chore(sources): wrap error with source string

internal/configuration/sources/env/reader.go

@@ -23,6 +23,8 @@ func New(warner Warner) *Reader {
 	}
 }
 
+func (r *Reader) String() string { return "environment variables" }
+
 func (r *Reader) Read() (settings settings.Settings, err error) {
 	settings.VPN, err = r.readVPN()
 	if err != nil {

internal/configuration/sources/files/reader.go

@@ -13,6 +13,8 @@ func New() *Reader {
 	return &Reader{}
 }
 
+func (r *Reader) String() string { return "files" }
+
 func (r *Reader) Read() (settings settings.Settings, err error) {
 	settings.VPN, err = r.readVPN()
 	if err != nil {

internal/configuration/sources/mux/reader.go

@@ -2,6 +2,7 @@ package mux
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 	"github.com/qdm12/gluetun/internal/configuration/sources"
@@ -19,6 +20,14 @@ func New(sources ...sources.Source) *Reader {
 	}
 }
 
+func (r *Reader) String() string {
+	sources := make([]string, len(r.sources))
+	for i := range r.sources {
+		sources[i] = r.sources[i].String()
+	}
+	return strings.Join(sources, ", ")
+}
+
 // Read reads the settings for each source, merging unset fields
 // with field set by the next source.
 // It then set defaults to remaining unset fields.
@@ -26,7 +35,7 @@ func (r *Reader) Read() (settings settings.Settings, err error) {
 	for _, source := range r.sources {
 		settingsFromSource, err := source.Read()
 		if err != nil {
-			return settings, fmt.Errorf("reading from source %T: %w", source, err)
+			return settings, fmt.Errorf("reading from %s: %w", source, err)
 		}
 		settings.MergeWith(settingsFromSource)
 	}
@@ -42,7 +51,7 @@ func (r *Reader) ReadHealth() (settings settings.Health, err error) {
 	for _, source := range r.sources {
 		settingsFromSource, err := source.ReadHealth()
 		if err != nil {
-			return settings, fmt.Errorf("reading from source %T: %w", source, err)
+			return settings, fmt.Errorf("reading from %s: %w", source, err)
 		}
 		settings.MergeWith(settingsFromSource)
 	}

internal/configuration/sources/secrets/reader.go

@@ -14,6 +14,8 @@ func New() *Reader {
 	return &Reader{}
 }
 
+func (r *Reader) String() string { return "secret files" }
+
 func (r *Reader) Read() (settings settings.Settings, err error) {
 	settings.VPN, err = readVPN()
 	if err != nil {

internal/configuration/sources/source.go

@@ -5,4 +5,5 @@ import "github.com/qdm12/gluetun/internal/configuration/settings"
 type Source interface {
 	Read() (settings settings.Settings, err error)
 	ReadHealth() (settings settings.Health, err error)
+	String() string
 }