5447db3048
This changes the userspace proxy so that it cleans up its conntrack settings when a service is removed (as the iptables proxy already does). This could theoretically cause problems when a UDP service as deleted and recreated quickly (with the same IP address). As long as packets from the same UDP source IP and port were going to the same destination IP and port, the the conntrack would apply and the packets would be sent to the old destination. This is astronomically unlikely if you did not specify the IP address to use in the service, and even then, only happens with an "established" UDP connection. However, in cases where a service could be "switched" between using the iptables proxy and the userspace proxy, this case becomes much more frequent.
59 lines
2.1 KiB
Go
59 lines
2.1 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package util
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import (
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"fmt"
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"strings"
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"k8s.io/kubernetes/pkg/util/exec"
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"github.com/golang/glog"
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)
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// Utilities for dealing with conntrack
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const noConnectionToDelete = "0 flow entries have been deleted"
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// DeleteServiceConnection uses the conntrack tool to delete the conntrack entries
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// for the UDP connections specified by the given service IPs
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func DeleteServiceConnections(execer exec.Interface, svcIPs []string) {
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for _, ip := range svcIPs {
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glog.V(2).Infof("Deleting connection tracking state for service IP %s", ip)
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err := ExecConntrackTool(execer, "-D", "--orig-dst", ip, "-p", "udp")
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if err != nil && !strings.Contains(err.Error(), noConnectionToDelete) {
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// TODO: Better handling for deletion failure. When failure occur, stale udp connection may not get flushed.
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// These stale udp connection will keep black hole traffic. Making this a best effort operation for now, since it
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// is expensive to baby-sit all udp connections to kubernetes services.
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glog.Errorf("conntrack returned error: %v", err)
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}
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}
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}
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// ExecConntrackTool executes the conntrack tool using the given parameters
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func ExecConntrackTool(execer exec.Interface, parameters ...string) error {
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conntrackPath, err := execer.LookPath("conntrack")
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if err != nil {
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return fmt.Errorf("error looking for path of conntrack: %v", err)
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}
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output, err := execer.Command(conntrackPath, parameters...).CombinedOutput()
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if err != nil {
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return fmt.Errorf("conntrack command returned: %q, error message: %s", string(output), err)
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}
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return nil
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}
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