Inventory

Each pigsty deployment has a corresponding config inventory. It could be stored in a local config file in YAML format, or dynamically generated from CMDB or any ansible compatible format. Pigsty uses one monolith YAML config file by default, which is pigsty.yml, located in the pigsty home directory.

The configure script will generate the pigsty.yml file scaffold with good defaults according to your env and input, but it's OPTIONAL: you can always edit the pigsty.yml file directly as the tutorial shows.

Structure

The inventory consists of two parts: global vars & multiple groups. You can define new clusters in all.children. And describe infra with global vars: all.vars. Which may look like this:

all:                  # Top-level object: all
  vars: {...}         # Global Parameters
  children:           # Group Definitions
    infra:            # Group Definition: 'infra'
      hosts: {...}        # Group Membership: 'infra'
      vars:  {...}        # Group Parameters: 'infra'
    etcd:    {...}    # Group Definition: 'etcd'
    pg-meta: {...}    # Group Definition: 'pg-meta'
    pg-test: {...}    # Group Definition: 'pg-test'
    redis-test: {...} # Group Definition: 'redis-test'
    # ...

There are plenty of examples under conf/, which can also be used as templates during configure.

Cluster

Each ansible group may represent a cluster, which could be a Node cluster, PostgreSQL cluster, Redis cluster, Etcd cluster, or Minio cluster, etc…

Cluster definition consists of two parts: hosts & vars. You can define cluster members in <cls>.hosts and describe cluster with parameters in <cls>.vars. Here's an example of a 3-node HA PG cluster:

all:
  children:    # All Groups
    pg-test:   # Group Name
      hosts:   # Group Host (Cluster Membership)
        10.10.10.11: { pg_seq: 1, pg_role: primary } # Host1
        10.10.10.12: { pg_seq: 2, pg_role: replica } # Host2
        10.10.10.13: { pg_seq: 3, pg_role: offline } # Host3
      vars:    # Group Vars (Cluster Parameters)
        pg_cluster: pg-test

The vars in cluster level will override the global vars, and vars in host level will override the cluster vars and global vars.

Parameter

Parameters are key-value pairs that define all entities in the deployment. The key is a string name, and the value can be one of five types: boolean, string, number, array, or object.

And parameters can be set at different levels with the following precedence:

Here are some examples about parameter precedence:

• Force removing existing databases with Playbook CLI Args -e pg_clean=true
• Override pg instance role with Instance Level Parameter pg_role on Host Vars
• Override pg cluster name with Cluster Level Parameter pg_cluster on Group Vars.
• Specify global NTP servers with Global Parameter node_ntp_servers on Global Vars
• If no pg_version is set, pigsty will use the default value from role implementation (17 by default)

Every parameter has a proper default value except for mandatory IDENTITY PARAMETERS; they are used as identifiers and must be set explicitly. Such as pg_cluster, pg_role, and pg_seq in above snippet.

Available parameters vary according to the modules:

Reference

Pigsty have 280+ parameters, check module parameters for details.