{Core} Print traceback to debug log when handle_exception is called

[jiasli]

Description

Print traceback to debug log when azure.cli.core.util.handle_exception is called. This can help identify where the exception is generated and thrown.

Testing Guide

Notice the location westu is wrong (should be westus):

> az group create -n rg1 -l westu --debug
...
azure.cli.core.util.handle_exception is called with an exception:
Traceback (most recent call last):
  File "D:\cli\env38\lib\site-packages\knack\cli.py", line 215, in invoke
    cmd_result = self.invocation.execute(args)
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\commands\__init__.py", line 654, in execute
    raise ex
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\commands\__init__.py", line 718, in _run_jobs_serially
    results.append(self._run_job(expanded_arg, cmd_copy))
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\commands\__init__.py", line 711, in _run_job
    six.reraise(*sys.exc_info())
  File "D:\cli\env38\lib\site-packages\six.py", line 703, in reraise
    raise value
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\commands\__init__.py", line 688, in _run_job
    result = cmd_copy(params)
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\commands\__init__.py", line 325, in __call__
    return self.handler(*args, **kwargs)
  File "d:\cli\azure-cli\src\azure-cli-core\azure\cli\core\__init__.py", line 776, in default_command_handler
    return op(**command_args)
  File "d:\cli\azure-cli\src\azure-cli\azure\cli\command_modules\resource\custom.py", line 1082, in create_resource_group
    return rcf.resource_groups.create_or_update(rg_name, parameters)
  File "d:\cli\env38\lib\site-packages\azure\mgmt\resource\resources\v2020_06_01\operations\_resource_groups_operations.py", line 154, in create_or_update
    raise exp
msrestazure.azure_exceptions.CloudError: Azure Error: LocationNotAvailableForResourceGroup
Message: The provided location 'westu' is not available for resource group. List of available regions is 'centralus,eastasia,southeastasia,eastus,eastus2,westus,westus2,northcentralus,southcentralus,westcentralus,northeurope,westeurope,japaneast,japanwest,brazilsouth,australiasoutheast,australiaeast,westindia,southindia,centralindia,canadacentral,canadaeast,uksouth,ukwest,koreacentral,koreasouth,francecentral,southafricanorth,uaenorth,australiacentral,switzerlandnorth,germanywestcentral,norwayeast,eastus2euap,centraluseuap'.

[jiasli]

Capture requests.exceptions.SSLError which is generated by directly calling requests's methods.

[haroldrandom]

Will msrest capture SSLError?

[jiasli]

Yes. It will be thrown as ClientRequestError.

[yonzhan]

Core

[jiasli]

We still lack a good way to manage short links. Perhaps we need a meeting to discuss about how to manage them.

[jsntcy]

Is there any security concern to expose the whole traceback to users?
Usually we can store trackback in our telemetry, but just show meaningful messages to users.

[jiasli]

1. The traceback contains no sensitive information, but only the code flow. The value of parameters are not displayed.
2. The traceback only appears in the --debug log and is not sent anywhere. If the user wants to share it, he/she can filter it first.
3. On the contrary, using client telemetry would expose more security concern as the traceback is sent over the network if telemetry is turned on.
4. Using client telemetry would require us to identify the specific command execution from other millions of command executions.
5. Anyway, the client telemetry doesn't support sending debug log right now.

[qwordy]

Can you make sure the trace is of ex? ex is not used.

[jiasli]

format_exc prints the last exception (represented by sys.exc_info()), and when handle_exception is called, sys.exc_info() corresponds to ex.