Tox has [released 4.9.0](https://github.com/tox-dev/tox/releases/tag/4.9.0) which fixed a bug where non existing environments did NOT fail, so since tox 4.9.0 they now DO fail: https://github.com/tox-dev/tox/issues/2858

We are relying on the previous behavior (the bugged one) so until we can fix it, I'm limiting tox as it breaks every PR right now which is worse than the limitation itself (which is not recommended).

We need to fix this soon so we can remove this limitation @auvipy @thedrow 
Limit tox to < 4.9. Tox has [released 4.9.0](https://github.com/tox-dev/tox/releases/tag/4.9.0) which fixed a bug where non existing environments did NOT fail, so since tox 4.9.0 they now DO fail: https://github.com/tox-dev/tox/issues/2858

We are relying on the previous behavior (the bugged one) so until we can fix it, I'm limiting tox as it breaks every PR right now which is worse than the limitation itself (which is not recommended).

We need to fix this soon so we can remove this limitation @auvipy @thedrow 
"""Utility to dump events to screen.

This is a simple program that dumps events to the console
as they happen.  Think of it like a `tcpdump` for Celery events.
"""
import sys
from datetime import datetime

from celery.app import app_or_default
from celery.utils.functional import LRUCache
from celery.utils.time import humanize_seconds

__all__ = ('Dumper', 'evdump')

TASK_NAMES = LRUCache(limit=0xFFF)

HUMAN_TYPES = {
    'worker-offline': 'shutdown',
    'worker-online': 'started',
    'worker-heartbeat': 'heartbeat',
}

CONNECTION_ERROR = """\
-> Cannot connect to %s: %s.
Trying again %s
"""


def humanize_type(type):
    try:
        return HUMAN_TYPES[type.lower()]
    except KeyError:
        return type.lower().replace('-', ' ')


class Dumper:
    """Monitor events."""

    def __init__(self, out=sys.stdout):
        self.out = out

    def say(self, msg):
        print(msg, file=self.out)
        # need to flush so that output can be piped.
        try:
            self.out.flush()
        except AttributeError:  # pragma: no cover
            pass

    def on_event(self, ev):
        timestamp = datetime.utcfromtimestamp(ev.pop('timestamp'))
        type = ev.pop('type').lower()
        hostname = ev.pop('hostname')
        if type.startswith('task-'):
            uuid = ev.pop('uuid')
            if type in ('task-received', 'task-sent'):
                task = TASK_NAMES[uuid] = '{}({}) args={} kwargs={}' \
                    .format(ev.pop('name'), uuid,
                            ev.pop('args'),
                            ev.pop('kwargs'))
            else:
                task = TASK_NAMES.get(uuid, '')
            return self.format_task_event(hostname, timestamp,
                                          type, task, ev)
        fields = ', '.join(
            f'{key}={ev[key]}' for key in sorted(ev)
        )
        sep = fields and ':' or ''
        self.say(f'{hostname} [{timestamp}] {humanize_type(type)}{sep} {fields}')

    def format_task_event(self, hostname, timestamp, type, task, event):
        fields = ', '.join(
            f'{key}={event[key]}' for key in sorted(event)
        )
        sep = fields and ':' or ''
        self.say(f'{hostname} [{timestamp}] {humanize_type(type)}{sep} {task} {fields}')


def evdump(app=None, out=sys.stdout):
    """Start event dump."""
    app = app_or_default(app)
    dumper = Dumper(out=out)
    dumper.say('-> evdump: starting capture...')
    conn = app.connection_for_read().clone()

    def _error_handler(exc, interval):
        dumper.say(CONNECTION_ERROR % (
            conn.as_uri(), exc, humanize_seconds(interval, 'in', ' ')
        ))

    while 1:
        try:
            conn.ensure_connection(_error_handler)
            recv = app.events.Receiver(conn, handlers={'*': dumper.on_event})
            recv.capture()
        except (KeyboardInterrupt, SystemExit):
            return conn and conn.close()
        except conn.connection_errors + conn.channel_errors:
            dumper.say('-> Connection lost, attempting reconnect')


if __name__ == '__main__':  # pragma: no cover
    evdump()

"""Utility to dump events to screen.

This is a simple program that dumps events to the console
as they happen.  Think of it like a `tcpdump` for Celery events.
"""
import sys
from datetime import datetime

from celery.app import app_or_default
from celery.utils.functional import LRUCache
from celery.utils.time import humanize_seconds

__all__ = ('Dumper', 'evdump')

TASK_NAMES = LRUCache(limit=0xFFF)

HUMAN_TYPES = {
    'worker-offline': 'shutdown',
    'worker-online': 'started',
    'worker-heartbeat': 'heartbeat',
}

CONNECTION_ERROR = """\
-> Cannot connect to %s: %s.
Trying again %s
"""


def humanize_type(type):
    try:
        return HUMAN_TYPES[type.lower()]
    except KeyError:
        return type.lower().replace('-', ' ')


class Dumper:
    """Monitor events."""

    def __init__(self, out=sys.stdout):
        self.out = out

    def say(self, msg):
        print(msg, file=self.out)
        # need to flush so that output can be piped.
        try:
            self.out.flush()
        except AttributeError:  # pragma: no cover
            pass

    def on_event(self, ev):
        timestamp = datetime.utcfromtimestamp(ev.pop('timestamp'))
        type = ev.pop('type').lower()
        hostname = ev.pop('hostname')
        if type.startswith('task-'):
            uuid = ev.pop('uuid')
            if type in ('task-received', 'task-sent'):
                task = TASK_NAMES[uuid] = '{}({}) args={} kwargs={}' \
                    .format(ev.pop('name'), uuid,
                            ev.pop('args'),
                            ev.pop('kwargs'))
            else:
                task = TASK_NAMES.get(uuid, '')
            return self.format_task_event(hostname, timestamp,
                                          type, task, ev)
        fields = ', '.join(
            f'{key}={ev[key]}' for key in sorted(ev)
        )
        sep = fields and ':' or ''
        self.say(f'{hostname} [{timestamp}] {humanize_type(type)}{sep} {fields}')

    def format_task_event(self, hostname, timestamp, type, task, event):
        fields = ', '.join(
            f'{key}={event[key]}' for key in sorted(event)
        )
        sep = fields and ':' or ''
        self.say(f'{hostname} [{timestamp}] {humanize_type(type)}{sep} {task} {fields}')


def evdump(app=None, out=sys.stdout):
    """Start event dump."""
    app = app_or_default(app)
    dumper = Dumper(out=out)
    dumper.say('-> evdump: starting capture...')
    conn = app.connection_for_read().clone()

    def _error_handler(exc, interval):
        dumper.say(CONNECTION_ERROR % (
            conn.as_uri(), exc, humanize_seconds(interval, 'in', ' ')
        ))

    while 1:
        try:
            conn.ensure_connection(_error_handler)
            recv = app.events.Receiver(conn, handlers={'*': dumper.on_event})
            recv.capture()
        except (KeyboardInterrupt, SystemExit):
            return conn and conn.close()
        except conn.connection_errors + conn.channel_errors:
            dumper.say('-> Connection lost, attempting reconnect')


if __name__ == '__main__':  # pragma: no cover
    evdump()
