airflow webserver_command 源码
airflow webserver_command 代码
文件路径：/airflow/cli/commands/webserver_command.py
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
"""Webserver command"""
from __future__ import annotations
import hashlib
import logging
import os
import signal
import subprocess
import sys
import textwrap
import time
from contextlib import suppress
from time import sleep
from typing import NoReturn
import daemon
import psutil
from daemon.pidfile import TimeoutPIDLockFile
from lockfile.pidlockfile import read_pid_from_pidfile
from airflow import settings
from airflow.configuration import conf
from airflow.exceptions import AirflowException, AirflowWebServerTimeout
from airflow.utils import cli as cli_utils
from airflow.utils.cli import setup_locations, setup_logging
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.process_utils import check_if_pidfile_process_is_running
log = logging.getLogger(__name__)
class GunicornMonitor(LoggingMixin):
"""
Runs forever, monitoring the child processes of @gunicorn_master_proc and
restarting workers occasionally or when files in the plug-in directory
has been modified.
Each iteration of the loop traverses one edge of this state transition
diagram, where each state (node) represents
[ num_ready_workers_running / num_workers_running ]. We expect most time to
be spent in [n / n]. `bs` is the setting webserver.worker_refresh_batch_size.
The horizontal transition at ? happens after the new worker parses all the
dags (so it could take a while!)
V ────────────────────────────────────────────────────────────────────────┐
[n / n] ──TTIN──> [ [n, n+bs) / n + bs ] ────?───> [n + bs / n + bs] ──TTOU─┘
^ ^───────────────┘
│
│ ┌────────────────v
└──────┴────── [ [0, n) / n ] <─── start
We change the number of workers by sending TTIN and TTOU to the gunicorn
master process, which increases and decreases the number of child workers
respectively. Gunicorn guarantees that on TTOU workers are terminated
gracefully and that the oldest worker is terminated.
:param gunicorn_master_pid: PID for the main Gunicorn process
:param num_workers_expected: Number of workers to run the Gunicorn web server
:param master_timeout: Number of seconds the webserver waits before killing gunicorn master that
doesn't respond
:param worker_refresh_interval: Number of seconds to wait before refreshing a batch of workers.
:param worker_refresh_batch_size: Number of workers to refresh at a time. When set to 0, worker
refresh is disabled. When nonzero, airflow periodically refreshes webserver workers by
bringing up new ones and killing old ones.
:param reload_on_plugin_change: If set to True, Airflow will track files in plugins_folder directory.
When it detects changes, then reload the gunicorn.
"""
def __init__(
self,
gunicorn_master_pid: int,
num_workers_expected: int,
master_timeout: int,
worker_refresh_interval: int,
worker_refresh_batch_size: int,
reload_on_plugin_change: bool,
):
super().__init__()
self.gunicorn_master_proc = psutil.Process(gunicorn_master_pid)
self.num_workers_expected = num_workers_expected
self.master_timeout = master_timeout
self.worker_refresh_interval = worker_refresh_interval
self.worker_refresh_batch_size = worker_refresh_batch_size
self.reload_on_plugin_change = reload_on_plugin_change
self._num_workers_running = 0
self._num_ready_workers_running = 0
self._last_refresh_time = time.monotonic() if worker_refresh_interval > 0 else None
self._last_plugin_state = self._generate_plugin_state() if reload_on_plugin_change else None
self._restart_on_next_plugin_check = False
def _generate_plugin_state(self) -> dict[str, float]:
"""
Generate dict of filenames and last modification time of all files in settings.PLUGINS_FOLDER
directory.
