mirror of https://github.com/apache/druid.git
288 lines
9.7 KiB
Python
288 lines
9.7 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import requests
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from druidapi.util import dict_get
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from urllib.parse import quote
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from druidapi.error import ClientError
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def check_error(response):
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'''
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Raises an HttpError from the requests library if the response code is neither
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OK (200) nor Accepted (202).
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Druid's REST API is inconsistent with how it reports errors. Some APIs return
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an error as a JSON object. Others return a text message. Still others return
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nothing at all. With the JSON format, sometimes the error returns an
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'errorMessage' field, other times only a generic 'error' field.
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This method attempts to parse these variations. If the error response JSON
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matches one of the known error formats, then raises a `ClientError` with the error
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message. Otherise, raises a Requests library `HTTPError` for a generic error.
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If the response includes a JSON payload, then the it is returned in the json field
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of the `HTTPError` object so that the client can perhaps decode it.
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'''
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code = response.status_code
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if code == requests.codes.ok or code == requests.codes.accepted:
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return
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json = None
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try:
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json = response.json()
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except Exception:
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# If we can't get the JSON, raise a Requests error
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response.raise_for_status()
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# Druid JSON payload. Try to make sense of the error
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msg = dict_get(json, 'errorMessage')
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if not msg:
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msg = dict_get(json, 'error')
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if msg:
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# We have an explanation from Druid. Raise a Client exception
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raise ClientError(msg)
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# Don't know what the Druid JSON is. Raise a Requests exception, but
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# add on the JSON in the hopes that the caller can make use of it.
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try:
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response.raise_for_status()
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except Exception as e:
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e.json = json
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raise e
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def build_url(endpoint, req, args=None) -> str:
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'''
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Returns the full URL for a REST call given the relative request API and
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optional parameters to fill placeholders within the request URL.
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Parameters
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----------
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endpoint: str
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The base URL for the service.
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req: str
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Relative URL, with optional {} placeholders
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args: list
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Optional list of values to match {} placeholders in the URL.
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'''
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url = endpoint + req
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if args:
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quoted = [quote(arg) for arg in args]
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url = url.format(*quoted)
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return url
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class DruidRestClient:
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'''
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Wrapper around the basic Druid REST API operations using the
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requests Python package. Handles the grunt work of building up
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URLs, working with JSON, etc.
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The REST client accepts an endpoint that represents a Druid service, typically
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the Router. All requests are made to this service, which means using the service
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URL as the base. That is, if the service is http://localhost:8888, then
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a request for status is just '/status': the methods here build up the URL by
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concatenating the service endpoint with the request URL.
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'''
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def __init__(self, endpoint, auth=None):
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'''
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Creates a Druid rest client endpoint using the given endpoint URI and
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optional authentication.
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Parameters
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----------
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endpoint: str
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The Druid router endpoint of the form `'server:port'`. Use
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`'localhost:8888'` for a Druid instance running locally.
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auth: str, default = None
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Optional authorization credentials in the format described
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by the Requests library. For Basic auth use
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`auth=('user', 'password')`
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'''
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self.endpoint = endpoint
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self.trace = False
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self.session = requests.Session()
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if auth:
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self.session.auth = auth
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def enable_trace(self, flag=True):
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self.trace = flag
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def build_url(self, req, args=None) -> str:
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'''
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Returns the full URL for a REST call given the relative request API and
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optional parameters to fill placeholders within the request URL.
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Parameters
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----------
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req: str
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Relative URL, with optional {} placeholders
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args: list
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Optional list of values to match {} placeholders in the URL.
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'''
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return build_url(self.endpoint, req, args)
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def get(self, req, args=None, params=None, require_ok=True) -> requests.Request:
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'''
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Generic GET request to this service.
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Parameters
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----------
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req: str
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The request URL without host, port or query string.
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Example: `/status`
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args: [str], default = None
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Optional parameters to fill in to the URL.
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Example: `/customer/{}`
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params: dict, default = None
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Optional map of query variables to send in
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the URL. Query parameters are the name/value pairs
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that appear after the `?` marker.
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require_ok: bool, default = True
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Whether to require an OK (200) response. If `True`, and
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the request returns a different response code, then raises
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a `RestError` exception.
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Returns
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-------
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The `requests` `Request` object.
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'''
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url = self.build_url(req, args)
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if self.trace:
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print('GET:', url)
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r = self.session.get(url, params=params)
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if require_ok:
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check_error(r)
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return r
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def get_json(self, url_tail, args=None, params=None):
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'''
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Generic GET request which expects a JSON response.
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'''
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r = self.get(url_tail, args, params)
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return r.json()
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def post(self, req, body, args=None, headers=None, require_ok=True) -> requests.Response:
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'''
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Issues a POST request for the given URL on this
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node, with the given payload and optional URL query
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parameters.
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'''
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url = self.build_url(req, args)
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if self.trace:
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print('POST:', url)
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print('body:', body)
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r = self.session.post(url, data=body, headers=headers)
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if require_ok:
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check_error(r)
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return r
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def post_json(self, req, body, args=None, headers=None, params=None) -> requests.Response:
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'''
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Issues a POST request for the given URL on this node, with a JSON request. Returns
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the JSON response.
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Parameters
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----------
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req: str
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URL relative to the service base URL.
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body: any
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JSON-encodable Python object to send in the request body.
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args: array[str], default = None
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Arguments to include in the relative URL to replace {} markers.
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headers: dict, default = None
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Additional HTTP header fields to send in the request.
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params: dict, default = None
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Parameters to inlude in the URL as the `?name=value` query string.
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Returns
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-------
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The JSON response as a Python object.
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See
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---
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`post_only_json()` for the form that returns the response object, not JSON.
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'''
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r = self.post_only_json(req, body, args, headers, params)
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check_error(r)
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return r.json()
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def post_only_json(self, req, body, args=None, headers=None, params=None, require_ok=True) -> requests.Request:
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'''
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Issues a POST request for the given URL on this node, with a JSON request, returning
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the Requests library `Response` object.
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Parameters
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----------
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req: str
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URL relative to the service base URL.
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body: any
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JSON-encodable Python object to send in the request body.
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args: array[str], default = None
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Arguments to include in the relative URL to replace {} markers.
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headers: dict, default = None
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Additional HTTP header fields to send in the request.
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params: dict, default = None
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Parameters to inlude in the URL as the `?name=value` query string.
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Returns
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-------
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The JSON response as a Python object.
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See
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---
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`post_json()` for the form that returns the response JSON.
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'''
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url = self.build_url(req, args)
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if self.trace:
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print('POST:', url)
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print('body:', body)
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r = self.session.post(url, json=body, headers=headers, params=params)
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if require_ok:
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check_error(r)
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return r
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def delete(self, req, args=None, params=None, headers=None, require_ok=True):
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url = self.build_url(req, args)
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if self.trace:
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print('DELETE:', url)
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r = self.session.delete(url, params=params, headers=headers)
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if require_ok:
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check_error(r)
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return r
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def delete_json(self, req, args=None, params=None, headers=None):
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return self.delete(req, args=args, params=params, headers=headers).json()
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def close(self):
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'''
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Close the session. Use in scripts and tests when the system will otherwise complain
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about open sockets.
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'''
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self.session.close()
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self.session = None
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