113 lines
2.7 KiB
Go
113 lines
2.7 KiB
Go
/*
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Copyright 2020 Roblox Corporation
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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 etchosts
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import (
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"bytes"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"strings"
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"github.com/docker/docker/opts"
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)
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// Code referenced from https://github.com/moby/libnetwork/blob/master/etchosts/etchosts.go
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// Record Structure for a single host record
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type Record struct {
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Hosts string
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IP string
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}
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// WriteTo writes record to file and returns bytes written or error
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func (r Record) WriteTo(w io.Writer) (int64, error) {
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n, err := fmt.Fprintf(w, "%s\t%s\n", r.IP, r.Hosts)
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return int64(n), err
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}
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var (
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// Default hosts config records slice
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defaultContent = []Record{
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{Hosts: "localhost", IP: "127.0.0.1"},
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{Hosts: "localhost ip6-localhost ip6-loopback", IP: "::1"},
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{Hosts: "ip6-localnet", IP: "fe00::0"},
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{Hosts: "ip6-mcastprefix", IP: "ff00::0"},
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{Hosts: "ip6-allnodes", IP: "ff02::1"},
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{Hosts: "ip6-allrouters", IP: "ff02::2"},
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}
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)
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// BuildEtcHosts builds NOMAD_TASK_DIR/etc_hosts with defaults.
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func BuildEtcHosts(hostsFile string) error {
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content := bytes.NewBuffer(nil)
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// Write defaultContent slice to buffer
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for _, r := range defaultContent {
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if _, err := r.WriteTo(content); err != nil {
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return err
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}
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}
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return ioutil.WriteFile(hostsFile, content.Bytes(), 0644)
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}
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// CopyEtcHosts copies /etc/hosts to NOMAD_TASK_DIR/etc_hosts
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func CopyEtcHosts(hostsFile string) error {
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srcFile, err := os.Open("/etc/hosts")
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if err != nil {
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return err
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}
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defer srcFile.Close()
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destFile, err := os.Create(hostsFile)
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if err != nil {
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return err
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}
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defer destFile.Close()
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_, err = io.Copy(destFile, srcFile)
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if err != nil {
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return err
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}
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return nil
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}
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// AddExtraHosts add hosts, given as name:IP to container /etc/hosts.
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func AddExtraHosts(hostsFile string, extraHosts []string) error {
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fd, err := os.OpenFile(hostsFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
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if err != nil {
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return err
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}
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defer fd.Close()
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for _, extraHost := range extraHosts {
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// allow IPv6 addresses in extra hosts; only split on first ":"
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if _, err := opts.ValidateExtraHost(extraHost); err != nil {
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return err
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}
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hostnameIP := strings.SplitN(extraHost, ":", 2)
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msg := fmt.Sprintf("%s\t%s\n", hostnameIP[1], hostnameIP[0])
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if _, err := fd.WriteString(msg); err != nil {
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return err
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}
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}
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return nil
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}
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