ITQC/containernetworking-plugins
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Use single IP on the host for ptp veths

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Instead of allocating a /31 for each container,
use the same IP on the host side for all veths.
This is very similar how real point-to-point
devices work (using donor IPs).
This commit is contained in:
Eugene Yakubovich 2015-09-17 11:49:21 -07:00 committed by Stefan Junker
parent 94be1cfaab
commit 7d8d6b2a7e
1 changed files with 62 additions and 2 deletions
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64
plugins/main/ptp/ptp.go
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@ -46,6 +46,17 @@ type NetConf struct {
}
func setupContainerVeth(netns, ifName string, mtu int, pr *types.Result) (string, error) {
// The IPAM result will be something like IP=192.168.3.5/24, GW=192.168.3.1.
// What we want is really a point-to-point link but veth does not support IFF_POINTOPONT.
// Next best thing would be to let it ARP but set interface to 192.168.3.5/32 and
// add a route like "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// Unfortunately that won't work as the GW will be outside the interface's subnet.
// Our solution is to configure the interface with 192.168.3.5/24, then delete the
// "192.168.3.0/24 dev $ifName" route that was automatically added. Then we add
// "192.168.3.1/32 dev $ifName" and "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// In other words we force all traffic to ARP via the gateway except for GW itself.
var hostVethName string
err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) error {
hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
@ -53,11 +64,56 @@ func setupContainerVeth(netns, ifName string, mtu int, pr *types.Result) (string
return err
}
err = ipam.ConfigureIface(ifName, pr)
if err = ipam.ConfigureIface(ifName, pr); err != nil {
return err
}
contVeth, err := netlink.LinkByName(ifName)
if err != nil {
return err
}
// Delete the route that was automatically added
route := netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_LINK,
Src: pr.IP4.IP.IP,
}
if err := netlink.RouteDel(&route); err != nil {
return err
}
for _, r := range []netlink.Route{
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.Gateway,
Mask: net.CIDRMask(32, 32),
},
Scope: netlink.SCOPE_LINK,
Src: pr.IP4.IP.IP,
},
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_UNIVERSE,
Gw: pr.IP4.Gateway,
Src: pr.IP4.IP.IP,
},
} {
if err := netlink.RouteAdd(&r); err != nil {
return err
}
}
hostVethName = hostVeth.Attrs().Name
return nil
@ -75,13 +131,17 @@ func setupHostVeth(vethName string, ipConf *types.IPConfig) error {
// TODO(eyakubovich): IPv6
ipn := &net.IPNet{
IP: ipConf.Gateway,
Mask: net.CIDRMask(31, 32),
Mask: net.CIDRMask(32, 32),
}
addr := &netlink.Addr{IPNet: ipn, Label: ""}
if err = netlink.AddrAdd(veth, addr); err != nil {
return fmt.Errorf("failed to add IP addr (%#v) to veth: %v", ipn, err)
}
ipn = &net.IPNet{
IP: ipConf.IP.IP,
Mask: net.CIDRMask(32, 32),
}
// dst happens to be the same as IP/net of host veth
if err = ip.AddHostRoute(ipn, nil, veth); err != nil && !os.IsExist(err) {
return fmt.Errorf("failed to add route on host: %v", err)