Return failure when `runsc events` queries a stopped container

This was causing gvisor-containerd-shim to crash because the command
suceeded, but there was no stat present.

PiperOrigin-RevId: 340964921

2 files changed, 13 insertions, 0 deletions

diff --git a/pkg/shim/runsc/BUILD b/pkg/shim/runsc/BUILD
index f08599ebd..cb0001852 100644
--- a/pkg/shim/runsc/BUILD
+++ b/pkg/shim/runsc/BUILD
@@ -10,6 +10,7 @@ go_library(
     ],
     visibility = ["//:sandbox"],
     deps = [
+        "@com_github_containerd_containerd//log:go_default_library",
         "@com_github_containerd_go_runc//:go_default_library",
         "@com_github_opencontainers_runtime_spec//specs-go:go_default_library",
     ],
diff --git a/pkg/shim/runsc/runsc.go b/pkg/shim/runsc/runsc.go
index c5cf68efa..e7c9640ba 100644
--- a/pkg/shim/runsc/runsc.go
+++ b/pkg/shim/runsc/runsc.go
@@ -28,10 +28,12 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/containerd/containerd/log"
 	runc "github.com/containerd/go-runc"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
+// Monitor is the default process monitor to be used by runsc.
 var Monitor runc.ProcessMonitor = runc.Monitor
 
 // DefaultCommand is the default command for Runsc.
@@ -74,6 +76,7 @@ func (r *Runsc) State(context context.Context, id string) (*runc.Container, erro
 	return &c, nil
 }
 
+// CreateOpts is a set of options to Runsc.Create().
 type CreateOpts struct {
 	runc.IO
 	ConsoleSocket runc.ConsoleSocket
@@ -197,6 +200,7 @@ func (r *Runsc) Wait(context context.Context, id string) (int, error) {
 	return res.ExitStatus, nil
 }
 
+// ExecOpts is a set of options to runsc.Exec().
 type ExecOpts struct {
 	runc.IO
 	PidFile         string
@@ -301,6 +305,7 @@ func (r *Runsc) Run(context context.Context, id, bundle string, opts *CreateOpts
 	return Monitor.Wait(cmd, ec)
 }
 
+// DeleteOpts is a set of options to runsc.Delete().
 type DeleteOpts struct {
 	Force bool
 }
@@ -367,6 +372,13 @@ func (r *Runsc) Stats(context context.Context, id string) (*runc.Stats, error) {
 	if err := json.NewDecoder(rd).Decode(&e); err != nil {
 		return nil, err
 	}
+	log.L.Debugf("Stats returned: %+v", e.Stats)
+	if e.Type != "stats" {
+		return nil, fmt.Errorf(`unexpected event type %q, wanted "stats"`, e.Type)
+	}
+	if e.Stats == nil {
+		return nil, fmt.Errorf(`"runsc events -stat" succeeded but no stat was provided`)
+	}
 	return e.Stats, nil
 }