Files
zulip/zerver/lib/openapi.py
Steve Howell 67e2fd5900 Minimize race conditions for reading zulip.yaml.
In the event that two processes are racing to be the
first to load data from zulip.yaml, we now make the
race scenario be duplicated effort instead of having
the second racer get an attribute error on `data`.

We do this by declaring victory only after setting
`data`.  "Declaring victory" in this case is a matter
of setting `last_update`.

We are still possibly vulnerable to corrupted data
here, so we should investigate a mutex, or just
read the data on every call (but it's strangely
expensive, almost 3.5s on my instance), or converting
the YAML to code before launching the server.
2018-09-12 11:07:20 -07:00

121 lines
4.4 KiB
Python

# Set of helper functions to manipulate the OpenAPI files that define our REST
# API's specification.
import os
from typing import Any, Dict, List, Optional
OPENAPI_SPEC_PATH = os.path.abspath(os.path.join(
os.path.dirname(__file__),
'../openapi/zulip.yaml'))
# A list of exceptions we allow when running validate_against_openapi_schema.
# The validator will ignore these keys when they appear in the "content"
# passed.
EXCLUDE_PROPERTIES = {
'/register': {
'post': {
'200': ['max_message_id', 'realm_emoji']
}
}
}
class OpenAPISpec():
def __init__(self, path: str) -> None:
self.path = path
self.last_update = None # type: Optional[float]
self.data = None
def reload(self) -> None:
# Because importing yamole (and in turn, yaml) takes
# significant time, and we only use python-yaml for our API
# docs, importing it lazily here is a significant optimization
# to `manage.py` startup.
#
# There is a bit of a race here...we may have two processes
# accessing this module level object and both trying to
# populate self.data at the same time. Hopefully this will
# only cause some extra processing at startup and not data
# corruption.
from yamole import YamoleParser
with open(self.path) as f:
yaml_parser = YamoleParser(f)
self.data = yaml_parser.data
self.last_update = os.path.getmtime(self.path)
def spec(self) -> Dict[str, Any]:
"""Reload the OpenAPI file if it has been modified after the last time
it was read, and then return the parsed data.
"""
last_modified = os.path.getmtime(self.path)
# Using != rather than < to cover the corner case of users placing an
# earlier version than the current one
if self.last_update != last_modified:
self.reload()
assert(self.data)
return self.data
class SchemaError(Exception):
pass
openapi_spec = OpenAPISpec(OPENAPI_SPEC_PATH)
def get_openapi_fixture(endpoint: str, method: str,
response: Optional[str]='200') -> Dict[str, Any]:
"""Fetch a fixture from the full spec object.
"""
return (openapi_spec.spec()['paths'][endpoint][method.lower()]['responses']
[response]['content']['application/json']['schema']
['example'])
def get_openapi_parameters(endpoint: str,
method: str) -> List[Dict[str, Any]]:
return (openapi_spec.spec()['paths'][endpoint][method.lower()]['parameters'])
def validate_against_openapi_schema(content: Dict[str, Any], endpoint: str,
method: str, response: str) -> None:
"""Compare a "content" dict with the defined schema for a specific method
in an endpoint.
"""
schema = (openapi_spec.spec()['paths'][endpoint][method.lower()]['responses']
[response]['content']['application/json']['schema'])
exclusion_list = (EXCLUDE_PROPERTIES.get(endpoint, {}).get(method, {})
.get(response, []))
for key, value in content.items():
# Ignore in the validation the keys in EXCLUDE_PROPERTIES
if key in exclusion_list:
continue
# Check that the key is defined in the schema
if key not in schema['properties']:
raise SchemaError('Extraneous key "{}" in the response\'s '
'content'.format(key))
# Check that the types match
expected_type = to_python_type(schema['properties'][key]['type'])
actual_type = type(value)
if expected_type is not actual_type:
raise SchemaError('Expected type {} for key "{}", but actually '
'got {}'.format(expected_type, key, actual_type))
# Check that at least all the required keys are present
for req_key in schema['required']:
if req_key not in content.keys():
raise SchemaError('Expected to find the "{}" required key')
def to_python_type(py_type: str) -> type:
"""Transform an OpenAPI-like type to a Pyton one.
https://swagger.io/docs/specification/data-models/data-types
"""
TYPES = {
'string': str,
'number': float,
'integer': int,
'boolean': bool,
'array': list,
'object': dict
}
return TYPES[py_type]