Patroni

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Product description

Patroni is a clustering technology for PostgreSQL.

Architecture

The examples of the product components and pattern's interaction are displayed in the following tables.

Software pattern summary

The following table gives an overview of the pattern characteristics:

Product component	OS type	Versioning	Pattern depth
Patroni Cluster	Windows, UNIX	Active	Instance-based

Platforms supported by the pattern

This pattern supports the Windows and UNIX platforms.

Identification

To run a discovery of the product, the pattern must be triggered. This section describes conditions under which the pattern can be triggered.

Software instance triggers

The following table gives details about the pattern triggers:

Pattern	Trigger node	Attribute	Condition	Argument
Patroni	DiscoveredProcess	cmd	matches	regex '(?i)\bpatroni(?:\.exe)?$'
		or
		cmd	matches	regex "(?i)\bpython\d?(?:\.\d+)?(?:\.exe)?$"
		and
		args	matches	regex '\bpatroni\b'

Simple identification mappings

The following component is identified by using the simple identity mapping that maps the product's known processes:

Name	Condition
Patroni Clustering Technology	matches regex "(?i)\bpatroni(?:\.exe)?$"

Versioning

The pattern attempts to retrieve version information by running <install_root>/patronictl <yml_file> version to obtain the install_root and yml_file from the trigger process.

Application model

If the pattern discovers a SoftwareInstance of Patroni, it defines its architecture in the form of the application model.

Cluster node

The pattern creates a SoftwareCluster node with a key based on the Patroni Cluster type and instance name. The pattern retrieves the cluster instance name by running <install_root>/patronictl <yml_file> list to obtain the install_root and yml_file from the trigger process.

PostgreSQL Database

The pattern creates a SoftwareContainment link from the SoftwareCluster to all PostgreSQL Database Server SoftwareInstances running on the host with the same instance name as the cluster. The pattern retrieves the patroni_role of this PostgreSQL Database Server SoftwareInstance by running <install_root>/patronictl <yml file> list to obtain the install_root and yml_file from the trigger process.

Links to other SoftwareInstances

The pattern creates communication links from the cluster to the following SoftwareInstances. In all cases ,the cluster is the client.

SoftwareInstance type	How the pattern finds the remote host
Apache Zookeeper Server	From the yml_file, the location of which is the trigger process.
etcd
HAProxy	Always on the local host.

BMC Discovery models a typical installation of the Patroni cluster as shown in the following image:

Subject matter expertise

Inputs from subject matter experts are welcome on any other potential approaches not discussed in this topic.