Selective VAG Calculation on Configuration Server Proxies

Overview

This feature extends Local VAG calculation on selected Configuration Server Proxies. It allows to limit the set of VAGs, calculated by a VAG-calculating proxy (that is, a proxy configured with force-vag-calculation=true), to a configured subset.

Feature configuration

• The feature configuration is based on a notion of "VAG cluster". VAG cluster is a named group of VAGs.
• Each VAG-calculating proxy can be configured to calculate only VAGs assigned to one or more clusters.
• Each VAG can be assigned to one or more clusters explicitly or through its containing folder.

Proxy configuration

To limit a proxy to calculate only VAGs of specific cluster: in the proxy's Application Options create section named vag-clusters, add the option with the cluster name and value true.

Additional clusters may be added in a similar way. For example:

In the proxy's Application object Options:

[vag-clusters]
A=true
B=true

Here, A and B are the names of the two clusters. Cluster names are arbitrary ascii strings that are no longer than 64 characters. They avoid blanks or unprintable characters.

A proxy configured this way will calculate only VAGs assigned to clusters A or B. All other VAGs defined in the configuration will not be calculated and exposed as empty.

In a load-balanced proxy configuration (when the proxy-cluster-name option is specified in the proxy options), the vag-clusters section must be specified in the common Application object, indicated by the proxy-cluster-name option. If the common Application object contains the vag-clusters section, the proxy's own Application object's section is ignored.

Changes to the proxy's vag-clusters section take effect after proxy restart or complete data reload.

VAGs configuration

To assign a VAG to a cluster:

In the VAG's Agent Group object create section named vag-clusters, add the option with the cluster name and value true.

Additional clusters may be added in a similar way, making the VAG assigned to more than one cluster. For xxample:

In the VAG's Agent Group object Annex:

[vag-clusters]
A=true
B=true

This way, the VAG will be assigned to clusters A and B. It will be calculated by the proxies configured to calculate either A or B.

Alternatively, same entries can be created in the Agent Groups Folder Object Annex. This will apply the settings to all VAGs directly contained in the folder and not in the subfolders.

If both VAG and its containing folder are configured with the vag-clusters section, the VAG's settings prevail.

To streamline maintenance, it is recommended to keep VAG cluster membership at the folder level, as opposed to assigning it to individual VAGs.

Changes to the VAG and Folder vag-clusters sections take effect immediately. Corresponding proxies immediately start/stop VAG calculation according to applied changes.

If an existing VAG, having no own vag-clusters section, is moved between folders, new parent's settings apply immediately.

If a new VAG is created, its own and/or parent folder settings apply immediately.

When a VAG goes out of a proxy's calculation scope due to effective change in its vag-clusters section (direct or through containing folder), the proxy reports its content es emptied.

When a VAG goes into a proxy's calculation scope, the proxy starts VAG calculation for this VAG and reports all member agents as added to the VAG.

These operations are intended to maintain consistency to a VAG membership through a proxy restart.

Important

• Such operations, similarly to a VAG script change, are calculation-heavy on both the proxy and subscribed clients.
• All names, including cluster names, are case-sensitive.
• In all object options in the vag-cluster sections with values other than true are ignored with one exception: in a VAG object option with the value false cancels corresponding value in the containing folder.
• A VAG can be set to true only once in the section vag-clusters.