podman stats: work with network connect/disconnect

Hardcoding the interface name is a bad idea. We have no control over the
actual interface name since the user can change it.

The correct thing is to read them from the network status. Since the
contianer can have more than one interface we have to add the RX/TX
values. The other values are currently not used.

For podman 5.0 we should change it so that the API can return the
statistics per interface and the client should sum the TX/RX for the
command output. This is what docker is doing.

Fixes #13824

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

2 files changed, 37 insertions, 7 deletions

diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index 73e64530e..37fa9b5f5 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -930,6 +930,8 @@ func (r *Runtime) reloadContainerNetwork(ctr *Container) (map[string]types.Statu
 	return r.configureNetNS(ctr, ctr.state.NetNS)
 }
 
+// TODO (5.0): return the statistics per network interface
+// This would allow better compat with docker.
 func getContainerNetIO(ctr *Container) (*netlink.LinkStatistics, error) {
 	var netStats *netlink.LinkStatistics
 
@@ -943,21 +945,39 @@ func getContainerNetIO(ctr *Container) (*netlink.LinkStatistics, error) {
 		return nil, nil
 	}
 
-	// FIXME get the interface from the container netstatus
-	dev := "eth0"
 	netMode := ctr.config.NetMode
+	netStatus := ctr.getNetworkStatus()
 	if otherCtr != nil {
 		netMode = otherCtr.config.NetMode
+		netStatus = otherCtr.getNetworkStatus()
 	}
 	if netMode.IsSlirp4netns() {
-		dev = "tap0"
+		// create a fake status with correct interface name for the logic below
+		netStatus = map[string]types.StatusBlock{
+			"slirp4netns": {
+				Interfaces: map[string]types.NetInterface{"tap0": {}},
+			},
+		}
 	}
 	err := ns.WithNetNSPath(netNSPath, func(_ ns.NetNS) error {
-		link, err := netlink.LinkByName(dev)
-		if err != nil {
-			return err
+		for _, status := range netStatus {
+			for dev := range status.Interfaces {
+				link, err := netlink.LinkByName(dev)
+				if err != nil {
+					return err
+				}
+				if netStats == nil {
+					netStats = link.Attrs().Statistics
+					continue
+				}
+				// Currently only Tx/RxBytes are used.
+				// In the future we should return all stats per interface so that
+				// api users have a better options.
+				stats := link.Attrs().Statistics
+				netStats.TxBytes += stats.TxBytes
+				netStats.RxBytes += stats.RxBytes
+			}
 		}
-		netStats = link.Attrs().Statistics
 		return nil
 	})
 	return netStats, err
diff --git a/test/e2e/network_connect_disconnect_test.go b/test/e2e/network_connect_disconnect_test.go
index a0716c84d..019bb4617 100644
--- a/test/e2e/network_connect_disconnect_test.go
+++ b/test/e2e/network_connect_disconnect_test.go
@@ -114,6 +114,11 @@ var _ = Describe("Podman network connect and disconnect", func() {
 		exec3.WaitWithDefaultTimeout()
 		Expect(exec3).Should(Exit(0))
 		Expect(strings.Contains(exec3.OutputToString(), ns)).To(BeFalse())
+
+		// make sure stats still works https://github.com/containers/podman/issues/13824
+		stats := podmanTest.Podman([]string{"stats", "test", "--no-stream"})
+		stats.WaitWithDefaultTimeout()
+		Expect(stats).Should(Exit(0))
 	})
 
 	It("bad network name in connect should result in error", func() {
@@ -237,6 +242,11 @@ var _ = Describe("Podman network connect and disconnect", func() {
 		Expect(exec3).Should(Exit(0))
 		Expect(strings.Contains(exec3.OutputToString(), ns)).To(BeTrue())
 
+		// make sure stats works https://github.com/containers/podman/issues/13824
+		stats := podmanTest.Podman([]string{"stats", "test", "--no-stream"})
+		stats.WaitWithDefaultTimeout()
+		Expect(stats).Should(Exit(0))
+
 		// make sure no logrus errors are shown https://github.com/containers/podman/issues/9602
 		rm := podmanTest.Podman([]string{"rm", "--time=0", "-f", "test"})
 		rm.WaitWithDefaultTimeout()