UCARP

Table of Contents

1. Description
2. Usage
3. Reference
4. Limitations - OS compatibility, etc.
5. Development - Guide for contributing to the module

Description

This module configures the network interface to start up on a virtual IP, and optionally, manages installation of ucarp. Multiple ucarp instances on the same host are also supported.

It installs the ucarp package and creates a configuration file in /etc/ucarp/vip-*.conf for each ucarp instance required.

Supported/tested versions: OS: CentOS 7.x Puppet: 4.x

More about UCARP

UCARP allows a couple of hosts to share common virtual IP addresses in order to provide automatic failover. It is a portable userland implementation of the secure and patent-free Common Address Redundancy Protocol (CARP, OpenBSD’s alternative to the patents-bloated VRRP).

For more information on UCARP: https://download.pureftpd.org/ucarp/README

Usage

To get started, this example shows how to install the ucarp service and create configuration for a 2-node 'cluster'. This resource definition would be created on each node in the cluster.

  ucarp::vip { 'nginx_cluster':
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.1',
  }

By default, the master will be randomly assigned. To set a different master, override with setting master_host.

  ucarp::vip { 'nginx_cluster':
    cluster_name   => 'nginx_cluster',
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.1',
    vhid           => '001',
    master_host    => 'nginx-02.example.com',
  }

Simple definition, for 2 nodes with overrides.

  class { 'ucarp':
    manage_package    => false,
    cluster_name      => 'my_nginx_cluster',
    app_password      => 'somepassword',
    network_interface => 'eth1',
  }

  ucarp::vip { 'nginx_cluster':
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.1',
    vhid           => '001',
  }

Slightly more complex definition, for 2 nodes, with multiple ucarp instances with different vip_ip_address and vhid. If an existing vhid is entered, the configuration will be overwritten.

  ucarp::vip { 'nginx_cluster-01':
    cluster_name   => 'dev_nginx_cluster',
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.1',
    vhid           => '001',
  }

  ucarp::vip { 'nginx_cluster-02':
    cluster_name   => 'uat_nginx_cluster',
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.2',
    vhid           => '002',
  }

  ucarp::vip { 'nginx_cluster-03':
    cluster_name   => 'prod_nginx_cluster',
    cluster_nodes  => ['nginx-01.example.com','nginx-02.example.com'],
    vip_ip_address => '192.168.1.3',
    vhid           => '003',
  }

Reference

ucarp::vip

Definition to manage ucarp vip configuration files.

• ensure (property) - Defaults to present. If absent, only configuration for the specific vhid will be removed.

• cluster_name (parameter) - VIP or cluster name for use in calculating MD5 hashes, especially when multiple instances are running on a single host. Also used to generate passwords if one not specified. Defaults to $name for this resource.

• cluster_nodes (parameter) - List of hostnames (FQDN) that will utilise this ucarp configuration. Assumption is that the first node in the list is the master, unless otherwise stated. Required.

• vip_ip_address (parameter) - Virtual IP address. Required.

• vhid (parameter) - Number betwen 001 and 255, used to generate VIP configuration in /etc/ucarp/vip-<vhid>.conf. If an existing number is provided, this configuration will be overwritten. Defaults to 001.

• host_ip_address (parameter) - The real IP address of this host. Defaults to facter value for $::ipaddress.

• app_password (parameter) - VIP password. Generated if not supplied.

• master_host (parameter) - Name of the master host. Should be fqdn. If not specified, the master host will be deemed to be the first host listed in cluster_nodes. Optional.

• network_interface (parameter) - Network interface to use. Default is eth0.

Limitations

This module is compatible with Puppet versions >= 4.x, and has only been tested with CentOS versions >= 7.2.x

Development

Any contributions and updates welcome. Please create a PR with your changes, and ensure that tests and coverage have been updated/maintained with your code. Tests must pass before any PR will be accepted. Code coverage must be maintained at 100%.

Alternatively, please log an issue/feature request.