Authz: Only have two modes for authz client (#100803)

* Only have "inproc" and "clod" mode

pkg/services/authz/rbac_settings.go

@@ -0,0 +1,59 @@
+package authz
+
+import (
+	"fmt"
+
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+type clientMode string
+
+func (s clientMode) IsValid() bool {
+	switch s {
+	case clientModeInproc, clientModeCloud:
+		return true
+	}
+	return false
+}
+
+const (
+	clientModeCloud  clientMode = "cloud"
+	clientModeInproc clientMode = "inproc"
+)
+
+type authzClientSettings struct {
+	remoteAddress string
+	mode          clientMode
+
+	token            string
+	tokenExchangeURL string
+	tokenNamespace   string
+}
+
+func readAuthzClientSettings(cfg *setting.Cfg) (*authzClientSettings, error) {
+	authzSection := cfg.SectionWithEnvOverrides("authorization")
+	grpcClientAuthSection := cfg.SectionWithEnvOverrides("grpc_client_authentication")
+
+	mode := clientMode(authzSection.Key("mode").MustString(string(clientModeInproc)))
+	if !mode.IsValid() {
+		return nil, fmt.Errorf("authorization: invalid mode %q", mode)
+	}
+
+	s := &authzClientSettings{}
+	s.mode = mode
+	if s.mode == clientModeInproc {
+		return s, nil
+	}
+
+	s.remoteAddress = authzSection.Key("remote_address").MustString("")
+	s.token = grpcClientAuthSection.Key("token").MustString("")
+	s.tokenNamespace = grpcClientAuthSection.Key("token_namespace").MustString("stacks-" + cfg.StackID)
+	s.tokenExchangeURL = grpcClientAuthSection.Key("token_exchange_url").MustString("")
+
+	// When running in cloud mode, the token and tokenExchangeURL are required.
+	if s.token == "" || s.tokenExchangeURL == "" {
+		return nil, fmt.Errorf("authorization:  missing token or tokenExchangeUrl")
+	}
+
+	return s, nil
+}