feat: add basic prometheus metrics integration

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,
+	}
+}