Congress has two modes for deployment: single-process and multi-process. If you are interested in test-driving Congress or are not concerned about high-availability, the single-process deployment is best because it is easiest to set up. If you are interested in making Congress highly-available you want the multi-process deployment.

In the single-process version, you run Congress as a single operating-system process on one node (i.e. container, VM, physical machine).

In the multi-process version, you start with the 3 components of Congress (the API, the policy engine, and the datasource drivers). You choose how many copies of each component you want to run, how you want to distribute those components across processes, and how you want to distribute those processes across nodes.

Section Configuration Options describes the common configuration options for both single-process and multi-process deployments. After that HA Overview and HA Deployment describe how to set up the multi-process deployment.

Configuration Options

In this section we highlight the configuration options that are specific to Congress. To generate a sample configuration file that lists all available options, along with descriptions, run the following commands:

$ cd /path/to/congress
$ tox -egenconfig

The tox command will create the file etc/congress.conf.sample, which has a comprehensive list of options. All options have default values, which means that even if you specify no options Congress will run.

The options most important to Congress are described below, all of which appear under the [DEFAULT] section of the configuration file.

The list of permitted datasource drivers. Default is the empty list. The list is a comma separated list of Python class paths. For example: drivers = congress.datasources.neutronv2_driver.NeutronV2Driver,congress.datasources.glancev2_driver.GlanceV2Driver
The number of seconds to wait between synchronizing datasource config from the database. Default is 0.
Whether or not congress will execute actions. If false, Congress will never execute any actions to do manual reactive enforcement, even if there are policy statements that say actions should be executed and the conditions of those actions become true. Default is True.

One of Congress’s new experimental features is distributing its services across multiple services and even hosts. Here are the options for using that feature.

Unique ID of DSE bus. Can be any string. Defaults to ‘bus’. ID should be same across all the processes of a single congress instance and should be unique across different congress instances. Used if you want to create multiple, distributed instances of Congress and can be ignored if only one congress instance is deployed as single process in rabbitMQ cluster. Appears in the [dse] section.

Here are the most often-used, but standard OpenStack options. These are specified in the [DEFAULT] section of the configuration file.

Method for authenticating Congress users. Can be assigned to either ‘keystone’ meaning that the user must provide Keystone credentials or to ‘noauth’ meaning that no authentication is required. Default is ‘keystone’.
Controls whether the INFO-level of logging is enabled. If false, logging level will be set to WARNING. Default is true. Deprecated.
Whether or not the DEBUG-level of logging is enabled. Default is false.
URL to the shared messaging service. It is not needed in a single-process Congress deployment, but must be specified in a multi-process Congress deployment.
transport_url = rabbit://<rabbit-userid>:<rabbit-password>@<rabbit-host-address>:<port>
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