chore(settings): refactor settings processing (#756)

- Better settings tree structure logged using `qdm12/gotree`
- Read settings from environment variables, then files, then secret files
- Settings methods to default them, merge them and override them
- `DNS_PLAINTEXT_ADDRESS` default changed to `127.0.0.1` to use DoT. Warning added if set to something else.
- `HTTPPROXY_LISTENING_ADDRESS` instead of `HTTPPROXY_PORT` (with retro-compatibility)

internal/configuration/sources/env/httproxy.go

@@ -0,0 +1,186 @@
+package env
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+	"github.com/qdm12/govalid/binary"
+)
+
+func (r *Reader) readHTTPProxy() (httpProxy settings.HTTPProxy, err error) {
+	httpProxy.User = r.readHTTProxyUser()
+	httpProxy.Password = r.readHTTProxyPassword()
+	httpProxy.ListeningAddress = r.readHTTProxyListeningAddress()
+
+	httpProxy.Enabled, err = r.readHTTProxyEnabled()
+	if err != nil {
+		return httpProxy, err
+	}
+
+	httpProxy.Stealth, err = envToBoolPtr("HTTPPROXY_STEALTH")
+	if err != nil {
+		return httpProxy, fmt.Errorf("environment variable HTTPPROXY_STEALTH: %w", err)
+	}
+
+	httpProxy.Log, err = r.readHTTProxyLog()
+	if err != nil {
+		return httpProxy, err
+	}
+
+	return httpProxy, nil
+}
+
+func (r *Reader) readHTTProxyUser() (user *string) {
+	s := os.Getenv("HTTPPROXY_USER")
+	if s != "" {
+		return &s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("TINYPROXY_USER")
+	if s != "" {
+		r.onRetroActive("TINYPROXY_USER", "HTTPPROXY_USER")
+		return &s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("PROXY_USER")
+	if s != "" {
+		r.onRetroActive("PROXY_USER", "HTTPPROXY_USER")
+		return &s
+	}
+
+	return nil
+}
+
+func (r *Reader) readHTTProxyPassword() (user *string) {
+	s := os.Getenv("HTTPPROXY_PASSWORD")
+	if s != "" {
+		return &s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("TINYPROXY_PASSWORD")
+	if s != "" {
+		r.onRetroActive("TINYPROXY_PASSWORD", "HTTPPROXY_PASSWORD")
+		return &s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("PROXY_PASSWORD")
+	if s != "" {
+		r.onRetroActive("PROXY_PASSWORD", "HTTPPROXY_PASSWORD")
+		return &s
+	}
+
+	return nil
+}
+
+func (r *Reader) readHTTProxyListeningAddress() (listeningAddress string) {
+	s := os.Getenv("HTTPPROXY_LISTENING_ADDRESS")
+	if s != "" {
+		return s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("HTTPPROXY_PORT")
+	if s != "" {
+		r.onRetroActive("HTTPPROXY_PORT", "HTTPPROXY_LISTENING_ADDRESS")
+		return ":" + s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("TINYPROXY_PORT")
+	if s != "" {
+		r.onRetroActive("TINYPROXY_PORT", "HTTPPROXY_LISTENING_ADDRESS")
+		return ":" + s
+	}
+
+	// Retro-compatibility
+	s = os.Getenv("PROXY_PORT")
+	if s != "" {
+		r.onRetroActive("PROXY_PORT", "HTTPPROXY_LISTENING_ADDRESS")
+		return ":" + s
+	}
+
+	return ""
+}
+
+func (r *Reader) readHTTProxyEnabled() (enabled *bool, err error) {
+	s := strings.ToLower(os.Getenv("HTTPPROXY"))
+	if s != "" {
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable HTTPPROXY: %w", err)
+		}
+		return enabled, nil
+	}
+
+	// Retro-compatibility
+	s = strings.ToLower(os.Getenv("TINYPROXY"))
+	if s != "" {
+		r.onRetroActive("TINYPROXY", "HTTPPROXY")
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable TINYPROXY: %w", err)
+		}
+		return enabled, nil
+	}
+
+	// Retro-compatibility
+	s = strings.ToLower(os.Getenv("PROXY"))
+	if s != "" {
+		r.onRetroActive("PROXY", "HTTPPROXY")
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable PROXY: %w", err)
+		}
+		return enabled, nil
+	}
+
+	return nil, nil //nolint:nilnil
+}
+
+func (r *Reader) readHTTProxyLog() (enabled *bool, err error) {
+	s := strings.ToLower(os.Getenv("HTTPPROXY_LOG"))
+	if s != "" {
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable HTTPPROXY_LOG: %w", err)
+		}
+		return enabled, nil
+	}
+
+	// Retro-compatibility
+	retroOption := binary.OptionEnabled("on", "info", "connect", "notice")
+	s = strings.ToLower(os.Getenv("TINYPROXY_LOG"))
+	if s != "" {
+		r.onRetroActive("TINYPROXY_LOG", "HTTPPROXY_LOG")
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s, retroOption)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable TINYPROXY_LOG: %w", err)
+		}
+		return enabled, nil
+	}
+
+	// Retro-compatibility
+	s = strings.ToLower(os.Getenv("PROXY_LOG_LEVEL"))
+	if s != "" {
+		r.onRetroActive("PROXY_LOG_LEVEL", "HTTPPROXY_LOG")
+		enabled = new(bool)
+		*enabled, err = binary.Validate(s, retroOption)
+		if err != nil {
+			return nil, fmt.Errorf("environment variable PROXY_LOG_LEVEL: %w", err)
+		}
+		return enabled, nil
+	}
+
+	return nil, nil //nolint:nilnil
+}