Architecture

A "node" refers to a resource that is SSH accessible and offers a bare Linux OS environment. It could be a physical machine, a virtual machine, or an OS-like container equipped with systemd, sudo and sshd.

There are three different types of nodes in Pigsty, In a one-node deployment, they are the same one.

Example

In the following 4-node sandbox config snippet, we have 4 common nodes.
And the 10.10.10.10 is marked as Infra Node and Admin Node simultaneously.

all:
  children:
    infra:   { hosts: { 10.10.10.10: { infra_seq: 1 } } }  # <--- mark this as infra node
    etcd:    { hosts: { 10.10.10.10: { etcd_seq: 1 } }, vars: { etcd_cluster: etcd } }
    pg-meta: { hosts: { 10.10.10.10: { pg_seq: 1, pg_role: primary } }, vars: { pg_cluster: pg-meta } }
    pg-test:
      hosts:
        10.10.10.11: { pg_seq: 1, pg_role: primary }
        10.10.10.12: { pg_seq: 2, pg_role: replica }
        10.10.10.13: { pg_seq: 3, pg_role: replica }
      vars: { pg_cluster: pg-test }
  vars:
    admin_ip: 10.10.10.10    # <--- mark this as admin node

Common Node

Common nodes have the following components enabled by default in Pigsty:

These components are optional, can be enabled with parameters.

ADMIN Node

Admin Node is the first node where Pigsty is installed, all control commands are issued from it.

There is one and only one admin node in a pigsty deployment, which is specified by admin_ip. This parameter will be set during the configure procedure, to the value of primary IP address.

INFRA Node

A pigsty deployment may have one or more infra nodes, at least 1, 2 or more for production deployment.

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

PGSQL Node

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

Here are additional components & service port on PGSQL nodes: