NetScaler Application Delivery Controller Plugin Manual

Preface

This document describes the functionality provided by the Citrix NetScaler Application Delivery Controller (netscaler) plugin.

Refer to XL Deploy Reference Manual for background information on XL Deploy and deployment concepts.

Overview

The NetScaler plugin is a XL Deploy plugin that adds capability for managing deployments done to application and web servers whose traffic is managed by a NetScaler loadbalancing device.

See the Features section below for details.

Features

Allows servers / services to be taken out of the load balancing pool before a deployment and put back after the deployment has been performed.

Requirements

XL Deploy requirements
- XL Deploy: version 4.5.0+
- NetScaler: 8.1, 9.x and 10.x
- Other XL Deploy Plugins:
  - loadbalancer-plugin (Distributed together)
  - group-orchestrator-plugin 4.5.0+
  - webserver-plugin 4.5.0+

Functionality

The plugin supports two modes of working:

Service group based
Server/Service based

Furthermore the plugin works in conjunction with the "group-based" orchestrator to disable and enable containers which are part of a single deployment group in one go.

The group-based orchestrator will divvy up the deployment into multiple phases, based on the 'deploymentGroup' property of the containers that are being targeted. Each of these group will be disabled in the NetScaler just before they're deployed to, and will be re-enabled right after the deployment to that group. This will ensure that there is no downtime during the deployment.

Service Group based

The plugin will add the following 4 properties to every deployable and deployed to control which service in which service group this deployed affects.

		netscalerServiceGroup : STRING
		The name of the service group that the service running on the targeted container is registered under. (default: {{NETSCALER_SERVICE_GROUP}}
		netscalerServiceGroupName : STRING
		The name of the service in the service group. (default: {{NETSCALER_SERVICE_GROUP_NAME}})
		netscalerServiceGroupPort : STRING
		The port the service in the service group runs on. Note: This is a string on the deployable to support placeholder replacement. (default: {{NETSCALER_SERVICE_GROUP_PORT}})

Server/Service based

The plugin will add the following 3 properties to every container to control how the server is known in the NetScaler ADC, and how long it should take to do a graceful disable of the server:

		netscalerAddress : STRING
		The IP address or name this server is registered under in the NetScaler load balancer
		netscalerType : STRING
		Whether this is a 'server' or a 'service' in the NetScaler load balancer (default: server)
		netscalerShutdownDelay : INTEGER
		The amount of seconds before the server is disabled in the NetScaler load balancer. A value of -1 triggers use of the defaultShutdownDelay of the NetScaler device. (default: -1)

Behavior

The plugin will add three steps to the deployment of each deployment group.

A disable server step, this will stop the traffic to the servers that are managed by the loadbalancer.
A wait step, this will wait the maximum shutdown delay
An enable server step, this will start the traffic to the servers that were previously disabled.

Setting up a loadbalancing configuration

In order to setup XL Deploy to use your NetScaler ADC device, you will need to take the following steps.

Create a NetScaler (netscaler.NetScaler) configuration item in the 'Infrastructure' tree under a host, and add it as a member to the udm.Environment. The host configuration item indicates how to connect to the NetScaler device.
Add all the containers that the NetScaler device manages to the managedServers collection of the created NetScaler configuration item.

Service Group based

For the service group based setup, you can create dictionaries restricted to containers in the environment. Each of these dictionaries will need to contain the following keys:

NETSCALER_SERVICE_GROUP
NETSCALER_SERVICE_GROUP_NAME
NETSCALER_SERVICE_GROUP_PORT

As a second option, you could immediately do an initial deployment and set the values correctly on all the deployeds. During an upgrade deployment these values will be copied from the previous deployment.

Server/Service based

Configure the netscalerAddress property of each of the containers so that the NetScaler configuration item knows how the container is known within the NetScaler ADC device.

Once that is done, during any deployment to the Environment, the netscaler-plugin will ensure that the loadbalancing logic is implemented.

Loadbalancing a mixed Application Server and Web Server environment

If you have an Apache httpd server which fronts a website backed by one or more application servers, it is possible to setup a more complex loadbalancing scenario, thus ensuring that the served website is not broken during the deployment. For this, the www.ApacheHttpdServer configuration item from the standard webserver-plugin is augmented with a property called applicationServers.

Whenever a deployment is done to one or more of the containers mentioned in the applicationServers residing in the same Environment as the web server, the following happens in addition to the standard behavior:

Just before the first application server will be deployed to, the webserver will be removed from the loadbalancing configuration.
After the last application server linked to the web server has been deployed to, the webserver is put back into the loadbalancing configuration

Customization

Disable/Enable server scripts

The disable and enable server scripts, by default called:

netscaler/disable-server.cli.ftl
netscaler/enable-server.cli.ftl

contain the NetScaler CLI commands to influence the loadbalancing. They are FreeMarker templates which have access to the following variables during resolution:

servers: A list of NetScalerItem (Either ServiceGroup or ServerOrService) that are to be enabled/disabled.
loadBalancer: The netscaler.NetScaler loadbalancer that manages the servers.

