Refactor faasd and faas-containerd merge

The use of containerd and CNI functions has been refactored to reuse
the same codebase.

Added all network functionality to own directory and package. Removed
netlink and weave library in favor of using CNI plugin result files.

Rename containers handler to functions to clear-up functionality.

Signed-off-by: Carlos de Paula <me@carlosedp.com>

pkg/cninetwork/weave.go

@@ -0,0 +1,131 @@
+// Copyright Weaveworks
+// github.com/weaveworks/weave/net
+
+package cninetwork
+
+import (
+	"fmt"
+	"net"
+	"os"
+
+	"github.com/vishvananda/netlink"
+	"github.com/vishvananda/netns"
+)
+
+type Dev struct {
+	Name  string           `json:"Name,omitempty"`
+	MAC   net.HardwareAddr `json:"MAC,omitempty"`
+	CIDRs []*net.IPNet     `json:"CIDRs,omitempty"`
+}
+
+func linkToNetDev(link netlink.Link) (Dev, error) {
+	addrs, err := netlink.AddrList(link, netlink.FAMILY_V4)
+	if err != nil {
+		return Dev{}, err
+	}
+
+	netDev := Dev{Name: link.Attrs().Name, MAC: link.Attrs().HardwareAddr}
+	for _, addr := range addrs {
+		netDev.CIDRs = append(netDev.CIDRs, addr.IPNet)
+	}
+	return netDev, nil
+}
+
+// ConnectedToBridgeVethPeerIds returns peer indexes of veth links connected to
+// the given bridge. The peer index is used to query from a container netns
+// whether the container is connected to the bridge.
+func ConnectedToBridgeVethPeerIds(bridgeName string) ([]int, error) {
+	var ids []int
+
+	br, err := netlink.LinkByName(bridgeName)
+	if err != nil {
+		return nil, err
+	}
+	links, err := netlink.LinkList()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, link := range links {
+		if _, isveth := link.(*netlink.Veth); isveth && link.Attrs().MasterIndex == br.Attrs().Index {
+			peerID := link.Attrs().ParentIndex
+			if peerID == 0 {
+				// perhaps running on an older kernel where ParentIndex doesn't work.
+				// as fall-back, assume the peers are consecutive
+				peerID = link.Attrs().Index - 1
+			}
+			ids = append(ids, peerID)
+		}
+	}
+
+	return ids, nil
+}
+
+// Lookup the weave interface of a container
+func GetWeaveNetDevs(processID int) ([]Dev, error) {
+	peerIDs, err := ConnectedToBridgeVethPeerIds("weave")
+	if err != nil {
+		return nil, err
+	}
+
+	return GetNetDevsByVethPeerIds(processID, peerIDs)
+}
+
+func GetNetDevsByVethPeerIds(processID int, peerIDs []int) ([]Dev, error) {
+	// Bail out if this container is running in the root namespace
+	netnsRoot, err := netns.GetFromPid(1)
+	if err != nil {
+		return nil, fmt.Errorf("unable to open root namespace: %s", err)
+	}
+	defer netnsRoot.Close()
+	netnsContainer, err := netns.GetFromPid(processID)
+	if err != nil {
+		// Unable to find a namespace for this process - just return nothing
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("unable to open process %d namespace: %s", processID, err)
+	}
+	defer netnsContainer.Close()
+	if netnsRoot.Equal(netnsContainer) {
+		return nil, nil
+	}
+
+	// convert list of peerIDs into a map for faster lookup
+	indexes := make(map[int]struct{})
+	for _, id := range peerIDs {
+		indexes[id] = struct{}{}
+	}
+
+	var netdevs []Dev
+	err = WithNetNS(netnsContainer, func() error {
+		links, err := netlink.LinkList()
+		if err != nil {
+			return err
+		}
+
+		for _, link := range links {
+			if _, found := indexes[link.Attrs().Index]; found {
+				netdev, err := linkToNetDev(link)
+				if err != nil {
+					return err
+				}
+				netdevs = append(netdevs, netdev)
+			}
+		}
+		return nil
+	})
+
+	return netdevs, err
+}
+
+// Get the weave bridge interface.
+// NB: Should be called from the root network namespace.
+func GetBridgeNetDev(bridgeName string) (Dev, error) {
+	link, err := netlink.LinkByName(bridgeName)
+	if err != nil {
+		return Dev{}, err
+	}
+
+	return linkToNetDev(link)
+}