config: add security and performance sections to sample config; validate

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ieda42bcbd09014c45fb14bee579f829c6a6a6964

config.example.yaml

@@ -8,13 +8,18 @@ site:
   # Options: "daily", "hourly"
   salt_rotation: "daily"
 
+  # Sampling rate (0.0 to 1.0, default: 1.0 = 100%)
+  # Use 0.1 to track 10% of traffic for high-volume sites
+  sampling: 1.0
+
   # Which dimensions to collect
   collect:
     pageviews: true
     country: true
     device: true
-    # Referrer collection mode: "off", "domain"
+    # Referrer collection mode: "off", "domain", "url"
     # "domain" - collect only the domain part (e.g., "google.com")
+    # "url" - collect full URL (not recommended - high cardinality)
     # "off" - don't collect referrer data
     referrer: "domain"
 
@@ -32,7 +37,7 @@ site:
     strip_fragment: true
     # Collapse numeric segments to :id (e.g., /user/123 -> /user/:id)
     collapse_numeric_segments: true
-    # Maximum number of path segments to keep
+    # Maximum number of path segments to keep (0 = unlimited)
     max_segments: 5
     # Normalize trailing slashes (e.g., /page/ -> /page)
     normalize_trailing_slash: true
@@ -43,8 +48,36 @@ limits:
   max_paths: 10000
   # Maximum number of unique referrer sources to track
   max_sources: 500
-  # Maximum events per minute (for rate limiting, not yet implemented)
-  max_events_per_minute: 1000
+  # Maximum number of unique custom event names to track
+  max_custom_events: 100
+  # Maximum events per minute (rate limiting, 0 = unlimited)
+  max_events_per_minute: 10000
+
+  # Device classification breakpoints (screen width in pixels)
+  device_breakpoints:
+    mobile: 768  # < 768px = mobile
+    tablet: 1024 # < 1024px = tablet, >= 1024px = desktop
+
+# Security settings
+security:
+  # Trusted proxy IPs/CIDRs - only trust X-Forwarded-For from these IPs
+  # Leave empty to never trust proxy headers
+  trusted_proxies:
+    - "127.0.0.1"
+    - "10.0.0.0/8"
+    # - "your-load-balancer-ip"
+
+  # CORS configuration for cross-origin tracking
+  cors:
+    enabled: false
+    allowed_origins:
+      - "*"  # Or specific domains: ["https://example.com", "https://www.example.com"]
+
+  # Basic authentication for /metrics endpoint
+  metrics_auth:
+    enabled: false
+    username: "admin"
+    password: "changeme"
 
 # Server configuration
 server:

internal/config/config.go

@@ -12,6 +12,7 @@ type Config struct {
 	Site     SiteConfig     `yaml:"site"`
 	Limits   LimitsConfig   `yaml:"limits"`
 	Server   ServerConfig   `yaml:"server"`
+	Security SecurityConfig `yaml:"security"`
 }
 
 // Site-specific settings
@@ -21,6 +22,7 @@ type SiteConfig struct {
 	Collect      CollectConfig `yaml:"collect"`
 	CustomEvents []string      `yaml:"custom_events"`
 	Path         PathConfig    `yaml:"path"`
+	Sampling     float64       `yaml:"sampling"` // 0.0-1.0, 1.0 = track all traffic
 }
 
 // Which dimensions to collect
@@ -45,6 +47,34 @@ type LimitsConfig struct {
 	MaxPaths           int          `yaml:"max_paths"`
 	MaxEventsPerMinute int          `yaml:"max_events_per_minute"`
 	MaxSources         int          `yaml:"max_sources"`
+	MaxCustomEvents    int          `yaml:"max_custom_events"`
+	DeviceBreakpoints  DeviceBreaks `yaml:"device_breakpoints"`
+}
+
+// Device classification breakpoints
+type DeviceBreaks struct {
+	Mobile int `yaml:"mobile"` // < mobile = mobile
+	Tablet int `yaml:"tablet"` // < tablet = tablet, else desktop
+}
+
+// Security settings
+type SecurityConfig struct {
+	TrustedProxies []string   `yaml:"trusted_proxies"` // IPs/CIDRs to trust X-Forwarded-For from
+	CORS           CORSConfig `yaml:"cors"`
+	MetricsAuth    AuthConfig `yaml:"metrics_auth"`
+}
+
+// CORS configuration
+type CORSConfig struct {
+	Enabled        bool     `yaml:"enabled"`
+	AllowedOrigins []string `yaml:"allowed_origins"` // ["*"] or specific domains
+}
+
+// Authentication for metrics endpoint
+type AuthConfig struct {
+	Enabled  bool   `yaml:"enabled"`
+	Username string `yaml:"username"`
+	Password string `yaml:"password"`
 }
 
