st2 CLI does not return errors as JSON / YAML

SUMMARY

When running the st2 CLI command with -j,--jso or -y,--yaml and an error occurs, the errors are printed as strings and not JSON or YAML.

ISSUE TYPE

• Bug Report

STACKSTORM VERSION

$ st2 --version
st2 2.7.2, on Python 2.7

OS / ENVIRONMENT / INSTALL METHOD

$ cat /etc/redhat-release                                                                            
CentOS Linux release 7.5.1804 (Core) 

Install type = puppet-st2

STEPS TO REPRODUCE

$ st2 pack get --json fdsfdsfds
Traceback (most recent call last):
  File "/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/commands/resource.py", line 165, in get_resource_by_pk
    instance = self.manager.get_by_id(pk, **kwargs)
  File "/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py", line 40, in decorate
    return func(*args, **kwargs)
  File "/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py", line 204, in get_by_id
    self.handle_error(response)
  File "/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py", line 166, in handle_error
    response.raise_for_status()
  File "/opt/stackstorm/st2/lib/python2.7/site-packages/requests/models.py", line 928, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
HTTPError: 401 Client Error: Unauthorized
MESSAGE: Unauthorized - One of Token or API key required. for url: http://127.0.0.1:9101/v1/packs/fdsfdsfds
ERROR: 401 Client Error: Unauthorized
MESSAGE: Unauthorized - One of Token or API key required. for url: http://127.0.0.1:9101/v1/packs/fdsfdsfds
$ st2 login -j -w st2admin
Password: 
Logged in as st2admin
$ st2 pack get --json fdsfsdfsd
Pack "fdsfsdfsd" is not found.

EXPECTED RESULTS

Error messages to be formated as JSON / YAML so they can be parsed programatically.

Example:

$ st2 pack get --json fdsfsdfsd
{
  "success": false.
  "failed": true,
  "error": {
    "type": "pack_not_found",
    "message": "Pack \"fdsfsdfsd\" is not found."
  }
}

Example:

$ st2 pack get --json fdsfsdfsd
{
  "success": false.
  "failed": true,
  "error": {
    "type": "unauthorized",
    "http_status": 401,
    "message": "Unauthorized - One of Token or API key required. for url: http://127.0.0.1:9101/v1/packs/fdsfdsfds"
    "exception_type": "requests.HTTPError"
    "traceback": [
      "Traceback (most recent call last):",
      "  File \"/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/commands/resource.py\", line 165, in get_resource_by_pk",
      "    instance = self.manager.get_by_id(pk, **kwargs)",
      "  File \"/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py\", line 40, in decorate",
      "    return func(*args, **kwargs)",
      "  File \"/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py\", line 204, in get_by_id",
      "    self.handle_error(response)",
      "  File \"/opt/stackstorm/st2/lib/python2.7/site-packages/st2client/models/core.py\", line 166, in handle_error",
      "    response.raise_for_status()",
      "  File \"/opt/stackstorm/st2/lib/python2.7/site-packages/requests/models.py\", line 928, in raise_for_status",
      "    raise HTTPError(http_error_msg, response=self)"
    ]
  }
}

Start with the st2 CLI error path shown in st2client/commands/resource.py and st2client/models/core.py, especially get_resource_by_pk, get_by_id, and handle_error. Reproduce the unauthorized and missing-pack commands with --json and --yaml, then verify that failures are emitted as parseable JSON or YAML with the requested error details.