Concept

Node is an abstraction of hardware resources, which can be bare metal, virtual machines, or even k8s pods.

There are different types of nodes in Pigsty:

• Common nodes, nodes that managed by Pigsty
• Admin node, the node where pigsty is installed and issue admin commands
• Infra node, the node where the INFRA module is installed

The admin node is usually overlapped with the infra node, if there’s more than one infra node, the first one is often used as the default admin node, and the rest of the infra nodes can be used as backup admin nodes.

Common Node

You can manage nodes with Pigsty, and install modules on them. The node.yml playbook will adjust the node to desired state.

Some services will be added to all nodes by default:

Docker & Keepalived are optional components, enabled when required.

ADMIN Node

There is one and only one admin node in a pigsty deployment, which is specified by admin_ip. It is set to the local primary IP during configure.

The node will have ssh / sudo access to all other nodes, which is critical; ensure it’s fully secured.

INFRA Node

A pigsty deployment may have one or more infra nodes, usually 2 ~ 3, in a large production environment.

The infra group specifies infra nodes in the inventory. And infra nodes will have INFRA module installed (DNS, Nginx, Prometheus, Grafana, etc…),

The admin node is also the default and first infra node, and infra nodes can be used as ‘backup’ admin nodes.

PGSQL Node

The node with PGSQL module installed is called a PGSQL node. The node and pg instance is 1:1 deployed. And node instance can be borrowed from corresponding pg instances with node_id_from_pg.