flannel/use-32-prefix-udp-backend.patch

35 lines
1.5 KiB
Diff

From ed425bdd6fefacb0f06b35fa8f4caedf042dc84d Mon Sep 17 00:00:00 2001
From: "Cel A. Skeggs" <cela@mit.edu>
Date: Thu, 1 Feb 2018 17:49:12 -0500
Subject: [PATCH] backend/udp: Use a /32 prefix for the flannel0 interface
This avoids the kernel's creation of broadcast routes, which prevent
communication from the host with the zeroth subnet to containers on any
other hosts.
---
backend/udp/udp_network.go | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/backend/udp/udp_network.go b/backend/udp/udp_network.go
index 1f9752f8..242ebf49 100644
--- a/backend/udp/udp_network.go
+++ b/backend/udp/udp_network.go
@@ -153,9 +153,15 @@ func configureIface(ifname string, ipn ip.IP4Net, mtu int) error {
return fmt.Errorf("failed to lookup interface %v", ifname)
}
- err = netlink.AddrAdd(iface, &netlink.Addr{IPNet: ipn.ToIPNet(), Label: ""})
+ // Ensure that the device has a /32 address so that no broadcast routes are created.
+ // This IP is just used as a source address for host to workload traffic (so
+ // the return path for the traffic has an address on the flannel network to use as the destination)
+ ipnLocal := ipn
+ ipnLocal.PrefixLen = 32
+
+ err = netlink.AddrAdd(iface, &netlink.Addr{IPNet: ipnLocal.ToIPNet(), Label: ""})
if err != nil {
- return fmt.Errorf("failed to add IP address %v to %v: %v", ipn.String(), ifname, err)
+ return fmt.Errorf("failed to add IP address %v to %v: %v", ipnLocal.String(), ifname, err)
}
err = netlink.LinkSetMTU(iface, mtu)