"""
if not settings.PLUGINS_FOLDER:
return {}
all_filenames: list[str] = []
for (root, _, filenames) in os.walk(settings.PLUGINS_FOLDER):
all_filenames.extend(os.path.join(root, f) for f in filenames)
plugin_state = {f: self._get_file_hash(f) for f in sorted(all_filenames)}
return plugin_state
@staticmethod
def _get_file_hash(fname: str):
"""Calculate MD5 hash for file"""
hash_md5 = hashlib.md5()
with open(fname, "rb") as f:
for chunk in iter(lambda: f.read(4096), b""):
hash_md5.update(chunk)
return hash_md5.hexdigest()
def _get_num_ready_workers_running(self) -> int:
"""Returns number of ready Gunicorn workers by looking for READY_PREFIX in process name"""
workers = psutil.Process(self.gunicorn_master_proc.pid).children()
def ready_prefix_on_cmdline(proc):
try:
cmdline = proc.cmdline()
if len(cmdline) > 0:
return settings.GUNICORN_WORKER_READY_PREFIX in cmdline[0]
except psutil.NoSuchProcess:
pass
return False
ready_workers = [proc for proc in workers if ready_prefix_on_cmdline(proc)]
return len(ready_workers)
def _get_num_workers_running(self) -> int:
"""Returns number of running Gunicorn workers processes"""
workers = psutil.Process(self.gunicorn_master_proc.pid).children()
return len(workers)
def _wait_until_true(self, fn, timeout: int = 0) -> None:
"""Sleeps until fn is true"""
start_time = time.monotonic()
while not fn():
if 0 < timeout <= time.monotonic() - start_time:
raise AirflowWebServerTimeout(f"No response from gunicorn master within {timeout} seconds")
sleep(0.1)
def _spawn_new_workers(self, count: int) -> None:
"""
Send signal to kill the worker.
:param count: The number of workers to spawn
"""
excess = 0
for _ in range(count):
# TTIN: Increment the number of processes by one
self.gunicorn_master_proc.send_signal(signal.SIGTTIN)
excess += 1
self._wait_until_true(
lambda: self.num_workers_expected + excess == self._get_num_workers_running(),
timeout=self.master_timeout,
)
def _kill_old_workers(self, count: int) -> None:
"""
Send signal to kill the worker.
:param count: The number of workers to kill
"""
for _ in range(count):
count -= 1
# TTOU: Decrement the number of processes by one
self.gunicorn_master_proc.send_signal(signal.SIGTTOU)
self._wait_until_true(
lambda: self.num_workers_expected + count == self._get_num_workers_running(),
timeout=self.master_timeout,
)
def _reload_gunicorn(self) -> None:
"""
Send signal to reload the gunicorn configuration. When gunicorn receive signals, it reload the
configuration, start the new worker processes with a new configuration and gracefully
shutdown older workers.
"""
# HUP: Reload the configuration.
self.gunicorn_master_proc.send_signal(signal.SIGHUP)
sleep(1)
self._wait_until_true(
lambda: self.num_workers_expected == self._get_num_workers_running(), timeout=self.master_timeout
)
def start(self) -> NoReturn:
"""Starts monitoring the webserver."""
try:
self._wait_until_true(
lambda: self.num_workers_expected == self._get_num_workers_running(),
timeout=self.master_timeout,
)
while True:
if not self.gunicorn_master_proc.is_running():
sys.exit(1)
self._check_workers()
# Throttle loop
sleep(1)
except (AirflowWebServerTimeout, OSError) as err:
self.log.error(err)
self.log.error("Shutting down webserver")
try:
self.gunicorn_master_proc.terminate()
self.gunicorn_master_proc.wait()
finally:
sys.exit(1)
def _check_workers(self) -> None:
num_workers_running = self._get_num_workers_running()
num_ready_workers_running = self._get_num_ready_workers_running()
# Whenever some workers are not ready, wait until all workers are ready
if num_ready_workers_running < num_workers_running:
self.log.debug(
'[%d / %d] Some workers are starting up, waiting...',
num_ready_workers_running,
num_workers_running,
)
sleep(1)
return
# If there are too many workers, then kill a worker gracefully by asking gunicorn to reduce
# number of workers
if num_workers_running > self.num_workers_expected:
excess = min(num_workers_running - self.num_workers_expected, self.worker_refresh_batch_size)
self.log.debug(
'[%d / %d] Killing %s workers', num_ready_workers_running, num_workers_running, excess
)
self._kill_old_workers(excess)
return
# If there are too few workers, start a new worker by asking gunicorn
# to increase number of workers
if num_workers_running < self.num_workers_expected:
self.log.error(
"[%d / %d] Some workers seem to have died and gunicorn did not restart them as expected",
num_ready_workers_running,
num_workers_running,
)
sleep(10)
num_workers_running = self._get_num_workers_running()
if num_workers_running < self.num_workers_expected:
new_worker_count = min(
self.num_workers_expected - num_workers_running, self.worker_refresh_batch_size
)
# log at info since we are trying fix an error logged just above
self.log.info(
'[%d / %d] Spawning %d workers',
num_ready_workers_running,
num_workers_running,
new_worker_count,
)
self._spawn_new_workers(new_worker_count)
