fix mandatory parameter in login/logout

fix #5146
Insted of using a registry as mandatory parameter, this path allows podman to use the first registry from registries.conf.

Signed-off-by: Qi Wang <qiwan@redhat.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/cmd/podman/logout.go b/cmd/podman/logout.go
index 4a113b1d0..dec6822cf 100644
--- a/cmd/podman/logout.go
+++ b/cmd/podman/logout.go
@@ -8,7 +8,9 @@ import (
 	"github.com/containers/image/v5/pkg/docker/config"
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/cmd/podman/shared"
+	"github.com/containers/libpod/pkg/registries"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
 
@@ -51,10 +53,16 @@ func logoutCmd(c *cliconfig.LogoutValues) error {
 	if len(args) > 1 {
 		return errors.Errorf("too many arguments, logout takes at most 1 argument")
 	}
+	var server string
 	if len(args) == 0 && !c.All {
-		return errors.Errorf("registry must be given")
+		registriesFromFile, err := registries.GetRegistries()
+		if err != nil || len(registriesFromFile) == 0 {
+			return errors.Errorf("no registries found in registries.conf, a registry must be provided")
+		}
+
+		server = registriesFromFile[0]
+		logrus.Debugf("registry not specified, default to the first registry %q from registries.conf", server)
 	}
-	var server string
 	if len(args) == 1 {
 		server = scrubServer(args[0])
 	}