Revert "Values without a backing env var should not be expanded (#368)" (#371)

This reverts commit 911fc5a223.

cmd/backup/config_provider.go

@@ -4,14 +4,13 @@
 package main
 
 import (
-	"context"
 	"fmt"
 	"os"
 	"path/filepath"
 
+	"github.com/joho/godotenv"
 	"github.com/offen/docker-volume-backup/internal/errwrap"
 	"github.com/offen/envconfig"
-	"mvdan.cc/sh/shell"
 )
 
 type configStrategy string
@@ -100,7 +99,11 @@ func loadConfigsFromEnvFiles(directory string) ([]*Config, error) {
 			continue
 		}
 		p := filepath.Join(directory, item.Name())
-		envFile, err := source(p)
+		f, err := os.ReadFile(p)
+		if err != nil {
+			return nil, errwrap.Wrap(err, fmt.Sprintf("error reading %s", item.Name()))
+		}
+		envFile, err := godotenv.Unmarshal(os.ExpandEnv(string(f)))
 		if err != nil {
 			return nil, errwrap.Wrap(err, fmt.Sprintf("error reading config file %s", p))
 		}
@@ -122,17 +125,3 @@ func loadConfigsFromEnvFiles(directory string) ([]*Config, error) {
 
 	return configs, nil
 }
-
-// source tries to mimic the pre v2.37.0 behavior of calling
-// `set +a; source $path; set -a` and returns the env vars as a map
-func source(path string) (map[string]string, error) {
-	vars, err := shell.SourceFile(context.Background(), path)
-	if err != nil {
-		return nil, errwrap.Wrap(err, "error sourcing conf file")
-	}
-	result := map[string]string{}
-	for key, value := range vars {
-		result[key] = value.String()
-	}
-	return result, nil
-}