system prune: remove all networks

podman system prune should also remove all networks. When we want to
users to migrate to the new network stack we recommend to run podman
system reset. However this did not remove networks and if there were
still networks around we would continue to use cni since this was
considered an old system.

There is one exception for the default network. It should not be removed
since this could cause other issues when it no longer exists. The
network backend detection logic ignores the default network so this is
fine.

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

cmd/podman/system/reset.go

@@ -21,7 +21,7 @@ import (
 var (
 	systemResetDescription = `Reset podman storage back to default state"
 
-  All containers will be stopped and removed, and all images, volumes and container content will be removed.
+  All containers will be stopped and removed, and all images, volumes, networks and container content will be removed.
 `
 	systemResetCommand = &cobra.Command{
 		Annotations:       map[string]string{registry.EngineMode: registry.ABIMode},
@@ -55,11 +55,11 @@ func reset(cmd *cobra.Command, args []string) {
 	// Prompt for confirmation if --force is not set
 	if !forceFlag {
 		reader := bufio.NewReader(os.Stdin)
-		fmt.Println(`
-WARNING! This will remove:
+		fmt.Println(`WARNING! This will remove:
         - all containers
         - all pods
         - all images
+        - all networks
         - all build cache`)
 		if len(listCtn) > 0 {
 			fmt.Println(`WARNING! The following external containers will be purged:`)

docs/source/markdown/podman-system-reset.1.md

@@ -7,7 +7,7 @@ podman\-system\-reset - Reset storage back to initial state
 **podman system reset** [*options*]
 
 ## DESCRIPTION
-**podman system reset** removes all pods, containers, images and volumes.
+**podman system reset** removes all pods, containers, images, networks and volumes.
 
 This command must be run **before** changing any of the following fields in the
 `containers.conf` or `storage.conf` files: `driver`, `static_dir`, `tmp_dir`
@@ -28,6 +28,17 @@ Print usage statement
 
 ## EXAMPLES
 
+```
+$ podman system reset
+WARNING! This will remove:
+        - all containers
+        - all pods
+        - all images
+        - all networks
+        - all build cache
+Are you sure you want to continue? [y/N] y
+```
+
 ### Switching rootless user from VFS driver to overlay with fuse-overlayfs
 
 If the user ran rootless containers without having the `fuse-overlayfs` program

libpod/reset.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 
 	"github.com/containers/common/libimage"
+	"github.com/containers/common/libnetwork/types"
 	"github.com/containers/podman/v4/libpod/define"
 	"github.com/containers/podman/v4/pkg/errorhandling"
 	"github.com/containers/podman/v4/pkg/rootless"
@@ -70,6 +71,22 @@ func (r *Runtime) Reset(ctx context.Context) error {
 		}
 	}
 
+	// remove all networks
+	nets, err := r.network.NetworkList()
+	if err != nil {
+		return err
+	}
+	for _, net := range nets {
+		// do not delete the default network
+		if net.Name == r.network.DefaultNetworkName() {
+			continue
+		}
+		// ignore not exists errors because of the TOCTOU problem
+		if err := r.network.NetworkRemove(net.Name); err != nil && !errors.Is(err, types.ErrNoSuchNetwork) {
+			logrus.Errorf("Removing network %s: %v", net.Name, err)
+		}
+	}
+
 	xdgRuntimeDir := filepath.Clean(os.Getenv("XDG_RUNTIME_DIR"))
 	_, prevError := r.store.Shutdown(true)
 	graphRoot := filepath.Clean(r.store.GraphRoot())

test/e2e/system_reset_test.go

@@ -38,6 +38,10 @@ var _ = Describe("podman system reset", func() {
 		SkipIfRemote("system reset not supported on podman --remote")
 		// system reset will not remove additional store images, so need to grab length
 
+		// change the network dir so that we do not conflict with other tests
+		// that would use the same network dir and cause unnecessary flakes
+		podmanTest.NetworkConfigDir = tempdir
+
 		session := podmanTest.Podman([]string{"rmi", "--force", "--all"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
@@ -56,16 +60,16 @@ var _ = Describe("podman system reset", func() {
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 
+		session = podmanTest.Podman([]string{"network", "create"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+
 		session = podmanTest.Podman([]string{"system", "reset", "-f"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 
 		Expect(session.ErrorToString()).To(Not(ContainSubstring("Failed to add pause process")))
 
-		// If remote then the API service should have exited
-		// On local tests this is a noop
-		podmanTest.StartRemoteService()
-
 		session = podmanTest.Podman([]string{"images", "-n"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
@@ -80,5 +84,11 @@ var _ = Describe("podman system reset", func() {
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 		Expect(session.OutputToStringArray()).To(BeEmpty())
+
+		session = podmanTest.Podman([]string{"network", "ls", "-q"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		// default network should exists
+		Expect(session.OutputToStringArray()).To(HaveLen(1))
 	})
 })