Initial merge of faas-containerd

This patch completes part of the work in #20 by porting the code
for faas-containerd in-tree. When tested, I was able to deploy
and then remove figlet from the store on `x86_64`.

In a follow-up PR, duplication will be removed where possible
and consolidated with updated documentation.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

pkg/provider/handlers/cni_network.go

@@ -0,0 +1,212 @@
+package handlers
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"path"
+	"path/filepath"
+
+	"github.com/containerd/containerd"
+	gocni "github.com/containerd/go-cni"
+	"github.com/pkg/errors"
+)
+
+const (
+	// CNIBinDir describes the directory where the CNI binaries are stored
+	CNIBinDir = "/opt/cni/bin"
+	// CNIConfDir describes the directory where the CNI plugin's configuration is stored
+	CNIConfDir = "/etc/cni/net.d"
+	// NetNSPathFmt gives the path to the a process network namespace, given the pid
+	NetNSPathFmt = "/proc/%d/ns/net"
+
+	// defaultCNIConfFilename is the vanity filename of default CNI configuration file
+	defaultCNIConfFilename = "10-openfaas.conflist"
+	// defaultNetworkName names the "docker-bridge"-like CNI plugin-chain installed when no other CNI configuration is present.
+	// This value appears in iptables comments created by CNI.
+	defaultNetworkName = "openfaas-cni-bridge"
+	// defaultBridgeName is the default bridge device name used in the defaultCNIConf
+	defaultBridgeName = "openfaas0"
+	// defaultSubnet is the default subnet used in the defaultCNIConf -- this value is set to not collide with common container networking subnets:
+	defaultSubnet = "10.62.0.0/16"
+)
+
+// defaultCNIConf is a CNI configuration that enables network access to containers (docker-bridge style)
+var defaultCNIConf = fmt.Sprintf(`
+{
+    "cniVersion": "0.4.0",
+    "name": "%s",
+    "plugins": [
+      {
+        "type": "bridge",
+        "bridge": "%s",
+        "isGateway": true,
+        "ipMasq": true,
+        "ipam": {
+            "type": "host-local",
+            "subnet": "%s",
+            "routes": [
+                { "dst": "0.0.0.0/0" }
+            ]
+        }
+      },
+      {
+        "type": "firewall"
+      }
+    ]
+}
+`, defaultNetworkName, defaultBridgeName, defaultSubnet)
+
+// InitNetwork writes configlist file and initializes CNI network
+func InitNetwork() (gocni.CNI, error) {
+
+	log.Printf("Writing network config...\n")
+	if !dirExists(CNIConfDir) {
+		if err := os.MkdirAll(CNIConfDir, 0755); err != nil {
+			return nil, fmt.Errorf("cannot create directory: %s", CNIConfDir)
+		}
+	}
+
+	netConfig := path.Join(CNIConfDir, defaultCNIConfFilename)
+	if err := ioutil.WriteFile(netConfig, []byte(defaultCNIConf), 644); err != nil {
+		return nil, fmt.Errorf("cannot write network config: %s", defaultCNIConfFilename)
+
+	}
+	// Initialize CNI library
+	cni, err := gocni.New(gocni.WithPluginConfDir(CNIConfDir),
+		gocni.WithPluginDir([]string{CNIBinDir}))
+
+	if err != nil {
+		return nil, fmt.Errorf("error initializing cni: %s", err)
+	}
+
+	// Load the cni configuration
+	if err := cni.Load(gocni.WithLoNetwork, gocni.WithConfListFile(filepath.Join(CNIConfDir, defaultCNIConfFilename))); err != nil {
+		return nil, fmt.Errorf("failed to load cni configuration: %v", err)
+	}
+
+	return cni, nil
+}
+
+// CreateCNINetwork creates a CNI network interface and attaches it to the context
