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ssh.go
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ssh.go
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/*
Copyright 2017 WALLIX
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 commands
import (
"fmt"
"io/ioutil"
"net"
"net/http"
"os"
"os/exec"
"path"
"strings"
"sync"
"syscall"
"text/template"
"time"
"golang.org/x/crypto/ssh"
"github.com/spf13/cobra"
"github.com/wallix/awless/aws"
awsconfig "github.com/wallix/awless/aws/config"
"github.com/wallix/awless/cloud"
"github.com/wallix/awless/cloud/properties"
"github.com/wallix/awless/config"
"github.com/wallix/awless/console"
"github.com/wallix/awless/graph"
"github.com/wallix/awless/logger"
)
var keyPathFlag string
var printSSHConfigFlag bool
var printSSHCLIFlag bool
func init() {
RootCmd.AddCommand(sshCmd)
sshCmd.Flags().StringVarP(&keyPathFlag, "identity", "i", "", "Set path toward the identity (key file) to use to connect through SSH")
sshCmd.Flags().BoolVar(&printSSHConfigFlag, "print-config", false, "Print SSH configuration for ~/.ssh/config file.")
sshCmd.Flags().BoolVar(&printSSHCLIFlag, "print-cli", false, "Print the CLI one-liner to connect with SSH. (/usr/bin/ssh user@ip -i ...)")
}
var sshCmd = &cobra.Command{
Use: "ssh [USER@]INSTANCE",
Short: "Launch a SSH (Secure Shell) session to an instance given an id or alias",
Example: ` awless ssh i-8d43b21b # using the instance id
awless ssh ec2-user@redis-prod # using the instance name and specify a user
awless ssh @redis-prod -i ./path/toward/key # with a keyfile`,
PersistentPreRun: applyHooks(initLoggerHook, initAwlessEnvHook, initCloudServicesHook),
PersistentPostRun: applyHooks(saveHistoryHook, verifyNewVersionHook),
RunE: func(cmd *cobra.Command, args []string) error {
if len(args) != 1 {
return fmt.Errorf("instance required")
}
var user, instanceID string
if strings.Contains(args[0], "@") {
user = strings.Split(args[0], "@")[0]
instanceID = strings.Split(args[0], "@")[1]
} else {
instanceID = args[0]
}
resourcesGraph, ip := fetchConnectionInfo()
var inst *graph.Resource
instanceResolvers := []graph.Resolver{&graph.ByProperty{Key: "Name", Value: instanceID}, &graph.ByType{Typ: cloud.Instance}}
resources, err := resourcesGraph.ResolveResources(&graph.And{Resolvers: instanceResolvers})
exitOn(err)
switch len(resources) {
case 0:
// No instance with that name, use the id
inst, err = findResource(resourcesGraph, instanceID, cloud.Instance)
exitOn(err)
case 1:
inst = resources[0]
default:
idStatus := graph.Resources(resources).Map(func(r *graph.Resource) string {
return fmt.Sprintf("%s (%s)", r.Id(), r.Properties[properties.State])
})
logger.Infof("Found %d resources with name '%s': %s", len(resources), instanceID, strings.Join(idStatus, ", "))
var running []*graph.Resource
running, err = resourcesGraph.ResolveResources(&graph.And{Resolvers: append(instanceResolvers, &graph.ByProperty{Key: properties.State, Value: "running"})})
exitOn(err)
switch len(running) {
case 0:
logger.Warning("None of them is running, cannot connect through SSH")
return nil
case 1:
logger.Infof("Found only one instance running: %s. Will connect to this instance.", running[0].Id())
inst = running[0]
default:
logger.Warning("Connect through the running ones using their id:")
for _, res := range running {
var up string
if uptime, ok := res.Properties[properties.Launched].(time.Time); ok {
up = fmt.Sprintf("\t\t(uptime: %s)", console.HumanizeTime(uptime))
}
logger.Warningf("\t`awless ssh %s`%s", res.Id(), up)
}
return nil
}
}
cred, err := instanceCredentialsFromGraph(resourcesGraph, inst, keyPathFlag)
exitOn(err)
var client *ssh.Client
if user != "" {
cred.User = user
client, err = console.NewSSHClient(cred)
if err != nil {
checkInstanceAccessible(resourcesGraph, inst, ip)
exitOn(err)
}
exitOn(sshConnect(instanceID, client, cred))
} else {
for _, user := range awsconfig.DefaultAMIUsers {
logger.Verbosef("trying user '%s'", user)
cred.User = user
client, err = console.NewSSHClient(cred)
if err != nil && strings.Contains(err.Error(), "unable to authenticate") {
continue
}
if err != nil {
checkInstanceAccessible(resourcesGraph, inst, ip)
