ContainerApp connection creation fails for PostgreSQL when default output is not json

[dbroeglin]

Describe the bug

If the default output type for AZCLI is not JSON (defined in az cli config file), creating Container App connections for PostgreSQL flexible server fails.

Related command

az containerapp connection create postgres-flexible \
            --connection postgresql  \
            --name ca-pi-test-006 \
            --resource-group rg-pi-test-006 \
            --target-resource-group rg-pi-test-006 \
            --server pg-pi-test-006 \
            --database pi_development \
            --client-type ruby \
            --system-identity \
            --container ca-pi-test-006\
            --customized-keys AZURE_POSTGRESQL_CONNECTIONSTRING=DATABASE_URL

Errors

Unexpected error:

The installed extension 'serviceconnector-passwordless' is in preview.
The command failed with an unexpected error. Here is the traceback:
'bytes' object has no attribute 'get'
Traceback (most recent call last):
  File "/usr/lib64/az/lib/python3.9/site-packages/knack/cli.py", line 233, in invoke
    cmd_result = self.invocation.execute(args)
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/core/commands/__init__.py", line 663, in execute
    raise ex
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/core/commands/__init__.py", line 726, in _run_jobs_serially
    results.append(self._run_job(expanded_arg, cmd_copy))
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/core/commands/__init__.py", line 697, in _run_job
    result = cmd_copy(params)
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/core/commands/__init__.py", line 333, in __call__
    return self.handler(*args, **kwargs)
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/core/commands/command_operation.py", line 121, in handler
    return op(**command_args)
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/command_modules/serviceconnector/custom.py", line 317, in connection_create
    return azext_custom.connection_create_ext(cmd, client, connection_name, client_type,
  File "/home/dominique/.azure/cliextensions/serviceconnector-passwordless/azext_serviceconnector_passwordless/custom.py", line 31, in connection_create_ext
    return connection_create_func(cmd, client, connection_name, client_type,
  File "/usr/lib64/az/lib/python3.9/site-packages/azure/cli/command_modules/serviceconnector/custom.py", line 462, in connection_create_func
    new_auth_info = enable_mi_for_db_linker(
  File "/home/dominique/.azure/cliextensions/serviceconnector-passwordless/azext_serviceconnector_passwordless/_credential_free.py", line 62, in enable_mi_for_db_linker
    target_handler = getTargetHandler(
  File "/home/dominique/.azure/cliextensions/serviceconnector-passwordless/azext_serviceconnector_passwordless/_credential_free.py", line 157, in getTargetHandler
    return PostgresFlexHandler(cmd, target_id, target_type, auth_info, connection_name, skip_prompt)
  File "/home/dominique/.azure/cliextensions/serviceconnector-passwordless/azext_serviceconnector_passwordless/_credential_free.py", line 632, in __init__
    super().__init__(cmd, target_id, target_type,
  File "/home/dominique/.azure/cliextensions/serviceconnector-passwordless/azext_serviceconnector_passwordless/_credential_free.py", line 176, in __init__
    self.login_username = run_cli_cmd(
AttributeError: 'bytes' object has no attribute 'get'

Issue script & Debug output

Not necessary as the stack is clear about the issue.

Expected behavior

It should work even if the user set a different output type in his config.
It works when removing the configuration from ~/.azure/config

Environment Summary

Tested in Cloud Shell:

azure-cli                         2.55.0

core                              2.55.0
telemetry                          1.1.0

Extensions:
ai-examples                        0.2.5
ml                                2.22.0
serviceconnector-passwordless              0.3.13
ssh                                2.0.2

Dependencies:
msal                            1.24.0b2
azure-mgmt-resource             23.1.0b2

Python location '/usr/bin/python3.9'
Extensions directory '/home/dominique/.azure/cliextensions'
Extensions system directory '/usr/lib/python3.9/site-packages/azure-cli-extensions'

Python (Linux) 3.9.14 (main, Oct 12 2023, 19:48:32) 
[GCC 11.2.0]

Additional context

Seems that the issue is comes from lines like:

self.login_username = run_cli_cmd(`az account show').get("user")

run_cli_cmd will try to parse the command's output as JSON and revert to returning the bytes if it fails.

[yonzhan]

Thank you for opening this issue, we will look into it.