A PgQ to RabbitMQ relay. Mikkoo is a PgQ consumer that that publishes to RabbitMQ. In addition, it includes a built in auditing system that can be used to confirm that all PgQ events are received by RabbitMQ.

Mikkoo is named for the rabbit in the "Clever Rabbit and the Elephant" fable.

Mikkoo is available on the Python Package Index and can be installed via pip:

pip install mikkoo

Once you've setup Skytools you may want to install the optional included utility functions in mikkoo.sql to make usage easier.

You can do this with a combination of curl and psql:

curl -L https://github.com/gmr/mikkoo/blob/master/mikkoo.sql | psql

This will install multiple stored procedures and an audit table in a mikkoo schema. Take a look at the DDL to get a good idea of what each funciton is and how it can be used.

1. Install pgq into your database and create the queue:

   # CREATE EXTENSION pgq;
   CREATE EXTENSION
   # SELECT pgq.create_queue('test');
   create_queue
   --------------
               1
   (1 row)

2. Ensure that pgqd is running.

When inserting events into a PgQ queue, the pgq.insert_event/7 function should be used with the following field mappings:

There is a convenience schema in the mikkoo.sql file that adds stored procedures for creating properly formatted mikkoo events in PgQ. In addition, there is are auditing functions that allow for the creation of an audit-log of events that were sent to PgQ.

The following table defines the available fields that can be set in a JSON blob in the ev_extra3 field when inserting an event.

Values assigned in the JSON blob provided to ev_extra3 take precedence over the automatically assigned app_id, content_type, correlation_id, headers, and timestamp values created by Mikkoo at processing time.

As of 1.0, Mikkoo will automatically add four AMQP headers property values. These values will not overwrite any values with the same name specified in ev_extra4. overwriting values with the same name, even if they are specified in the The sequence value is a dynamically generated ID that attempts to provide fuzzy distributed ordering information. The timestamp value is the ISO-8601 representation of the ev_time field, which is created when an event is added to PgQ. The txid value is the ev_txid value, the PgQ transaction ID for the event. These values are added to help provide some level of deterministic ordering. The origin value is the hostname of the server that Mikkoo is running on.

The following example inserts a JSON blob message body of {"foo": "bar"} that will be published to the postgres exchange in RabbitMQ using the test.routing-key routing key. The content type is specified in ev_extra2 and the AMQP type message property is specified in ev_extra3.

# SELECT pgq.insert_event('test', 'test.routing-key', '{"foo": "bar"}', 'postgres', 'application/json', '{"type": "example"}', '');
 insert_event
--------------
            4
(1 row)

When this message is received by RabbitMQ it will have a message body of:

{"foo": "bar"}

And it will have message properties similar to the following:

The Mikkoo configuration file uses YAML for markup and allows for one or more PgQ queue to be processed.

If you have a Sentry or a Sentry account, the Application/sentry_dsn setting will turn on sentry exception logging, if the raven client library is installed.

Queues are configured by name under the Application/workers stanza. The following example configures two workers for the processing of a queue named invoices. Each worker process connects to a local PostgreSQL and RabbitMQ instance using default credentials.

Application:
  workers:
     invoices:
       postgres_url: postgresql://localhost:5432/postgres
       rabbitmq_url: amqp://localhost:5672/%2f
       confirm: False

The following table details the configuration options available per queue:

The following is an example of a full configuration file:

Application:

  poll_interval: 10
  sentry_dsn: [YOUR SENTRY DSN]

  statsd:
    enabled: true
    host: localhost
    port: 8125

  workers:
    test:
      confirm: False
      consumer_name: my_consumer
      max_failures: 5
      postgres_url: postgresql://localhost:5432/postgres
      rabbitmq_url: amqp://localhost:5672/%2f
      retry_delay: 5
      unregister: False
      wait_duration: 5

Daemon:
  user: mikkoo
  pidfile: /var/run/mikkoo

Logging:
  version: 1
  formatters:
    verbose:
      format: '%(levelname) -10s %(asctime)s  %(process)-6d %(processName) -20s %(name) -18s: %(message)s'
      datefmt: '%Y-%m-%d %H:%M:%S'
  handlers:
    console:
      class: logging.StreamHandler
      formatter: verbose
      debug_only: True
  loggers:
    helper:
      handlers: [console]
      level: INFO
      propagate: true
    mikkoo:
      handlers: [console]
      level: INFO
      propagate: true
    pika:
      handlers: [console]
      level: ERROR
      propagate: true
    queries:
      handlers: [console]
      level: ERROR
      propagate: true
    tornado:
      handlers: [console]
      level: ERROR
      propagate: true
  root:
    handlers: [console]
    level: CRITICAL
    propagate: true
  disable_existing_loggers: true
  incremental: false

After creating a configuration file for Mikkoo like the one above, simply run the mikkoo application providing the path to the configuration file:

mikkoo -c mikkoo.yml

The application will attempt to daemonize unless you use the -f foreground CLI switch.

Mikkoo's CLI help can be invoked with --help and yields the following output:

$ mikkoo -h
usage: mikkoo [-h] [-c CONFIG] [-f]

Mikkoo is a PgQ to RabbitMQ Relay

optional arguments:
  -h, --help            show this help message and exit
  -c CONFIG, --config CONFIG
                        Path to the configuration file
  -f, --foreground      Run the application interactively