 // Server endpoints
@@ -74,29 +104,61 @@ func Load(path string) (*Config, error) {
 }
 
 // Check required fields and sets defaults
-// FIXME: in the future we need to validate in the config parser
 func (c *Config) Validate() error {
-	// Validate site domain is required
+	// Site validation
 	if c.Site.Domain == "" {
 		return fmt.Errorf("site.domain is required")
 	}
 
-	// Validate salt_rotation if provided
+	// Validate salt_rotation
 	if c.Site.SaltRotation != "" && c.Site.SaltRotation != "daily" && c.Site.SaltRotation != "hourly" {
 		return fmt.Errorf("site.salt_rotation must be 'daily' or 'hourly'")
 	}
 
-	// Validate max_paths is positive
+	// Validate referrer setting
+	if c.Site.Collect.Referrer != "" && c.Site.Collect.Referrer != "off" &&
+		c.Site.Collect.Referrer != "domain" && c.Site.Collect.Referrer != "url" {
+		return fmt.Errorf("site.collect.referrer must be 'off', 'domain', or 'url'")
+	}
+
+	// Validate sampling rate
+	if c.Site.Sampling < 0.0 || c.Site.Sampling > 1.0 {
+		return fmt.Errorf("site.sampling must be between 0.0 and 1.0")
+	}
+	if c.Site.Sampling == 0.0 {
+		c.Site.Sampling = 1.0 // default to 100%
+	}
+
+	// Limits validation
 	if c.Limits.MaxPaths <= 0 {
 		return fmt.Errorf("limits.max_paths must be greater than 0")
 	}
 
-	// Validate max_sources is positive
 	if c.Limits.MaxSources <= 0 {
 		return fmt.Errorf("limits.max_sources must be greater than 0")
 	}
 
-	// Set server defaults if not provided
+	if c.Limits.MaxEventsPerMinute < 0 {
+		return fmt.Errorf("limits.max_events_per_minute cannot be negative")
+	}
+
+	if c.Limits.MaxCustomEvents <= 0 {
+		c.Limits.MaxCustomEvents = 100 // Default
+	}
+
+	if c.Site.Path.MaxSegments < 0 {
+		return fmt.Errorf("site.path.max_segments cannot be negative")
+	}
+
+	// Set device breakpoint defaults
+	if c.Limits.DeviceBreakpoints.Mobile == 0 {
+		c.Limits.DeviceBreakpoints.Mobile = 768
+	}
+	if c.Limits.DeviceBreakpoints.Tablet == 0 {
+		c.Limits.DeviceBreakpoints.Tablet = 1024
+	}
+
+	// Server defaults
 	if c.Server.ListenAddr == "" {
 		c.Server.ListenAddr = ":8080"
 	}
@@ -107,5 +169,15 @@ func (c *Config) Validate() error {
 		c.Server.IngestionPath = "/api/event"
 	}
 
+	if c.Security.MetricsAuth.Enabled {
+		if c.Security.MetricsAuth.Username == "" || c.Security.MetricsAuth.Password == "" {
+			return fmt.Errorf("security.metrics_auth: username and password required when enabled")
+		}
+	}
+
+	if c.Security.CORS.Enabled && len(c.Security.CORS.AllowedOrigins) == 0 {
+		return fmt.Errorf("security.cors: allowed_origins required when enabled")
+	}
+
 	return nil
 }