exitOn(err)
}
exitOn(sshConnect(instanceID, client, cred))
return nil
}
}
exitOn(err)
return nil
},
}
func instanceCredentialsFromGraph(g *graph.Graph, inst *graph.Resource, keyPathFlag string) (*console.Credentials, error) {
ip, ok := inst.Properties[properties.PublicIP]
if !ok {
return nil, fmt.Errorf("no public IP address for instance %s", inst.Id())
}
var keyPath string
if keyPathFlag != "" {
keyPath = keyPathFlag
} else {
keypair, ok := inst.Properties[properties.KeyPair]
if !ok {
return nil, fmt.Errorf("no access key set for instance %s", inst.Id())
}
keyPath = path.Join(config.KeysDir, fmt.Sprint(keypair))
}
return &console.Credentials{IP: fmt.Sprint(ip), User: "", KeyPath: keyPath}, nil
}
func sshConnect(name string, sshClient *ssh.Client, cred *console.Credentials) error {
defer sshClient.Close()
if printSSHConfigFlag {
params := struct {
*console.Credentials
Name string
}{cred, name}
return template.Must(template.New("ssh_config").Parse(`
Host {{ .Name }}
Hostname {{ .IP }}
User {{ .User }}
IdentityFile {{ .KeyPath }}
`)).Execute(os.Stdout, params)
}
sshPath, sshErr := exec.LookPath("ssh")
args := []string{"ssh", "-i", cred.KeyPath, fmt.Sprintf("%s@%s", cred.User, cred.IP)}
if sshErr == nil {
if printSSHCLIFlag {
fmt.Println(sshPath + " " + strings.Join(args[1:], " "))
return nil
}
logger.Infof("Login as '%s' on '%s', using keypair '%s' with ssh client at '%s'", cred.User, cred.IP, cred.KeyPath, sshPath)
return syscall.Exec(sshPath, args, os.Environ())
} else { // Fallback SSH
if printSSHCLIFlag {
fmt.Println(strings.Join(args, " "))
return nil
}
logger.Infof("No SSH. Fallback on builtin client. Login as '%s' on '%s', using keypair '%s'", cred.User, cred.IP, cred.KeyPath)
return console.InteractiveTerminal(sshClient)
}
}
func fetchConnectionInfo() (*graph.Graph, net.IP) {
var resourcesGraph, sgroupsGraph *graph.Graph
var myip net.IP
var wg sync.WaitGroup
var errc = make(chan error)
wg.Add(1)
go func() {
var err error
defer wg.Done()
resourcesGraph, err = aws.InfraService.FetchByType(cloud.Instance)
if err != nil {
errc <- err
}
}()
wg.Add(1)
go func() {
var err error
defer wg.Done()
sgroupsGraph, err = aws.InfraService.FetchByType(cloud.SecurityGroup)
if err != nil {
errc <- err
}
}()
wg.Add(1)
go func() {
defer wg.Done()
client := &http.Client{
Timeout: 2 * time.Second,
}
resp, err := client.Get("http://checkip.amazonaws.com/")
if err == nil {
b, _ := ioutil.ReadAll(resp.Body)
resp.Body.Close()
myip = net.ParseIP(strings.TrimSpace(string(b)))
}
}()
go func() {
wg.Wait()
close(errc)
}()
for err := range errc {
if err != nil {
exitOn(err)
}
}
resourcesGraph.AddGraph(sgroupsGraph)
return resourcesGraph, myip
}
func checkInstanceAccessible(g *graph.Graph, inst *graph.Resource, myip net.IP) {
state, ok := inst.Properties[properties.State]
if st := fmt.Sprint(state); ok && st != "running" {
logger.Warningf("This instance is '%s' (cannot ssh to a non running state)", st)
if st == "stopped" {
logger.Warningf("You can start it with `awless -f start instance id=%s`", inst.Id())
}
return
}
sgroups, ok := inst.Properties[properties.SecurityGroups].([]string)
if ok {
var sshPortOpen, myIPAllowed bool
for _, id := range sgroups {
sgroup, err := findResource(g, id, cloud.SecurityGroup)
if err != nil {
break
}
rules, ok := sgroup.Properties[properties.InboundRules].([]*graph.FirewallRule)
if ok {
for _, r := range rules {
if r.PortRange.Contains(22) {
sshPortOpen = true
}
if myip != nil && r.Contains(myip.String()) {
myIPAllowed = true
}
}
}
}
if !sshPortOpen {
logger.Warning("Port 22 is not open on this instance")
}
if !myIPAllowed && myip != nil {
logger.Warningf("Your ip %s is not authorized for this instance. You might want to update the securitygroup with:", myip)
var group = "mygroup"
if len(sgroups) == 1 {
group = sgroups[0]
}
logger.Warningf("`awless update securitygroup id=%s inbound=authorize protocol=tcp cidr=%s/32 portrange=22`", group, myip)
}
}
}
func findResource(g *graph.Graph, id, typ string) (*graph.Resource, error) {
if found, err := g.FindResource(id); found == nil || err != nil {
return nil, fmt.Errorf("instance '%s' not found", id)
}
return g.GetResource(typ, id)
}