Congress Introduction and Installation

1. What is Congress

Congress is an open policy framework for the cloud. With Congress, a cloud operator can declare, monitor, enforce, and audit “policy” in a heterogeneous cloud environment. Congress get inputs from a cloud’s various cloud services; for example in Openstack, Congress fetches information about VMs from Nova, and network state from Neutron, etc. Congress then feeds input data from those services into its policy engine where Congress verifies that the cloud’s actual state abides by the cloud operator’s policies. Congress is designed to work with any policy and any cloud service.

2. Why is Policy Important

The cloud is a collection of autonomous services that constantly change the state of the cloud, and it can be challenging for the cloud operator to know whether the cloud is even configured correctly. For example,

  • The services are often independent from each other, and do not support transactional consistency across services, so a cloud management system can change one service (create a VM) without also making a necessary change to another service (attach the VM to a network). This can lead to incorrect behavior.
  • Other times, we have seen a cloud operator allocate cloud resources and then forget to clean them up when the resources are no longer in use, effectively leaving garbage around the system and wasting resources.
  • The desired cloud state can also change over time. For example, if a security vulnerability appears in Linux version X, then all machines with version X that were ok in the past are now in an undesirable state. A version number policy would detect all the machines in that undesirable state. This is a trivial example, but the more complex the policy, the more helpful a policy system becomes.

Congress’s job is to help people manage that plethora of state across all cloud services with a susinct policy language.

3. Using Congress

Setting up Congress involves writing policies and configuring Congress to fetch input data from the cloud services. The cloud operator writes policy in the Congress policy language, which receives input from the cloud services in the form of tables. The language itself resembles datalog. For more detail about the policy language and data format see Policy.

To add a service as an input data source, the cloud operator configures a Congress “driver”, and the driver queries the service. Congress already has drivers for several types of service, but if a cloud operator needs to use an unsupported service, she can write a new driver without much effort, and probably contribute the driver to the Congress project so that no one else needs to write the same driver.

Finally, when using Congress, the cloud operator must choose what Congress should do with the policy it has been given:

  • monitoring: detect violations of policy and provide a list of those violations
  • proactive enforcement: prevent violations before they happen (functionality that requires other services to consult with Congress before making changes)
  • reactive enforcement: correct violations after they happen (a manual process that Congress tries to simplify)

In the future, Congress will also help the cloud operator audit policy (analyze the history of policy and policy violations).

Congress is free software and is licensed with Apache.

  • Free software: Apache license

4. Installing Congress

There are 2 ways to install Congress.

  • As part of devstack. Get Congress running alongside other OpenStack services like Nova and Neutron, all on a single machine. This is a great way to try out Congress for the first time.
  • Standalone. Get Congress running all by itself. Congress works well with other OpenStack services but can be deployed without them.

4.1 Devstack-install

The contrib/devstack/ directory contains the files necessary to integrate Congress with devstack.

To install, make sure you have git installed. Then:

$ git clone
 (Or set env variable DEVSTACKDIR to the location to your devstack code)

$ wget

$ chmod u+x

$ ./

Configure ENABLED_SERVICES in the devstack/localrc file (make sure to include congress):


Run devstack as normal. Note: the default data source configuration assumes the admin password is ‘password’:

$ ./

4.2 Standalone-install

Install the following software, if you haven’t already.

Clone Congress:

$ git clone
$ cd congress

Install Source code:

$ sudo python install

Configure congress:

(Assume you put config files in /etc/congress)

$ sudo mkdir -p /etc/congress
$ sudo mkdir -p /etc/congress/snapshot
$ sudo cp etc/api-paste.ini /etc/congress
$ sudo cp etc/policy.json /etc/congress
$ sudo cp etc/congress.conf.sample /etc/congress/congress.conf

Uncomment policy_path and add drivers in /etc/congress/congress.conf [DEFAULT] section:

drivers = congress.datasources.neutronv2_driver.NeutronV2Driver,congress.datasources.glancev2_driver.GlanceV2Driver,congress.datasources.nova_driver.NovaDriver,congress.datasources.keystone_driver.KeystoneDriver,congress.datasources.ceilometer_driver.CeilometerDriver,congress.datasources.cinder_driver.CinderDriver,congress.datasources.swift_driver.SwiftDriver,congress.datasources.plexxi_driver.PlexxiDriver,congress.datasources.vCenter_driver.VCenterDriver,congress.datasources.cloudfoundryv2_driver.CloudFoundryV2Driver,congress.datasources.murano_driver.MuranoDriver,congress.datasources.ironic_driver.IronicDriver

Modify [keystone_authtoken] and [database] according to your environment.

For setting congress with "noauth":
  Add the following line to [DEFAULT] section in /etc/congress/congress.conf

  auth_strategy = noauth

  Also, might want to delete/comment [keystone_authtoken] section in

Create database:

$ mysql -u root -p
$ mysql> CREATE DATABASE congress;
$ mysql> GRANT ALL PRIVILEGES ON congress.* TO 'congress'@'localhost' \
$ mysql> GRANT ALL PRIVILEGES ON congress.* TO 'congress'@'%' \

(Configure congress.conf with db information)

Push down schema
$ sudo congress-db-manage --config-file /etc/congress/congress.conf upgrade head

Setup congress accounts:

(You should change parameters according to your environment)

$ ADMIN_ROLE=$(openstack role list | awk "/ admin / { print \$2 }")
$ SERVICE_TENANT=$(openstack project list | awk "/ admin / { print \$2 }")
$ CONGRESS_USER=$(openstack user create --password password --project admin \
  --email "" congress)
$ openstack role add $ADMIN_ROLE --user $CONGRESS_USER --project \
$ CONGRESS_SERVICE=$(openstack service create congress --type "policy" \
  --description "Congress Service")
$ openstack endpoint create $CONGRESS_SERVICE \
  --region RegionOne \
  --publicurl \
  --adminurl \

Configure datasource drivers:

First make sure you have congress client (project python-congressclient) installed.
Run this command for every service that congress will poll for data:

$ openstack congress datasource create $SERVICE "$SERVICE" \
  --config username=$OS_USERNAME \
  --config tenant_name=$OS_TENANT_NAME \
  --config password=$OS_PASSWORD \
  --config auth_url=http://$SERVICE_HOST:5000/v2.0

Please note that the service name $SERVICE should match the id of the datasource driver,
e.g. "neutronv2" for Neutron and "glancev2" for Glance. $OS_USERNAME, $OS_TENANT_NAME,
$OS_PASSWORD and $SERVICE_HOST are used to configure the related datasource driver
so that congress knows how to talk with the service.

Start congress:

$ sudo /usr/local/bin/congress-server --debug

Install test harness:

$ pip install 'tox<1.7'

Run unit tests:

$ tox -epy27

Read the HTML documentation:

$ make docs
Open doc/html/index.html in a browser