"No JSON object could be decoded" when writing to KV v2

[justyns]

Versions

• hvac==0.6.4
• Vault v0.11.1 ('8575f8fedcf8f5a6eb2b4701cb527b99574b5286')

Problem

I'm currently running into a weird issue where I am attempting to write secrets to the kv v2 api, and it is returning an error.

Example script

This is an example of what I'm doing:

import os
import hvac

vault_url = os.environ.get('VAULT_ADDR', 'http:https://127.0.0.1:8200')
vault_token = os.environ.get('VAULT_TOKEN')
vault_secret_prefix = 'test/demoapp/'

client = hvac.Client(url=vault_url, token=vault_token)

kv = client.kv.v2
kv.create_or_update_secret(
    path="{}secret2".format(vault_secret_prefix),
    secret=dict(foo='bar'))

Error

And this is the error:

Traceback (most recent call last):
  File "hvac-test.py", line 31, in <module>
    secret=dict(foo='bar'))
  File "/usr/local/lib/python2.7/site-packages/hvac/api/secrets_engines/kv_v2.py", line 124, in create_or_update_secret
    return response.json()
  File "/usr/local/lib/python2.7/site-packages/requests/models.py", line 896, in json
    return complexjson.loads(self.text, **kwargs)
  File "/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 382, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

Additional information

https://github.com/hvac/hvac/blob/master/hvac/api/secrets_engines/kv_v2.py#L124 looks like it always returns response.json() but after adding some debug statements to that function, the response from vault is a 204 and there's no data to parse.

Sidenote: The above error is from running vault in server mode. I tested using dev mode, and I do not get the same error. I haven't investigated why, but vault in dev mode apparently returns a response (with a 200 instead of 204) when it does not without dev mode. I might open a ticket on the vault repo for this if the docs don't mention it.

[justyns]

Update: This was my fault.. When you run vault in dev mode, it automatically enables V2 of the kv at /secret. I assumed the real server was also doing this, but the default behavior for that is to use v1 instead of v1.

I enabled versioning / kv v2 on the real server and it worked as expected.

Should I leave this open? I feel like there could at least be a better error message for this situation.

[jeffwecan]

@justyns: Totally agree that the exception raised in this case makes things more confusing than need be. Will see what we can do about raising a more helpful message in these cases... 👍