maas 2.2 api returning malformed data

[rory schramm]

Hi I'm using python3 to query maas by api and most of them time I'm getting valid http/json data back from lib request. However, sometimes the data that I get back from the maas api is malformed.

here is the python script I'm using:

```
from requests_oauthlib import OAuth1 as oauth
import requests
import json

client_key = 'my_client_key'
client_secret = ''
res_key = 'my_resource_key'
res_secret = 'my_resource_secret'

def myq(url='http://127.0.0.1:5240/MAAS',uri='None'):
        headeroauth = oauth(client_key, client_secret, res_key,
        res_secret, signature_type = 'auth_header')
        r = requests.get(queryurl, auth = headeroauth)
        return r

r = myq(uri='/api/2.0/machines/ww4467/')
try:
    machine = yaml.load(r.text)
    m = {
            'hostname': machine['hostname']
        }
    print('good:', r,dir(r))

except Exception:
    print('bad:', r, dir(r))
    print(r.text)
```

also the librequests json object from the returned query throws the following exception if I try to use that as well when I get a malformed response.

ie

```
r = myq(uri='/api/2.0/machines/ww4467/')
machine = r.json()

Traceback (most recent call last):
  File "./pyapi.py", line 51, in <module>
    machine = r.json()
  File "/home/sysadmin/maas/lib/python3.5/site-packages/requests/models.py", line 892, in json
    return complexjson.loads(self.text, **kwargs)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
```

I don't see any errors in any of the mass log files or syslog.

[Mike Pontillo (mpontillo)]

I think this is a duplicate of an existing bug. (I'll link it if I find it.) You probably need to set an 'Accept' header to get consistent results. Long story short: MAAS makes use of a Python library that has some undefined behavior when you don't define one in your request, such as:

    Accept: application/json