Configuration

Pigsty treats Infra & Database as Code. You can describe the infrastructure & database clusters through a declarative interface. All your essential work is to describe your need in the inventory, then materialize it with a simple idempotent playbook.

Inventory

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

The inventory consists of two parts: global vars & multiple group definitions. You can define new clusters with inventory groups: all.children. And describe infra and set global default parameters for clusters 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 lots of config examples under files/pigsty

Cluster

Each group may represent a cluster, which could be a Node cluster, PostgreSQL cluster, Redis cluster, Etcd cluster, or Minio cluster, etc… They all use the same format: group vars & hosts. You can define cluster members with all.children.<cls>.hosts and describe cluster with cluster parameters in all.children.<cls>.vars. Here is an example of 3 nodes PostgreSQL HA cluster named pg-test:

pg-test:   # Group Name
  vars:    # Group Vars (Cluster Parameters)
    pg_cluster: pg-test
  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

You can also define parameters for a specific host, as known as host vars. It will override group vars and global vars. Which is usually used for assigning identities to nodes & database instances.

Parameter

Global vars, Group vars, and Host vars are dict objects consisting of a series of K-V pairs. Each pair is a named Parameter consisting of a string name as the key and a value of one of five types: boolean, string, number, array, or object. Check parameter reference for detailed syntax & semantics.

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.

Parameters can be specified & overridden with the following precedence.

Playbook Args  >  Host Vars  >  Group Vars  >  Global Vars  >  Defaults

For examples:

• Force removing existing databases with Playbook CLI Args -e pg_clean=true
• Override an instance role with Instance Level Parameter pg_role on Host Vars
• Override a 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, it will use the default value from role implementation (16 by default)

Reference

Pigsty have 280+ parameters, check Parameter for details.