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/broker.go

@@ -16,6 +16,7 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
+	"github.com/novox/mesh-controller/internal/envfile"
 	"os"
 	"strings"
 )
@@ -40,7 +41,10 @@ var ErrNotConfigured = errors.New("this control plane has not been told about it
 
 // FromEnvironment reads the two settings, if they are there.
 func FromEnvironment() (Broker, error) {
-	address := strings.TrimSpace(os.Getenv(AddressVar))
+	address, err := envfile.Value(AddressVar)
+	if err != nil {
+		return Broker{}, err
+	}
 	path := strings.TrimSpace(os.Getenv(CertificateVar))
 
 	if address == "" && path == "" {