Source code for locust.web

from __future__ import annotations
import csv
import logging
import os.path
from functools import wraps

from html import escape
from io import StringIO
from json import dumps
from itertools import chain
from time import time
from typing import TYPE_CHECKING, Optional, Any, Dict, List

import gevent
from flask import Flask, make_response, jsonify, render_template, request, send_file, Response, send_from_directory
from flask_basicauth import BasicAuth
from gevent import pywsgi

from .exception import AuthCredentialsError
from .runners import MasterRunner, STATE_RUNNING, STATE_MISSING
from .log import greenlet_exception_logger
from .stats import StatsCSVFileWriter, StatsErrorDict, sort_stats
from . import stats as stats_module, __version__ as version, argument_parser
from .stats import StatsCSV
from .user.inspectuser import get_ratio
from .util.cache import memoize
from .util.timespan import parse_timespan
from .html import get_html_report
from flask_cors import CORS

    from .env import Environment

logger = logging.getLogger(__name__)
greenlet_exception_handler = greenlet_exception_logger(logger)


[docs]class WebUI: """ Sets up and runs a Flask web app that can start and stop load tests using the :attr:`environment.runner <locust.env.Environment.runner>` as well as show the load test statistics in :attr:`environment.stats <locust.env.Environment.stats>` """ app: Optional[Flask] = None """ Reference to the :class:`flask.Flask` app. Can be used to add additional web routes and customize the Flask app in other various ways. Example:: from flask import request"/my_custom_route") def my_custom_route(): return "your IP is: %s" % request.remote_addr """ greenlet: Optional[gevent.Greenlet] = None """ Greenlet of the running web server """ server: Optional[pywsgi.WSGIServer] = None """Reference to the :class:`pyqsgi.WSGIServer` instance""" template_args: Dict[str, Any] """Arguments used to render index.html for the web UI. Must be used with custom templates extending index.html.""" def __init__( self, environment: "Environment", host: str, port: int, auth_credentials: Optional[str] = None, tls_cert: Optional[str] = None, tls_key: Optional[str] = None, stats_csv_writer: Optional[StatsCSV] = None, delayed_start=False, userclass_picker_is_active=False, modern_ui=False, ): """ Create WebUI instance and start running the web server in a separate greenlet (self.greenlet) Arguments: environment: Reference to the current Locust Environment host: Host/interface that the web server should accept connections to port: Port that the web server should listen to auth_credentials: If provided, it will enable basic auth with all the routes protected by default. Should be supplied in the format: "user:pass". tls_cert: A path to a TLS certificate tls_key: A path to a TLS private key delayed_start: Whether or not to delay starting web UI until `start()` is called. Delaying web UI start allows for adding Flask routes or Blueprints before accepting requests, avoiding errors. """ environment.web_ui = self self.stats_csv_writer = stats_csv_writer or StatsCSV(environment, stats_module.PERCENTILES_TO_REPORT) self.environment = environment = host self.port = port self.tls_cert = tls_cert self.tls_key = tls_key self.userclass_picker_is_active = userclass_picker_is_active self.modern_ui = modern_ui app = Flask(__name__) CORS(app) = app app.jinja_env.add_extension("") app.debug = True self.root_path = os.path.dirname(os.path.abspath(__file__)) app.root_path = self.root_path self.webui_build_path = f"{self.root_path}/webui/dist"["BASIC_AUTH_ENABLED"] = False self.auth: Optional[BasicAuth] = None self.greenlet: Optional[gevent.Greenlet] = None self._swarm_greenlet: Optional[gevent.Greenlet] = None self.template_args = {} if auth_credentials is not None: credentials = auth_credentials.split(":") if len(credentials) == 2:["BASIC_AUTH_USERNAME"] = credentials[0]["BASIC_AUTH_PASSWORD"] = credentials[1]["BASIC_AUTH_ENABLED"] = True self.auth = BasicAuth() self.auth.init_app( else: raise AuthCredentialsError( "Invalid auth_credentials. It should be a string in the following format: 'user:pass'" ) if environment.runner: self.update_template_args() if not delayed_start: self.start() @app.errorhandler(Exception) def handle_exception(error): error_message = str(error) logger.log(logging.CRITICAL, error_message) return make_response(error_message, 500) @app.route("/assets/<path:path>") def send_assets(path): webui_build_path = self.webui_build_path return send_from_directory(f"{webui_build_path}/assets", path) @app.route("/") @self.auth_required_if_enabled def index() -> str | Response: if not environment.runner: return