feat(config): add metrics bind config to policy file with flag hack

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/config/config.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"errors"
+	"flag"
 	"fmt"
 	"io"
 	"io/fs"
@@ -334,6 +335,7 @@ type fileConfig struct {
 	DNSBL       bool                `json:"dnsbl"`
 	DNSTTL      DnsTTL              `json:"dns_ttl"`
 	Logging     *Logging            `json:"logging"`
+	Metrics     *Metrics            `json:"metrics,omitempty"`
 }
 
 func (c *fileConfig) Valid() error {
@@ -375,6 +377,12 @@ func (c *fileConfig) Valid() error {
 		}
 	}
 
+	if c.Metrics != nil {
+		if err := c.Metrics.Valid(); err != nil {
+			errs = append(errs, err)
+		}
+	}
+
 	if len(errs) != 0 {
 		return fmt.Errorf("config is not valid:\n%w", errors.Join(errs...))
 	}
@@ -382,6 +390,16 @@ func (c *fileConfig) Valid() error {
 	return nil
 }
 
+func flagLookup(name string) string {
+	fl := flag.CommandLine.Lookup(name)
+
+	if fl == nil {
+		return ""
+	}
+
+	return fl.Value.String()
+}
+
 func Load(fin io.Reader, fname string) (*Config, error) {
 	c := &fileConfig{
 		StatusCodes: StatusCodes{
@@ -396,6 +414,10 @@ func Load(fin io.Reader, fname string) (*Config, error) {
 			Backend: "memory",
 		},
 		Logging: (Logging{}).Default(),
+		Metrics: &Metrics{
+			Bind:    flagLookup("metrics-bind"),
+			Network: flagLookup("metrics-bind-network"),
+		},
 	}
 
 	if err := yaml.NewYAMLToJSONDecoder(fin).Decode(&c); err != nil {
@@ -417,6 +439,7 @@ func Load(fin io.Reader, fname string) (*Config, error) {
 		StatusCodes: c.StatusCodes,
 		Store:       c.Store,
 		Logging:     c.Logging,
+		Metrics:     c.Metrics,
 	}
 
 	if c.OpenGraph.TimeToLive != "" {
@@ -508,6 +531,7 @@ type Config struct {
 	Logging     *Logging
 	DNSBL       bool
 	DNSTTL      DnsTTL
+	Metrics     *Metrics
 }
 
 func (c Config) Valid() error {