k3s/pkg/agent/flannel/flannel.go

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//
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// Copyright 2015 flannel authors
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// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package flannel
import (
"fmt"
"net"
"os"
"path/filepath"
"sync"
"github.com/flannel-io/flannel/backend"
"github.com/flannel-io/flannel/network"
"github.com/flannel-io/flannel/pkg/ip"
"github.com/flannel-io/flannel/subnet/kube"
"github.com/sirupsen/logrus"
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"golang.org/x/net/context"
// Backends need to be imported for their init() to get executed and them to register
_ "github.com/flannel-io/flannel/backend/extension"
_ "github.com/flannel-io/flannel/backend/hostgw"
_ "github.com/flannel-io/flannel/backend/ipsec"
_ "github.com/flannel-io/flannel/backend/vxlan"
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)
const (
subnetFile = "/run/flannel/subnet.env"
)
func flannel(ctx context.Context, flannelIface *net.Interface, flannelConf, kubeConfigFile string, flannelIPv6Masq bool, netMode int) error {
extIface, err := LookupExtInterface(flannelIface, netMode)
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if err != nil {
return err
}
sm, err := kube.NewSubnetManager(ctx, "", kubeConfigFile, "flannel.alpha.coreos.com", flannelConf, false)
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if err != nil {
return err
}
config, err := sm.GetNetworkConfig(ctx)
if err != nil {
return err
}
// Create a backend manager then use it to create the backend and register the network with it.
bm := backend.NewManager(ctx, sm, extIface)
be, err := bm.GetBackend(config.BackendType)
if err != nil {
return err
}
bn, err := be.RegisterNetwork(ctx, &sync.WaitGroup{}, config)
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if err != nil {
return err
}
if netMode == (ipv4+ipv6) || netMode == ipv4 {
go network.SetupAndEnsureIPTables(network.MasqRules(config.Network, bn.Lease()), 60)
go network.SetupAndEnsureIPTables(network.ForwardRules(config.Network.String()), 50)
}
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if flannelIPv6Masq && config.IPv6Network.String() != emptyIPv6Network {
logrus.Debugf("Creating IPv6 masquerading iptables rules for %s network", config.IPv6Network.String())
go network.SetupAndEnsureIP6Tables(network.MasqIP6Rules(config.IPv6Network, bn.Lease()), 60)
go network.SetupAndEnsureIP6Tables(network.ForwardRules(config.IPv6Network.String()), 50)
}
if err := WriteSubnetFile(subnetFile, config.Network, config.IPv6Network, true, bn, netMode); err != nil {
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// Continue, even though it failed.
logrus.Warningf("Failed to write flannel subnet file: %s", err)
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} else {
logrus.Infof("Wrote flannel subnet file to %s", subnetFile)
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}
// Start "Running" the backend network. This will block until the context is done so run in another goroutine.
logrus.Info("Running flannel backend.")
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bn.Run(ctx)
return nil
}
func LookupExtInterface(iface *net.Interface, netMode int) (*backend.ExternalInterface, error) {
var ifaceAddr []net.IP
var ifacev6Addr []net.IP
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var err error
if iface == nil {
logrus.Debug("No interface defined for flannel in the config. Fetching the default gateway interface")
if netMode == ipv4 || netMode == (ipv4+ipv6) {
if iface, err = ip.GetDefaultGatewayInterface(); err != nil {
return nil, fmt.Errorf("failed to get default interface: %s", err)
}
} else {
if iface, err = ip.GetDefaultV6GatewayInterface(); err != nil {
return nil, fmt.Errorf("failed to get default interface: %s", err)
}
}
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}
logrus.Debugf("The interface %s will be used by flannel", iface.Name)
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switch netMode {
case ipv4:
ifaceAddr, err = ip.GetInterfaceIP4Addrs(iface)
if err != nil {
return nil, fmt.Errorf("failed to find IPv4 address for interface %s", iface.Name)
}
logrus.Infof("The interface %s with ipv4 address %s will be used by flannel", iface.Name, ifaceAddr[0])
ifacev6Addr = append(ifacev6Addr, nil)
case ipv6:
ifacev6Addr, err = ip.GetInterfaceIP6Addrs(iface)
if err != nil {
return nil, fmt.Errorf("failed to find IPv6 address for interface %s", iface.Name)
}
logrus.Infof("The interface %s with ipv6 address %s will be used by flannel", iface.Name, ifacev6Addr[0])
ifaceAddr = append(ifaceAddr, nil)
case (ipv4 + ipv6):
ifaceAddr, err = ip.GetInterfaceIP4Addrs(iface)
if err != nil {
return nil, fmt.Errorf("failed to find IPv4 address for interface %s", iface.Name)
}
logrus.Infof("The interface %s with ipv4 address %s will be used by flannel", iface.Name, ifaceAddr[0])
ifacev6Addr, err = ip.GetInterfaceIP6Addrs(iface)
if err != nil {
return nil, fmt.Errorf("failed to find IPv6 address for interface %s", iface.Name)
}
logrus.Infof("Using dual-stack mode. The ipv6 address %s will be used by flannel", ifacev6Addr[0])
default:
ifaceAddr = append(ifaceAddr, nil)
ifacev6Addr = append(ifacev6Addr, nil)
}
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if iface.MTU == 0 {
return nil, fmt.Errorf("failed to determine MTU for %s interface", iface.Name)
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}
return &backend.ExternalInterface{
Iface: iface,
IfaceAddr: ifaceAddr[0],
IfaceV6Addr: ifacev6Addr[0],
ExtAddr: ifaceAddr[0],
ExtV6Addr: ifacev6Addr[0],
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}, nil
}
func WriteSubnetFile(path string, nw ip.IP4Net, nwv6 ip.IP6Net, ipMasq bool, bn backend.Network, netMode int) error {
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dir, name := filepath.Split(path)
os.MkdirAll(dir, 0755)
tempFile := filepath.Join(dir, "."+name)
f, err := os.Create(tempFile)
if err != nil {
return err
}
// Write out the first usable IP by incrementing
// sn.IP by one
sn := bn.Lease().Subnet
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sn.IP++
if netMode == ipv4 || netMode == (ipv4+ipv6) {
fmt.Fprintf(f, "FLANNEL_NETWORK=%s\n", nw)
fmt.Fprintf(f, "FLANNEL_SUBNET=%s\n", sn)
}
if nwv6.String() != emptyIPv6Network {
snv6 := bn.Lease().IPv6Subnet
snv6.IncrementIP()
fmt.Fprintf(f, "FLANNEL_IPV6_NETWORK=%s\n", nwv6)
fmt.Fprintf(f, "FLANNEL_IPV6_SUBNET=%s\n", snv6)
}
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fmt.Fprintf(f, "FLANNEL_MTU=%d\n", bn.MTU())
_, err = fmt.Fprintf(f, "FLANNEL_IPMASQ=%v\n", ipMasq)
f.Close()
if err != nil {
return err
}
// rename(2) the temporary file to the desired location so that it becomes
// atomically visible with the contents
return os.Rename(tempFile, path)
//TODO - is this safe? What if it's not on the same FS?
}