make_response("Error: Locust Environment does not have any runner", 500) self.update_template_args() if self.modern_ui: self.set_static_modern_ui() return render_template("index.html", template_args=self.template_args) return render_template("index.html", **self.template_args) @app.route("/swarm", methods=["POST"]) @self.auth_required_if_enabled def swarm() -> Response: assert request.method == "POST" # Loading UserClasses & ShapeClasses if Locust is running with UserClass Picker if self.userclass_picker_is_active: if not self.environment.available_user_classes: err_msg = "UserClass picker is active but there are no available UserClasses" return jsonify({"success": False, "message": err_msg, "host":}) # Getting Specified User Classes form_data_user_class_names = request.form.getlist("user_classes") # Updating UserClasses if form_data_user_class_names: user_classes = {} for user_class_name, user_class_object in self.environment.available_user_classes.items(): if user_class_name in form_data_user_class_names: user_classes[user_class_name] = user_class_object else: if self.environment.runner and self.environment.runner.state == STATE_RUNNING: # Test is already running # Using the user classes that have already been selected user_classes = { key: value for (key, value) in self.environment.available_user_classes.items() if value in self.environment.user_classes } else: # Starting test with no user class selection # Defaulting to using all available user classes user_classes = self.environment.available_user_classes self._update_user_classes(user_classes) # Updating ShapeClass if specified in WebUI Form form_data_shape_class_name = request.form.get("shape_class", "Default") if form_data_shape_class_name == "Default": self._update_shape_class(None) else: self._update_shape_class(form_data_shape_class_name) parsed_options_dict = vars(environment.parsed_options) if environment.parsed_options else {} run_time = None for key, value in request.form.items(): if key == "user_count": # if we just renamed this field to "users" we wouldn't need this user_count = int(value) elif key == "spawn_rate": spawn_rate = float(value) elif key == "host": # Replace < > to guard against XSS = str(request.form["host"]).replace("<", "").replace(">", "") elif key == "user_classes": # Set environment.parsed_options.user_classes to the selected user_classes parsed_options_dict[key] = request.form.getlist("user_classes") elif key == "run_time": if not value: continue try: run_time = parse_timespan(value) except ValueError: err_msg = "Valid run_time formats are : 20, 20s, 3m, 2h, 1h20m, 3h30m10s, etc." logger.error(err_msg) return jsonify({"success": False, "message": err_msg, "host":}) elif key in parsed_options_dict: # update the value in environment.parsed_options, but dont change the type. # This won't work for parameters that are None parsed_options_dict[key] = type(parsed_options_dict[key])(value) if environment.shape_class and environment.runner is not None: environment.runner.start_shape() return jsonify( { "success": True, "message": f"Swarming started using shape class '{type(environment.shape_class).__name__}'", "host":, } ) if self._swarm_greenlet is not None: self._swarm_greenlet.kill(block=True) self._swarm_greenlet = None if environment.runner is not None: self._swarm_greenlet = gevent.spawn(environment.runner.start, user_count, spawn_rate) self._swarm_greenlet.link_exception(greenlet_exception_handler) response_data = { "success": True, "message": "Swarming started", "host":, } if run_time: gevent.spawn_later(run_time, self._stop_runners).link_exception(greenlet_exception_handler) response_data["run_time"] = run_time if self.userclass_picker_is_active: response_data["user_classes"] = sorted(user_classes.keys()) return jsonify(response_data) else: return jsonify({"success": False, "message": "No runner", "host":}) @app.route("/stop") @self.auth_required_if_enabled def stop() -> Response: if self._swarm_greenlet is not None: self._swarm_greenlet.kill(block=True) self._swarm_greenlet = None if environment.runner is not None: environment.runner.stop() return jsonify({"success": True, "message": "Test stopped"}) @app.route("/stats/reset") @self.auth_required_if_enabled def reset_stats() -> str: if environment.runner is not None: environment.runner.stats.reset_all() environment.runner.exceptions = {} return "ok" @app.route("/stats/report") @self.auth_required_if_enabled def stats_report() -> Response: if self.modern_ui: self.set_static_modern_ui() static_path = f"{self.webui_build_path}/assets" else: static_path = f"{self.root_path}/static" theme = request.args.get("theme", "") res = get_html_report( self.environment, static_path=static_path, show_download_link=not