Release notes

NetScaler plugin 4.5.0

XL Deploy 4.5.0 compatibility.

NetScaler plugin 4.0.0

XL Deploy 4.0.0 compatibility.

CI Reference

Configuration Item Overview

Containers

CI	Description
lb.LoadBalancer	The Load Balancer super type
netscaler.NetScaler	A Citrix NetScaler LoadBalancer

Other Configuration Items

CI	Description
lb.LoadBalancer	The Load Balancer super type
netscaler.NetScaler	A Citrix NetScaler LoadBalancer
netscaler.NetScalerParameters	Default implementation of a CI that provides ID, name and type information
netscaler.NetScalerScriptParameters	Default implementation of a CI that provides ID, name and type information

Configuration Item Details

lb.LoadBalancer

Virtual Type
Type Hierarchy	udm.BaseContainer >> udm.BaseConfigurationItem
Interfaces	udm.Taggable, udm.ConfigurationItem, udm.Container, overthere.HostContainer

The Load Balancer super type.

		Public Properties
		managedServers : SET_OF_CI<udm.Container>
		The servers managed by this load balancer

		Hidden Properties
		disableInLoadBalancer : BOOLEAN
		Whether this server should be disabled in the load balancer when it is being deployed to
		netscalerAddress : STRING
		The IP address or name this server is registered under in the NetScaler load balancer
		netscalerShutdownDelay : INTEGER
		The amount of seconds before the server is disabled in the NetScaler load balancer (A value of -1 triggers use of the defaultShutdownDelay of the NetScaler device)
		netscalerType : STRING = server
		Whether this is a 'server' or a 'service' in the NetScaler load balancer
		tags : SET_OF_STRING
		If set, only deployables with the same tag will be automatically mapped to this container.

netscaler.NetScaler

Type Hierarchy	lb.LoadBalancer >> udm.BaseContainer >> udm.BaseConfigurationItem
Interfaces	udm.Taggable, udm.ConfigurationItem, udm.Container, overthere.HostContainer

A Citrix NetScaler LoadBalancer

		Parent
		host : CI<overthere.Host>
		Host

		Public Properties
		defaultShutdownDelay : INTEGER = 0
		The amount of seconds to wait before the servers are disabled in the load balancer
		managedServers : SET_OF_CI<udm.Container>
		The servers managed by this load balancer

		Hidden Properties
		disableServersOrder : INTEGER = 8
		Disable Servers Order
		disableServersScript : STRING = netscaler/disable-server.cli.ftl
		Disable Servers Script
		enableServersOrder : INTEGER = 94
		Enable Servers Order
		enableServersScript : STRING = netscaler/enable-server.cli.ftl
		Enable Servers Script
		runScript : STRING = netscaler/run-script.cli.ftl
		Run Script
		sourceCommand : STRING = source
		Source Command
		disableInLoadBalancer : BOOLEAN
		Whether this server should be disabled in the load balancer when it is being deployed to
		netscalerAddress : STRING
		The IP address or name this server is registered under in the NetScaler load balancer
		netscalerShutdownDelay : INTEGER
		The amount of seconds before the server is disabled in the NetScaler load balancer (A value of -1 triggers use of the defaultShutdownDelay of the NetScaler device)
		netscalerType : STRING = server
		Whether this is a 'server' or a 'service' in the NetScaler load balancer
		tags : SET_OF_STRING
		If set, only deployables with the same tag will be automatically mapped to this container.

Control task	Parameter CI	Description
disableService	netscaler.NetScalerParameters	no description
enableService	netscaler.NetScalerParameters	no description
runScript	netscaler.NetScalerScriptParameters	no description

netscaler.NetScalerParameters

Type Hierarchy	udm.Parameters >> udm.BaseConfigurationItem
Interfaces	udm.ConfigurationItem

Default implementation of a CI that provides ID, name and type information.

		Public Properties
		serviceGroup : STRING
		NetScaler service group
		serviceGroupName : STRING
		NetScaler service name
		serviceGroupPort : INTEGER
		NetScaler service port

netscaler.NetScalerScriptParameters

Type Hierarchy	udm.Parameters >> udm.BaseConfigurationItem
Interfaces	udm.ConfigurationItem

Default implementation of a CI that provides ID, name and type information.

		Public Properties
		netScalerScript : STRING
		Script to execute on the NetScaler device