Read every setting through viper (closes #211)

servewaf's and rproxy's settings are read through viper, bound to the same environment variable names as before, in place of the os.LookupEnv function Main passed down. NewViper turns AutomaticEnv and AllowEmptyEnv on, so a setting that is set but empty reads as set, as it did. The _FILE forms, their errors, and rproxy reading no file form are unchanged, and the settings tests pass set into a viper instead of a lookup function.

Model: deepseek-v4-pro

internal/servewaf/proxy_test.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
@@ -347,6 +349,17 @@ func serve(t *testing.T, server *servewaf.Server) {
 // at serveWAFAddr, with the settings in env on top of the defaults, and returns
 // where it listens. What it writes is dropped. SWRP_TIMEOUT_MS is a minute unless
 // env sets it, so that on a busy host SWRP_DEFAULT_DISPOSITION does not decide.
+// viperFrom returns a viper Set with each of settings, as the viper
+// config.NewViper returns one bound to a process's environment.
+func viperFrom(settings map[string]string) *viper.Viper {
+	v := viper.New()
+	for name, value := range settings {
+		v.Set(name, value)
+	}
+
+	return v
+}
+
 func startRProxy(
 	t *testing.T, serveWAFAddr, appURL string, env map[string]string,
 ) string {
@@ -359,11 +372,7 @@ func startRProxy(
 	}
 	maps.Copy(settings, env)
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
-		value, ok := settings[name]
-
-		return value, ok
-	})
+	cfg, err := config.RProxyFromEnvironment(viperFrom(settings))
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}
@@ -423,11 +432,7 @@ func newServeWAFWith(
 
 	maps.Copy(settings, env)
 
-	cfg, err := config.FromEnvironment(func(name string) (string, bool) {
-		value, ok := settings[name]
-
-		return value, ok
-	})
+	cfg, err := config.FromEnvironment(viperFrom(settings))
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}