A secret reaches a process as a file (ADR 0086)

The broker settings take a _FILE twin like the store connections; the
catalogue engine refuses a secret placeholder in a container's env and a
secret-carrying env-file unless the container says why with
secrets-in-environment, which stays in the catalogue and never reaches the
machine.

internal/broker/management.go

@@ -5,10 +5,10 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/novox/mesh-controller/internal/envfile"
 	"io"
 	"net/http"
 	"net/url"
-	"os"
 	"regexp"
 	"strings"
 	"time"
@@ -42,7 +42,10 @@ type Management struct {
 
 // ManagementFromEnvironment reads where the management API is, if it is configured.
 func ManagementFromEnvironment() (*Management, error) {
-	raw := strings.TrimSpace(os.Getenv(ManagementVar))
+	raw, err := envfile.Value(ManagementVar)
+	if err != nil {
+		return nil, err
+	}
 	if raw == "" {
 		return nil, ErrNotConfigured
 	}