80 lines
2.8 KiB
Go
80 lines
2.8 KiB
Go
/*
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Copyright 2019 The Kubernetes Authors All rights reserved.
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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 oci
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import (
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"fmt"
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"net"
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"os/exec"
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"runtime"
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"strings"
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"github.com/golang/glog"
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"github.com/pkg/errors"
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)
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// RoutableHostIPFromInside returns the ip/dns of the host that container lives on
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// is routable from inside the container
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func RoutableHostIPFromInside(ociBin string, containerName string) (net.IP, error) {
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if ociBin != Docker {
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return nil, fmt.Errorf("RoutableHostIPFromInside is currently only implemented for docker https://github.com/containers/libpod/issues/5205")
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}
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if runtime.GOOS == "linux" {
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return dockerGatewayIP()
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}
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// for windows and mac, the gateway ip is not routable so we use dns trick.
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return digDNS(ociBin, containerName, "host.docker.internal")
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}
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// digDNS will get the IP record for a dns
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func digDNS(ociBin, containerName, dns string) (net.IP, error) {
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if err := PointToHostDockerDaemon(); err != nil {
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return nil, errors.Wrap(err, "point host docker daemon")
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}
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cmd := exec.Command(ociBin, "exec", "-t", containerName, "dig", "+short", dns)
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out, err := cmd.CombinedOutput()
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ip := net.ParseIP(strings.TrimSpace(string(out)))
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if err != nil {
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return ip, errors.Wrapf(err, "resolve dns to ip: %s", string(out))
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}
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glog.Infof("got host ip for mount in container by digging dns: %s", ip.String())
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return ip, nil
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}
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// dockerGatewayIP gets the default gateway ip for the docker bridge on the user's host machine
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// gets the ip from user's host docker
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func dockerGatewayIP() (net.IP, error) {
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if err := PointToHostDockerDaemon(); err != nil {
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return nil, errors.Wrap(err, "point host docker daemon")
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}
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cmd := exec.Command(Docker, "network", "ls", "--filter", "name=bridge", "--format", "{{.ID}}")
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out, err := cmd.CombinedOutput()
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if err != nil {
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return nil, errors.Wrapf(err, "get network bridge. output: %s", string(out))
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}
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bridgeID := strings.TrimSpace(string(out))
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cmd = exec.Command(Docker, "inspect",
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"--format", "{{(index .IPAM.Config 0).Gateway}}", bridgeID)
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out, err = cmd.CombinedOutput()
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if err != nil {
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return nil, errors.Wrapf(err, "inspect IP gatway for bridge network: %q. output: %s", string(out), bridgeID)
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}
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ip := net.ParseIP(strings.TrimSpace(string(out)))
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glog.Infof("got host ip for mount in container by inspect docker network: %s", ip.String())
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return ip, nil
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}
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