Zanzana: Setup GRPC authentication in client/server mode (#98680)

* Zanzana: Setup GRPC authentication in client/server mode

* don't use grpcutils

* refactor

Co-authored-by: Karl Persson <kalle.persson@grafana.com>

* Add a namespace stub for in-proc mode

Co-authored-by: Karl Persson <kalle.persson@grafana.com>

* Read parameters from config

* authorize server requests

* add namespace to the tests context

* use stack id from config

* simplify authorize func

* properly format namespace

* return Unauthenticated if namespace is empty

* use insecure cred only in dev env

* check request namespace

* Use CallCredentials API for client auth

* provide config

* fail if stack id is missing

* improve error message

* use insecure connection by default

---------

Co-authored-by: Karl Persson <kalle.persson@grafana.com>

pkg/setting/settings_zanzana.go

@@ -37,6 +37,13 @@ type ZanzanaSettings struct {
 	// Use streamed version of list objects.
 	// Returns full list of objects, but takes more time.
 	UseStreamedListObjects bool
+
+	// Token used to perform the exchange request.
+	Token string
+	// URL called to perform exchange request.
+	TokenExchangeURL string
+	// URL for signing keys
+	SigningKeysURL string
 }
 
 func (cfg *Cfg) readZanzanaSettings() {
@@ -63,5 +70,9 @@ func (cfg *Cfg) readZanzanaSettings() {
 	s.ListObjectsMaxResults = uint32(sec.Key("list_objects_max_results").MustUint(1000))
 	s.UseStreamedListObjects = sec.Key("use_streamed_list_objects").MustBool(false)
 
+	s.Token = sec.Key("token").MustString("")
+	s.TokenExchangeURL = sec.Key("token_exchange_url").MustString("")
+	s.SigningKeysURL = sec.Key("signing_keys_url").MustString("")
+
 	cfg.Zanzana = s
 }