refactor: fail to start without listeners

defined as part of the configuration during daemon initialization.

Changelog: other

3 files changed, 26 insertions, 0 deletions

diff --git a/app_test.go b/app_test.go
index 48a6013b..669d041e 100644
--- a/app_test.go
+++ b/app_test.go
@@ -6,6 +6,7 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -84,6 +85,12 @@ func TestHealthCheckMiddleware(t *testing.T) {
 		},
 	}
 
+	// required by LoadConfig
+	require.NoError(t, os.Setenv("LISTEN_HTTP", ":0"))
+	t.Cleanup(func() {
+		require.NoError(t, os.Unsetenv("LISTEN_HTTP"))
+	})
+
 	cfg, err := config.LoadConfig()
 	require.NoError(t, err)
 	cfg.General.StatusPath = "/-/healthcheck"
diff --git a/internal/config/multi_string_flag.go b/internal/config/multi_string_flag.go
index fc63299b..0d90b572 100644
--- a/internal/config/multi_string_flag.go
+++ b/internal/config/multi_string_flag.go
@@ -49,3 +49,7 @@ func (s *MultiStringFlag) sep() string {
 
 	return s.separator
 }
+
+func (s *MultiStringFlag) Len() int {
+	return len(s.value)
+}
diff --git a/internal/config/validate.go b/internal/config/validate.go
index f73aabff..87f932c0 100644
--- a/internal/config/validate.go
+++ b/internal/config/validate.go
@@ -10,6 +10,10 @@ import (
 )
 
 func validateConfig(config *Config) error {
+	if err := validateListeners(config); err != nil {
+		return err
+	}
+
 	if err := validateAuthConfig(config); err != nil {
 		return err
 	}
@@ -21,6 +25,17 @@ func validateConfig(config *Config) error {
 	return tls.ValidateTLSVersions(*tlsMinVersion, *tlsMaxVersion)
 }
 
+func validateListeners(config *Config) error {
+	if config.ListenHTTPStrings.Len() == 0 &&
+		config.ListenHTTPSStrings.Len() == 0 &&
+		config.ListenHTTPSProxyv2Strings.Len() == 0 &&
+		config.ListenProxyStrings.Len() == 0 {
+		return errors.New("no listener defined, please specify at least one --listen-* flag")
+	}
+
+	return nil
+}
+
 func validateAuthConfig(config *Config) error {
 	if config.Authentication.Secret == "" && config.Authentication.ClientID == "" &&
 		config.Authentication.ClientSecret == "" && config.Authentication.RedirectURI == "" {