return
# Now the number of running and expected worker should be equal
# If workers should be restarted periodically.
if self.worker_refresh_interval > 0 and self._last_refresh_time:
# and we refreshed the workers a long time ago, refresh the workers
last_refresh_diff = time.monotonic() - self._last_refresh_time
if self.worker_refresh_interval < last_refresh_diff:
num_new_workers = self.worker_refresh_batch_size
self.log.debug(
'[%d / %d] Starting doing a refresh. Starting %d workers.',
num_ready_workers_running,
num_workers_running,
num_new_workers,
)
self._spawn_new_workers(num_new_workers)
self._last_refresh_time = time.monotonic()
return
# if we should check the directory with the plugin,
if self.reload_on_plugin_change:
# compare the previous and current contents of the directory
new_state = self._generate_plugin_state()
# If changed, wait until its content is fully saved.
if new_state != self._last_plugin_state:
self.log.debug(
'[%d / %d] Plugins folder changed. The gunicorn will be restarted the next time the '
'plugin directory is checked, if there is no change in it.',
num_ready_workers_running,
num_workers_running,
)
self._restart_on_next_plugin_check = True
self._last_plugin_state = new_state
elif self._restart_on_next_plugin_check:
self.log.debug(
'[%d / %d] Starts reloading the gunicorn configuration.',
num_ready_workers_running,
num_workers_running,
)
self._restart_on_next_plugin_check = False
self._last_refresh_time = time.monotonic()
self._reload_gunicorn()
@cli_utils.action_cli
def webserver(args):
"""Starts Airflow Webserver"""
print(settings.HEADER)
# Check for old/insecure config, and fail safe (i.e. don't launch) if the config is wildly insecure.
if conf.get('webserver', 'secret_key') == 'temporary_key':
from rich import print as rich_print
rich_print(
"[red][bold]ERROR:[/bold] The `secret_key` setting under the webserver config has an insecure "
"value - Airflow has failed safe and refuses to start. Please change this value to a new, "
"per-environment, randomly generated string, for example using this command `[cyan]openssl rand "
"-hex 30[/cyan]`",
file=sys.stderr,
)
sys.exit(1)
access_logfile = args.access_logfile or conf.get('webserver', 'access_logfile')
error_logfile = args.error_logfile or conf.get('webserver', 'error_logfile')
access_logformat = args.access_logformat or conf.get('webserver', 'access_logformat')
num_workers = args.workers or conf.get('webserver', 'workers')
worker_timeout = args.worker_timeout or conf.get('webserver', 'web_server_worker_timeout')
ssl_cert = args.ssl_cert or conf.get('webserver', 'web_server_ssl_cert')
ssl_key = args.ssl_key or conf.get('webserver', 'web_server_ssl_key')
if not ssl_cert and ssl_key:
raise AirflowException('An SSL certificate must also be provided for use with ' + ssl_key)
if ssl_cert and not ssl_key:
raise AirflowException('An SSL key must also be provided for use with ' + ssl_cert)
from airflow.www.app import create_app
if args.debug:
print(f"Starting the web server on port {args.port} and host {args.hostname}.")