+func CreateCNINetwork(ctx context.Context, cni gocni.CNI, task containerd.Task, labels map[string]string) (*gocni.CNIResult, error) {
+	id := NetID(task)
+	netns := NetNamespace(task)
+	result, err := cni.Setup(ctx, id, netns, gocni.WithLabels(labels))
+	if err != nil {
+		return nil, errors.Wrapf(err, "Failed to setup network for task %q: %v", id, err)
+	}
+
+	return result, nil
+}
+
+// DeleteCNINetwork deletes a CNI network based on task ID and Pid
+func DeleteCNINetwork(ctx context.Context, cni gocni.CNI, client *containerd.Client, name string) error {
+	container, containerErr := client.LoadContainer(ctx, name)
+	if containerErr == nil {
+		task, err := container.Task(ctx, nil)
+		if err != nil {
+			log.Printf("[Delete] unable to find task for container: %s\n", name)
+			return nil
+		}
+
+		log.Printf("[Delete] removing CNI network for: %s\n", task.ID())
+
+		id := NetID(task)
+		netns := NetNamespace(task)
+
+		if err := cni.Remove(ctx, id, netns); err != nil {
+			return errors.Wrapf(err, "Failed to remove network for task: %q, %v", id, err)
+		}
+		log.Printf("[Delete] removed: %s from namespace: %s, ID: %s\n", name, netns, id)
+
+		return nil
+	}
+
+	return errors.Wrapf(containerErr, "Unable to find container: %s, error: %s", name, containerErr)
+}
+
+// GetIPAddress returns the IP address of the created container
+func GetIPAddress(result *gocni.CNIResult, task containerd.Task) (net.IP, error) {
+	// Get the IP of the created interface
+	var ip net.IP
+	for ifName, config := range result.Interfaces {
+		if config.Sandbox == NetNamespace(task) {
+			for _, ipConfig := range config.IPConfigs {
+				if ifName != "lo" && ipConfig.IP.To4() != nil {
+					ip = ipConfig.IP
+				}
+			}
+		}
+	}
+	if ip == nil {
+		return nil, fmt.Errorf("unable to get IP address for: %s", task.ID())
+	}
+	return ip, nil
+}
+
+func GetIPfromPID(pid int) (*net.IP, error) {
+	// https://github.com/weaveworks/weave/blob/master/net/netdev.go
+
+	peerIDs, err := ConnectedToBridgeVethPeerIds(defaultBridgeName)
+	if err != nil {
+		return nil, fmt.Errorf("unable to find peers on: %s %s", defaultBridgeName, err)
+	}
+
+	addrs, addrsErr := GetNetDevsByVethPeerIds(pid, peerIDs)
+	if addrsErr != nil {
+		return nil, fmt.Errorf("unable to find address for veth pair using: %v %s", peerIDs, addrsErr)
+	}
+	return &addrs[0].CIDRs[0].IP, nil
+
+}
+
+// NetID generates the network IF based on task name and task PID
+func NetID(task containerd.Task) string {
+	return fmt.Sprintf("%s-%d", task.ID(), task.Pid())
+}
+
+// NetNamespace generates the namespace path based on task PID.
+func NetNamespace(task containerd.Task) string {
+	return fmt.Sprintf(NetNSPathFmt, task.Pid())
+}
+
+func dirEmpty(dirname string) (isEmpty bool) {
+	if !dirExists(dirname) {
+		return
+	}
+
+	f, err := os.Open(dirname)
+	if err != nil {
+		return
+	}
+	defer func() { _ = f.Close() }()
+
+	// If the first file is EOF, the directory is empty
+	if _, err = f.Readdir(1); err == io.EOF {
+		isEmpty = true
+	}
+	return isEmpty
+}
+
+func dirExists(dirname string) bool {
+	exists, info := pathExists(dirname)
+	if !exists {
+		return false
+	}
+
+	return info.IsDir()
+}
+
+func pathExists(path string) (bool, os.FileInfo) {
+	info, err := os.Stat(path)
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+
+	return true, info
+}