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/secrets/health.go

@@ -0,0 +1,5 @@
+package secrets
+
+import "github.com/qdm12/gluetun/internal/configuration/settings"
+
+func (r *Reader) ReadHealth() (settings settings.Health, err error) { return settings, nil }

internal/configuration/sources/secrets/helpers.go

@@ -0,0 +1,31 @@
+package secrets
+
+import (
+	"os"
+
+	"github.com/qdm12/gluetun/internal/configuration/sources/files"
+)
+
+func readSecretFileAsStringPtr(secretPathEnvKey, defaultSecretPath string) (
+	stringPtr *string, err error) {
+	path := os.Getenv(secretPathEnvKey)
+	if path == "" {
+		path = defaultSecretPath
+	}
+	return files.ReadFromFile(path)
+}
+
+func readSecretFileAsString(secretPathEnvKey, defaultSecretPath string) (
+	s string, err error) {
+	path := os.Getenv(secretPathEnvKey)
+	if path == "" {
+		path = defaultSecretPath
+	}
+	stringPtr, err := files.ReadFromFile(path)
+	if err != nil {
+		return "", err
+	} else if stringPtr == nil {
+		return "", nil
+	}
+	return *stringPtr, nil
+}

internal/configuration/sources/secrets/httpproxy.go

@@ -0,0 +1,27 @@
+package secrets
+
+import (
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+)
+
+func readHTTPProxy() (settings settings.HTTPProxy, err error) {
+	settings.User, err = readSecretFileAsStringPtr(
+		"HTTPPROXY_USER_SECRETFILE",
+		"/run/secrets/httpproxy_user",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read HTTP proxy user secret file: %w", err)
+	}
+
+	settings.Password, err = readSecretFileAsStringPtr(
+		"HTTPPROXY_PASSWORD_SECRETFILE",
+		"/run/secrets/httpproxy_password",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read OpenVPN password secret file: %w", err)
+	}
+
+	return settings, nil
+}

internal/configuration/sources/secrets/openvpn.go

@@ -0,0 +1,44 @@
+package secrets
+
+import (
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+)
+
+func readOpenVPN() (
+	settings settings.OpenVPN, err error) {
+	settings.User, err = readSecretFileAsString(
+		"OPENVPN_USER_SECRETFILE",
+		"/run/secrets/openvpn_user",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read user file: %w", err)
+	}
+
+	settings.Password, err = readSecretFileAsString(
+		"OPENVPN_PASSWORD_SECRETFILE",
+		"/run/secrets/openvpn_password",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read password file: %w", err)
+	}
+
+	settings.ClientKey, err = readSecretFileAsStringPtr(
+		"OPENVPN_CLIENTKEY_SECRETFILE",
+		"/run/secrets/openvpn_clientkey",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read client key file: %w", err)
+	}
+
+	settings.ClientCrt, err = readSecretFileAsStringPtr(
+		"OPENVPN_CLIENTCRT_SECRETFILE",
+		"/run/secrets/openvpn_clientcrt",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read client certificate file: %w", err)
+	}
+
+	return settings, nil
+}

internal/configuration/sources/secrets/reader.go

@@ -0,0 +1,34 @@
+package secrets
+
+import (
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+	"github.com/qdm12/gluetun/internal/configuration/sources"
+)
+
+var _ sources.Source = (*Reader)(nil)
+
+type Reader struct {
+}
+
+func New() *Reader {
+	return &Reader{}
+}
+
+func (r *Reader) Read() (settings settings.Settings, err error) {
+	settings.VPN, err = readVPN()
+	if err != nil {
+		return settings, err
+	}
+
+	settings.HTTPProxy, err = readHTTPProxy()
+	if err != nil {
+		return settings, err
+	}
+
+	settings.Shadowsocks, err = readShadowsocks()
+	if err != nil {
+		return settings, err
+	}
+
+	return settings, nil
+}

internal/configuration/sources/secrets/shadowsocks.go

@@ -0,0 +1,19 @@
+package secrets
+
+import (
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+)
+
+func readShadowsocks() (settings settings.Shadowsocks, err error) {
+	settings.Password, err = readSecretFileAsStringPtr(
+		"SHADOWSOCKS_PASSWORD_SECRETFILE",
+		"/run/secrets/shadowsocks_password",
+	)
+	if err != nil {
+		return settings, fmt.Errorf("cannot read Shadowsocks password secret file: %w", err)
+	}
+
+	return settings, nil
+}

internal/configuration/sources/secrets/vpn.go

@@ -0,0 +1,16 @@
+package secrets
+
+import (
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+)
+
+func readVPN() (vpn settings.VPN, err error) {
+	vpn.OpenVPN, err = readOpenVPN()
+	if err != nil {
+		return vpn, fmt.Errorf("cannot read OpenVPN settings: %w", err)
+	}
+
+	return vpn, nil
+}