app = create_app(testing=conf.getboolean('core', 'unit_test_mode'))
app.run(
debug=True,
use_reloader=not app.config['TESTING'],
port=args.port,
host=args.hostname,
ssl_context=(ssl_cert, ssl_key) if ssl_cert and ssl_key else None,
)
else:
pid_file, stdout, stderr, log_file = setup_locations(
"webserver", args.pid, args.stdout, args.stderr, args.log_file
)
# Check if webserver is already running if not, remove old pidfile
check_if_pidfile_process_is_running(pid_file=pid_file, process_name="webserver")
print(
textwrap.dedent(
f'''\
Running the Gunicorn Server with:
Workers: {num_workers} {args.workerclass}
Host: {args.hostname}:{args.port}
Timeout: {worker_timeout}
Logfiles: {access_logfile} {error_logfile}
Access Logformat: {access_logformat}
================================================================='''
)
)
run_args = [
sys.executable,
'-m',
'gunicorn',
'--workers',
str(num_workers),
'--worker-class',
str(args.workerclass),
'--timeout',
str(worker_timeout),
'--bind',
args.hostname + ':' + str(args.port),
'--name',
'airflow-webserver',
'--pid',
pid_file,
'--config',
'python:airflow.www.gunicorn_config',
]
if args.access_logfile:
run_args += ['--access-logfile', str(args.access_logfile)]
if args.error_logfile:
run_args += ['--error-logfile', str(args.error_logfile)]
if args.access_logformat and args.access_logformat.strip():
run_args += ['--access-logformat', str(args.access_logformat)]
if args.daemon:
run_args += ['--daemon']
if ssl_cert:
run_args += ['--certfile', ssl_cert, '--keyfile', ssl_key]
run_args += ["airflow.www.app:cached_app()"]
gunicorn_master_proc = None
def kill_proc(signum, _):
log.info("Received signal: %s. Closing gunicorn.", signum)
gunicorn_master_proc.terminate()
with suppress(TimeoutError):
gunicorn_master_proc.wait(timeout=30)
if gunicorn_master_proc.poll() is not None:
gunicorn_master_proc.kill()
sys.exit(0)
def monitor_gunicorn(gunicorn_master_pid: int):
# Register signal handlers
signal.signal(signal.SIGINT, kill_proc)
signal.signal(signal.SIGTERM, kill_proc)
# These run forever until SIG{INT, TERM, KILL, ...} signal is sent
GunicornMonitor(
gunicorn_master_pid=gunicorn_master_pid,
num_workers_expected=num_workers,
master_timeout=conf.getint('webserver', 'web_server_master_timeout'),
worker_refresh_interval=conf.getint('webserver', 'worker_refresh_interval', fallback=30),
worker_refresh_batch_size=conf.getint('webserver', 'worker_refresh_batch_size', fallback=1),
reload_on_plugin_change=conf.getboolean(
'webserver', 'reload_on_plugin_change', fallback=False
),
).start()
if args.daemon:
# This makes possible errors get reported before daemonization
os.environ['SKIP_DAGS_PARSING'] = 'True'
app = create_app(None)
os.environ.pop('SKIP_DAGS_PARSING')
handle = setup_logging(log_file)
base, ext = os.path.splitext(pid_file)
with open(stdout, 'a') as stdout, open(stderr, 'a') as stderr:
stdout.truncate(0)
stderr.truncate(0)
ctx = daemon.DaemonContext(
pidfile=TimeoutPIDLockFile(f"{base}-monitor{ext}", -1),
files_preserve=[handle],
stdout=stdout,
stderr=stderr,
umask=int(settings.DAEMON_UMASK, 8),
)
with ctx:
subprocess.Popen(run_args, close_fds=True)
# Reading pid of gunicorn master as it will be different that
# the one of process spawned above.
while True:
sleep(0.1)
gunicorn_master_proc_pid = read_pid_from_pidfile(pid_file)
if gunicorn_master_proc_pid:
break
# Run Gunicorn monitor
gunicorn_master_proc = psutil.Process(gunicorn_master_proc_pid)
monitor_gunicorn(gunicorn_master_proc.pid)
else:
with subprocess.Popen(run_args, close_fds=True) as gunicorn_master_proc:
monitor_gunicorn(gunicorn_master_proc.pid)
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