Azure get-credentials errors running in golang program

I am trying to azure acs kubernetes credentials with the following script:

#! /bin/sh
az login --service-principal --username=user -password=password --tenant=tenant
az acs kubernetes get-credentials --resource-group=rg --name=acs1 --file=/tmp/kubeconfig.json --ssh-key-file=private.key --output=json --debug --verbose

Running the script from command line on the mac works ok. When I try to run a golang program "cmd := exec.Command("/bin/sh", "-c", scriptName)" that calls the same script on the same computer I get the following error:

No existing session
Traceback (most recent call last):
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/main.py", line 36, in main
    cmd_result = APPLICATION.execute(args)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/core/application.py", line 211, in execute
    result = expanded_arg.func(params)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 351, in __call__
    return self.handler(*args, **kwargs)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 555, in _execute_command
    reraise(*sys.exc_info())
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/core/commands/__init__.py", line 532, in _execute_command
    result = op(client, **kwargs) if client else op(**kwargs)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/command_modules/acs/custom.py", line 785, in k8s_get_credentials
    _k8s_get_credentials_internal(name, acs_info, path, ssh_key_file)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/command_modules/acs/custom.py", line 806, in _k8s_get_credentials_internal
    '.kube/config', path_candidate, key_filename=ssh_key_file)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/azure/cli/command_modules/acs/acs_client.py", line 62, in secure_copy
    ssh.connect(host, username=user, pkey=pkey)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/paramiko/client.py", line 394, in connect
    look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host)
  File "/Users/aarontorgerson/lib/azure-cli/lib/python2.7/site-packages/paramiko/client.py", line 649, in _auth
    raise saved_exception
SSHException: No existing session

Any ideas?

According to your description and the error information SSHException: No existing session, it sounds like you were using os/exec for calling your shell script file, but failed because command az needs to use something like azureProfile.json at the path .azure within a ssh session.

So I suggested you can try to use the code below with golang.org/x/crypto/ssh package to do it.

Here is my sample code for Linux which I think the same as on MacOS.

package main
import (
"bufio"
"bytes"
"errors"
"fmt"
"log"
"os"
"path/filepath"
"strings"
"golang.org/x/crypto/ssh"
)
func getHostKey(host string) (ssh.PublicKey, error) {
file, err := os.Open(filepath.Join(os.Getenv("HOME"), ".ssh", "known_hosts"))
if err != nil {
return nil, err
}
defer file.Close()
scanner := bufio.NewScanner(file)
var hostKey ssh.PublicKey
for scanner.Scan() {
fields := strings.Split(scanner.Text(), " ")
if len(fields) != 3 {
continue
}
if strings.Contains(fields[0], host) {
var err error
hostKey, _, _, _, err = ssh.ParseAuthorizedKey(scanner.Bytes())
if err != nil {
return nil, errors.New(fmt.Sprintf("error parsing %q: %v", fields[2], err))
}
break
}
}
if hostKey == nil {
return nil, errors.New(fmt.Sprintf("no hostkey for %s", host))
}
return hostKey, nil
}
func main() {
hostKey, err := getHostKey("localhost")
if err != nil {
log.Fatal(err)
}
config := &ssh.ClientConfig{
User: "peter",
Auth: []ssh.AuthMethod{
ssh.Password("peter ssh password"),
},
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
// Dial your ssh server.
conn, err := ssh.Dial("tcp", "localhost:22", config)
if err != nil {
log.Fatal("unable to connect: ", err)
}
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
log.Fatal("Failed to create session: ", err)
}
defer session.Close()
// Once a Session is created, you can execute a single command on
// the remote side using the Run method.
var b bytes.Buffer
session.Stdout = &b
if err := session.Run("./test.sh"); err != nil {
log.Fatal("Failed to run: " + err.Error())
}
fmt.Println(b.String())
}

Notes: There must be a record like the content below for localhost in your .ssh/known_hosts file. If not, you can first login via ssh to generate it and change the host with localhost.

> |localhost|qx8q1geNHGyRFp8Ttu+m2xY4OpU=|noyfrjpDRvtIzP2gzWEV77VZULo= ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBKXlyt/EFLnqwlNDimn73+wZVgCh3dhXi2YMWN6tHUj5LMirrUt0AtmQQVHex2b2ur79L5P6/L2J28NID569qAA=

Hope it helps.