
+}
+
+func (p *PosthogMetricsClient) UserLoggedIn(userId string) error {
+	return p.posthogClient.Enqueue(posthog.Capture{DistinctId: p.anonymizeUser(userId), Event: "user_logged_in"})
+}
+
+func (p *PosthogMetricsClient) Close() {
+	p.posthogClient.Close()
+}
+
+func NewPosthogClient(apiKey string, host string, environment string) (*PosthogMetricsClient, error) {
+	client, err := posthog.NewWithConfig(
+		apiKey,
+		posthog.Config{
+			Endpoint:               host,
+			DefaultEventProperties: posthog.Properties{"environment": environment},
+		},
+	)
+	if err != nil {
+		return &PosthogMetricsClient{}, err
+	}
+
+	return &PosthogMetricsClient{posthogClient: client}, nil
+}

internal/models/metrics.go

@@ -0,0 +1,5 @@
+package models
+
+type MetricsClientInterface interface {
+	UserLoggedIn(userId string) error
+}