request.args.get("download"), use_modern_ui=self.modern_ui, theme=theme, ) if request.args.get("download"): res = app.make_response(res) res.headers["Content-Disposition"] = f"attachment;filename=report_{time()}.html" return res def _download_csv_suggest_file_name(suggest_filename_prefix: str) -> str: """Generate csv file download attachment filename suggestion. Arguments: suggest_filename_prefix: Prefix of the filename to suggest for saving the download. Will be appended with timestamp. """ return f"{suggest_filename_prefix}_{time()}.csv" def _download_csv_response(csv_data: str, filename_prefix: str) -> Response: """Generate csv file download response with 'csv_data'. Arguments: csv_data: CSV header and data rows. filename_prefix: Prefix of the filename to suggest for saving the download. Will be appended with timestamp. """ response = make_response(csv_data) response.headers["Content-type"] = "text/csv" response.headers[ "Content-disposition" ] = f"attachment;filename={_download_csv_suggest_file_name(filename_prefix)}" return response @app.route("/stats/requests/csv") @self.auth_required_if_enabled def request_stats_csv() -> Response: data = StringIO() writer = csv.writer(data) self.stats_csv_writer.requests_csv(writer) return _download_csv_response(data.getvalue(), "requests") @app.route("/stats/requests_full_history/csv") @self.auth_required_if_enabled def request_stats_full_history_csv() -> Response: options = self.environment.parsed_options if options and options.stats_history_enabled and isinstance(self.stats_csv_writer, StatsCSVFileWriter): return send_file( os.path.abspath(self.stats_csv_writer.stats_history_file_name()), mimetype="text/csv", as_attachment=True, download_name=_download_csv_suggest_file_name("requests_full_history"), etag=True, max_age=0, conditional=True, last_modified=None, ) return make_response("Error: Server was not started with option to generate full history.", 404) @app.route("/stats/failures/csv") @self.auth_required_if_enabled def failures_stats_csv() -> Response: data = StringIO() writer = csv.writer(data) self.stats_csv_writer.failures_csv(writer) return _download_csv_response(data.getvalue(), "failures") @app.route("/stats/requests") @self.auth_required_if_enabled @memoize(timeout=DEFAULT_CACHE_TIME, dynamic_timeout=True) def request_stats() -> Response: stats: List[Dict[str, Any]] = [] errors: List[StatsErrorDict] = [] if environment.runner is None: report = { "stats": stats, "errors": errors, "total_rps": 0.0, "fail_ratio": 0.0, "current_response_time_percentile_1": None, "current_response_time_percentile_2": None, "state": STATE_MISSING, "user_count": 0, } if isinstance(environment.runner, MasterRunner): report.update({"workers": []}) return jsonify(report) for s in chain(sort_stats(environment.runner.stats.entries), []): stats.append(s.to_dict()) for e in environment.runner.errors.values(): err_dict = e.serialize() err_dict["name"] = escape(err_dict["name"]) err_dict["error"] = escape(err_dict["error"]) errors.append(err_dict) # Truncate the total number of stats and errors displayed since a large number of rows will cause the app # to render extremely slowly. Aggregate stats should be preserved. truncated_stats = stats[:500] if len(stats) > 500: truncated_stats += [stats[-1]] report = {"stats": truncated_stats, "errors": errors[:500]} if stats: report["total_rps"] = stats[len(stats) - 1]["current_rps"] report["fail_ratio"] = report[ "current_response_time_percentile_1" ] = stats_module.PERCENTILES_TO_CHART[0] ) report[ "current_response_time_percentile_2" ] = stats_module.PERCENTILES_TO_CHART[1] ) if isinstance(environment.runner, MasterRunner): workers = [] for worker in environment.runner.clients.values(): workers.append( { "id":, "state": worker.state, "user_count": worker.user_count, "cpu_usage": worker.cpu_usage, "memory_usage": worker.memory_usage, } ) report["workers"] = workers report["state"] = environment.runner.state report["user_count"] = environment.runner.user_count return jsonify(report) @app.route("/exceptions") @self.auth_required_if_enabled def exceptions() -> Response: return jsonify( { "exceptions": [ { "count": row["count"], "msg": escape(row["msg"]), "traceback": escape(row["traceback"]), "nodes": ", ".join(row["nodes"]), } for row in (environment.runner.exceptions.values() if environment.runner is not None else []) ] } ) @app.route("/exceptions/csv") @self.auth_required_if_enabled def exceptions_csv() -> Response: data = StringIO() writer = csv.writer(data) self.stats_csv_writer.exceptions_csv(writer) return _download_csv_response(data.getvalue(), "exceptions") @app.route("/tasks") @self.auth_required_if_enabled