Create a plugin for up'ing a lo device

- Believe we need sudo to create netns
- Use syscall instead of relying on ip netns
- Add sudo to .travis.yml
- Needs more -E
- Revert Godeps GoVersion to 1.4.2
- in travis, test command is run with all necessary env vars
- Loopback plugin only works on 'lo' interface
- Update README, add loopback plugin config
- note script dependency on jq

Signed-off-by: Gabe Rosenhouse <grosenhouse@pivotal.io>

.travis.yml

@@ -1,4 +1,5 @@
 language: go
+sudo: required
 
 go:
   - 1.4
@@ -12,4 +13,7 @@ install:
  - go get ${TOOLS_CMD}/vet
 
 script:
- - ./test
+ - sudo -E /bin/bash -c 'PATH=$GOROOT/bin:$PATH ./test'
+
+notifications:
+  email: false

Godeps/Godeps.json

@@ -1,6 +1,6 @@
 {
 	"ImportPath": "github.com/appc/cni",
-	"GoVersion": "go1.5.3",
+	"GoVersion": "go1.4.2",
 	"Packages": [
 		"./..."
 	],

README.md

@@ -24,7 +24,9 @@ This repository includes a number of common plugins that can be found in plugins
 Please see Documentation/ folder for documentation about particular plugins.
 
 ## Running the plugins
-The scripts/ directory contains two scripts, priv-net-run.sh and docker-run.sh, that can be used to exercise the plugins.
+The scripts/ directory contains two scripts, `priv-net-run.sh` and `docker-run.sh`, that can be used to exercise the plugins.
+
+**note - priv-net-run.sh depends on `jq`**
 
 Start out by creating a netconf file to describe a network:
 
@@ -46,6 +48,11 @@ $ cat >/etc/cni/net.d/10-mynet.conf <<EOF
 	}
 }
 EOF
+$ cat >/etc/cni/net.d/99-loopback.conf <<EOF
+{
+	"type": "loopback"
+}
+EOF
 ```
 
 The directory `/etc/cni/net.d` is the default location in which the scripts will look for net configurations.

plugins/main/loopback/loopback.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"os"
+
+	"github.com/appc/cni/pkg/ns"
+	"github.com/appc/cni/pkg/skel"
+	"github.com/vishvananda/netlink"
+)
+
+func cmdAdd(args *skel.CmdArgs) error {
+	args.IfName = "lo" // ignore config, this only works for loopback
+	err := ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
+		link, err := netlink.LinkByName(args.IfName)
+		if err != nil {
+			return err // not tested
+		}
+
+		err = netlink.LinkSetUp(link)
+		if err != nil {
+			return err // not tested
+		}
+
+		return nil
+	})
+	if err != nil {
+		return err // not tested
+	}
+
+	return nil
+}
+
+func cmdDel(args *skel.CmdArgs) error {
+	// del does nothing, we're going to destroy the device anyway
+	return nil
+}
+
+func main() {
+	skel.PluginMain(cmdAdd, cmdDel)
+}

plugins/main/loopback/loopback_suite_test.go

@@ -0,0 +1,58 @@
+package main_test
+
+import (
+	"os"
+
+	"github.com/onsi/gomega/gexec"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+
+	"golang.org/x/sys/unix"
+)
+
+var pathToLoPlugin string
+
+func TestLoopback(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Loopback Suite")
+}
+
+var _ = BeforeSuite(func() {
+	var err error
+	pathToLoPlugin, err = gexec.Build("github.com/appc/cni/plugins/main/loopback")
+	Expect(err).NotTo(HaveOccurred())
+})
+
+var _ = AfterSuite(func() {
+	gexec.CleanupBuildArtifacts()
+})
+
+func makeNetworkNS(containerID string) string {
+	namespace := "/var/run/netns/" + containerID
+
+	err := os.MkdirAll("/var/run/netns", 0600)
+	Expect(err).NotTo(HaveOccurred())
+
+	err = unix.Unshare(unix.CLONE_NEWNET)
+	Expect(err).NotTo(HaveOccurred())
+
+	fd, err := os.Create(namespace)
+	Expect(err).NotTo(HaveOccurred())
+	defer fd.Close()
+
+	err = unix.Mount("/proc/self/ns/net", namespace, "none", unix.MS_BIND, "")
+	Expect(err).NotTo(HaveOccurred())
+
+	Expect(namespace).To(BeAnExistingFile())
+	return namespace
+}
+
+func removeNetworkNS(networkNS string) error {
+	err := unix.Unmount(networkNS, unix.MNT_DETACH)
+
+	err = os.RemoveAll(networkNS)
+	return err
+}

plugins/main/loopback/loopback_test.go

@@ -0,0 +1,70 @@
+package main_test
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/appc/cni/pkg/ns"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"github.com/onsi/gomega/gexec"
+)
+
+var _ = Describe("Loopback", func() {
+	var (
+		networkNS   string
+		containerID string
+		command     *exec.Cmd
+	)
+
+	BeforeEach(func() {
+		command = exec.Command(pathToLoPlugin)
+
+		environ := os.Environ()
+
+		containerID = "some-container-id"
+		networkNS = makeNetworkNS(containerID)
+
+		cniEnvVars := []string{
+			fmt.Sprintf("CNI_COMMAND=%s", "ADD"),
+			fmt.Sprintf("CNI_CONTAINERID=%s", containerID),
+			fmt.Sprintf("CNI_NETNS=%s", networkNS),
+			fmt.Sprintf("CNI_IFNAME=%s", "this is ignored"),
+			fmt.Sprintf("CNI_ARGS=%s", "none"),
+			fmt.Sprintf("CNI_PATH=%s", "/some/test/path"),
+		}
+
+		for _, v := range cniEnvVars {
+			environ = append(environ, v)
+		}
+
+		command.Env = environ
+		command.Stdin = strings.NewReader("this doesn't matter")
+	})
+
+	AfterEach(func() {
+		Expect(removeNetworkNS(networkNS)).To(Succeed())
+	})
+
+	Context("when given a network namespace", func() {
+		It("sets the lo device to UP", func() {
+			session, err := gexec.Start(command, GinkgoWriter, GinkgoWriter)
+			Expect(err).NotTo(HaveOccurred())
+
+			Eventually(session).Should(gexec.Exit(0))
+
+			var lo *net.Interface
+			err = ns.WithNetNSPath(networkNS, false, func(hostNS *os.File) error {
+				var err error
+				lo, err = net.InterfaceByName("lo")
+				return err
+			})
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(lo.Flags & net.FlagUp).To(Equal(net.FlagUp))
+		})
+	})
+})

scripts/priv-net-run.sh

@@ -8,7 +8,6 @@ contid=$(printf '%x%x%x%x' $RANDOM $RANDOM $RANDOM $RANDOM)
 netnspath=/var/run/netns/$contid
 
 ip netns add $contid
-ip netns exec $contid ip link set lo up
 ./exec-plugins.sh add $contid $netnspath