Rejected is a AMQP consumer daemon and message processing framework. It allows for rapid development of message processing consumers by handling all of the core functionality of communicating with RabbitMQ and management of consumer processes.
Rejected runs as a master process with multiple consumer configurations that are each run it an isolated process. It has the ability to collect statistical data from the consumer processes and report on it.
- Automatic exception handling including connection management and consumer restarting
- Smart consumer classes that can automatically decode and deserialize message bodies based upon message headers
- Metrics logging and submission to statsd
- Built-in profiling of consumer code
- Ability to write asynchronous code in consumers allowing for parallel communication with external resources
https://rejected.readthedocs.org
from rejected import consumer
import logging
LOGGER = logging.getLogger(__name__)
class Test(consumer.Consumer):
def process(self, message):
LOGGER.debug('In Test.process: %s' % message.body)
To make a consumer async, you can decorate the Consumer.prepare and Consumer.process methods using Tornado's @gen.coroutine. Asynchronous consumers to handle multiple messages in the same process, but rather allow you to use asynchronous clients like Tornado's AsyncHTTPClient and the Queries PostgreSQL library to perform parallel tasks using coroutines.
import logging
from rejected import consumer
from tornado import gen
from tornado import httpclient
class AsyncExampleConsumer(consumer.Consumer):
@gen.coroutine
def process(self):
LOGGER.debug('Message: %r', self.body)
http_client = httpclient.AsyncHTTPClient()
results = yield [http_client.fetch('http://www.github.com'),
http_client.fetch('http://www.reddit.com')]
LOGGER.info('Length: %r', [len(r.body) for r in results])
%YAML 1.2
---
Application:
poll_interval: 10.0
log_stats: True
statsd:
enabled: True
host: localhost
port: 8125
prefix: applications.rejected
Connections:
rabbitmq:
host: localhost
port: 5672
user: guest
pass: guest
ssl: False
vhost: /
heartbeat_interval: 300
Consumers:
example:
consumer: rejected.example.Consumer
connections: [rabbitmq]
qty: 2
queue: generated_messages
qos_prefetch: 100
ack: True
max_errors: 100
config:
foo: True
bar: baz
Daemon:
user: rejected
group: daemon
pidfile: /var/run/rejected/example.%(pid)s.pid
Logging:
version: 1
formatters:
verbose:
format: "%(levelname) -10s %(asctime)s %(process)-6d %(processName) -25s %(name) -20s %(funcName) -25s: %(message)s"
datefmt: "%Y-%m-%d %H:%M:%S"
verbose_correlation:
format: "%(levelname) -10s %(asctime)s %(process)-6d %(processName) -25s %(name) -20s %(funcName) -25s: %(message)s {CID %(correlation_id)s}"
datefmt: "%Y-%m-%d %H:%M:%S"
syslog:
format: "%(levelname)s <PID %(process)d:%(processName)s> %(name)s.%(funcName)s: %(message)s"
syslog_correlation:
format: "%(levelname)s <PID %(process)d:%(processName)s> %(name)s.%(funcName)s: %(message)s {CID %(correlation_id)s)"
filters:
correlation:
'()': rejected.log.CorrelationFilter
'exists': True
no_correlation:
'()': rejected.log.CorrelationFilter
'exists': False
handlers:
console:
class: logging.StreamHandler
formatter: verbose
debug_only: false
filters: [no_correlation]
console_correlation:
class: logging.StreamHandler
formatter: verbose_correlation
debug_only: false
filters: [correlation]
syslog:
class: logging.handlers.SysLogHandler
facility: daemon
address: /var/run/syslog
formatter: syslog
filters: [no_correlation]
syslog_correlation:
class: logging.handlers.SysLogHandler
facility: daemon
address: /var/run/syslog
formatter: syslog
filters: [correlation]
loggers:
helper:
level: INFO
propagate: true
handlers: [console, console_correlation, syslog, syslog_correlation]
rejected:
level: INFO
propagate: true
handlers: [console, console_correlation, syslog, syslog_correlation]
tornado:
level: INFO
propagate: true
handlers: [console, console_correlation, syslog, syslog_correlation]
disable_existing_loggers: true
incremental: false
Available at https://rejected.readthedocs.org/en/latest/history.html