add podman volume reload to sync volume plugins

Libpod requires that all volumes are stored in the libpod db. Because
volume plugins can be created outside of podman, it will not show all
available plugins. This podman volume reload command allows users to
sync the libpod db with their external volume plugins. All new volumes
from the plugin are also created in the libpod db and when a volume from
the db no longer exists it will be removed if possible.

There are some problems:
- naming conflicts, in this case we only use the first volume we found.
  This is not deterministic.
- race conditions, we have no control over the volume plugins. It is
  possible that the volumes changed while we run this command.

Fixes #14207

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/cmd/podman/volumes/reload.go b/cmd/podman/volumes/reload.go
new file mode 100644
index 000000000..d0d76fb88
--- /dev/null
+++ b/cmd/podman/volumes/reload.go
@@ -0,0 +1,52 @@
+package volumes
+
+import (
+	"fmt"
+
+	"github.com/containers/common/pkg/completion"
+	"github.com/containers/podman/v4/cmd/podman/registry"
+	"github.com/containers/podman/v4/cmd/podman/utils"
+	"github.com/containers/podman/v4/cmd/podman/validate"
+	"github.com/spf13/cobra"
+)
+
+var (
+	reloadDescription = `Check all configured volume plugins and update the libpod database with all available volumes.
+
+  Existing volumes are also removed from the database when they are no longer present in the plugin.`
+	reloadCommand = &cobra.Command{
+		Use:               "reload",
+		Args:              validate.NoArgs,
+		Short:             "reload all volumes from volume plugins",
+		Long:              reloadDescription,
+		RunE:              reload,
+		ValidArgsFunction: completion.AutocompleteNone,
+	}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Command: reloadCommand,
+		Parent:  volumeCmd,
+	})
+}
+
+func reload(cmd *cobra.Command, args []string) error {
+	report, err := registry.ContainerEngine().VolumeReload(registry.Context())
+	if err != nil {
+		return err
+	}
+	printReload("Added", report.Added)
+	printReload("Removed", report.Removed)
+	errs := (utils.OutputErrors)(report.Errors)
+	return errs.PrintErrors()
+}
+
+func printReload(typ string, values []string) {
+	if len(values) > 0 {
+		fmt.Println(typ + ":")
+		for _, name := range values {
+			fmt.Println(name)
+		}
+	}
+}