def tasks() -> Dict[str, Dict[str, Dict[str, float]]]: runner = self.environment.runner user_spawned: Dict[str, int] if runner is None: user_spawned = {} else: user_spawned = ( runner.reported_user_classes_count if isinstance(runner, MasterRunner) else runner.user_classes_count ) task_data = { "per_class": get_ratio(self.environment.user_classes, user_spawned, False), "total": get_ratio(self.environment.user_classes, user_spawned, True), } return task_data @app.route("/logs") @self.auth_required_if_enabled def logs(): log_reader_handler = [ handler for handler in logging.getLogger("root").handlers if == "log_reader" ] if log_reader_handler: logs = log_reader_handler[0].logs else: logs = [] return jsonify({"logs": logs}) def start(self): self.greenlet = gevent.spawn(self.start_server) self.greenlet.link_exception(greenlet_exception_handler) def start_server(self): if self.tls_cert and self.tls_key: self.server = pywsgi.WSGIServer( (, self.port),, log=None, keyfile=self.tls_key, certfile=self.tls_cert ) else: self.server = pywsgi.WSGIServer((, self.port),, log=None) self.server.serve_forever()
[docs] def stop(self): """ Stop the running web server """ self.server.stop()
[docs] def auth_required_if_enabled(self, view_func): """ Decorator that can be used on custom route methods that will turn on Basic Auth authentication if the ``--web-auth`` flag is used. Example::"/my_custom_route") @web_ui.auth_required_if_enabled def my_custom_route(): return "custom response" """ @wraps(view_func) def wrapper(*args, **kwargs): if["BASIC_AUTH_ENABLED"]: if self.auth.authenticate(): return view_func(*args, **kwargs) else: return self.auth.challenge() else: return view_func(*args, **kwargs) return wrapper
def set_static_modern_ui(self): = self.webui_build_path = f"{self.webui_build_path}/assets/" = "/assets/" def update_template_args(self): override_host_warning = False if host = elif self.environment.runner.user_classes: all_hosts = { for l in self.environment.runner.user_classes} if len(all_hosts) == 1: host = list(all_hosts)[0] else: # since we have multiple User classes with different host attributes, we'll # inform that specifying host will override the host for all User classes override_host_warning = True host = None else: host = None options = self.environment.parsed_options is_distributed = isinstance(self.environment.runner, MasterRunner) if is_distributed: worker_count = self.environment.runner.worker_count else: worker_count = 0 stats = self.environment.runner.stats extra_options = argument_parser.ui_extra_args_dict() available_user_classes = ( None if not self.environment.available_user_classes else sorted(self.environment.available_user_classes) ) available_shape_classes = ["Default"] if self.environment.available_shape_classes: available_shape_classes += sorted(self.environment.available_shape_classes.keys()) self.template_args = { "locustfile": self.environment.locustfile, "state": self.environment.runner.state, "is_distributed": is_distributed, "user_count": self.environment.runner.user_count, "version": version, "host": host if host else "", "history": stats.history if stats.num_requests > 0 else {}, "override_host_warning": override_host_warning, "num_users": options and options.num_users, "spawn_rate": options and options.spawn_rate, "worker_count": worker_count, "hide_common_options": ( self.environment.shape_class and not (self.userclass_picker_is_active or self.environment.shape_class.use_common_options) ), "stats_history_enabled": options and options.stats_history_enabled, "tasks": dumps({}), "extra_options": extra_options, "run_time": options and options.run_time, "show_userclass_picker": self.userclass_picker_is_active, "available_user_classes": available_user_classes, "available_shape_classes": available_shape_classes, "percentile1": stats_module.PERCENTILES_TO_CHART[0], "percentile2": stats_module.PERCENTILES_TO_CHART[1], } def _update_shape_class(self, shape_class_name): if shape_class_name: shape_class = self.environment.available_shape_classes[shape_class_name] else: shape_class = None # Validating ShapeClass self.environment.shape_class = shape_class self.environment._validate_shape_class_instance() def _update_user_classes(self, user_classes): self.environment.user_classes = list(user_classes.values()) # populate the locustfile which used in web ui title only if self.environment.locustfile is None: self.environment.locustfile = ",".join(self.environment.user_classes_by_name.keys()) # Validating UserClasses self.environment._remove_user_classes_with_weight_zero() self.environment._validate_user_class_name_uniqueness() def _stop_runners(self): self.environment.runner.stop()