Interacting with JSON-based APIs from the command line can be difficult, and OpenStack is filled with REST APIs that consume or produce JSON. I've just put pair of tools for generating and filtering JSON on the command line, called collectively json-tools.

Both make use of the Python dpath module to populate or filter JSON objects.

The jsong command generates JSON on stdout. You provide /-delimited paths on the command line to represent the JSON structure. For example, if you run:

$ jsong auth/passwordCredentials/username=admin \
  auth/passwordCredentials/password=secret

You get:

{
    "auth": {
        "passwordCredentials": {
            "username": "admin", 
            "password": "secret"
        }
    }
}

The jsonx command accepts JSON on stdin and selects subtrees or values for output on stdout. Given the above output, you could extract the password with:

jsonx -v auth/passwordCredentials/password

Which would give you:

secret

The -v flag here indicates that you only want the values of matched paths; without the -v the output would have been:

auth/passwordCredentials/password secret

There are more examples -- including some use of the OpenStack APIs -- in the README document.