Inventory

Every Pigsty deployment corresponds to an Inventory that describes key properties of the infrastructure and database clusters.

Configuration File

Pigsty uses Ansible YAML configuration format by default, with a single YAML configuration file pigsty.yml as the inventory.

~/pigsty
  ^---- pigsty.yml   # <---- Default configuration file

You can directly edit this configuration file to customize your deployment, or use the configure wizard script provided by Pigsty to automatically generate an appropriate configuration file.

Configuration Structure

The inventory uses standard Ansible YAML configuration format, consisting of two parts: global parameters (all.vars) and multiple groups (all.children).

You can define new clusters in all.children and describe the infrastructure using global variables: all.vars, which looks like this:

all:                  # Top-level object: all
  vars: {...}         # Global parameters
  children:           # Group definitions
    infra:            # Group definition: 'infra'
      hosts: {...}        # Group members: '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'
    # ...

Cluster Definition

Each Ansible group may represent a cluster, which can be a node cluster, PostgreSQL cluster, Redis cluster, Etcd cluster, Silo cluster, etc.

A cluster definition consists of two parts: cluster members (hosts) and cluster parameters (vars). You can define cluster members in <cls>.hosts and describe the cluster using configuration parameters in <cls>.vars. Here’s an example of a 3-node high-availability PostgreSQL cluster definition:

all:
  children:    # Ansible group list
    pg-test:   # Ansible group name
      hosts:   # Ansible group instances (cluster members)
        10.10.10.11: { pg_seq: 1, pg_role: primary } # Host 1
        10.10.10.12: { pg_seq: 2, pg_role: replica } # Host 2
        10.10.10.13: { pg_seq: 3, pg_role: offline } # Host 3
      vars:    # Ansible group variables (cluster parameters)
        pg_cluster: pg-test

Cluster-level vars (cluster parameters) override global parameters, and instance-level vars override both cluster parameters and global parameters.

Splitting Configuration

If your deployment is large or you want to better organize configuration files, you can split the inventory into multiple files for easier management and maintenance.

inventory/
├── hosts.yml              # Host and cluster definitions
├── group_vars/
│   ├── all.yml            # Global default variables (corresponds to all.vars)
│   ├── infra.yml          # infra group variables
│   ├── etcd.yml           # etcd group variables
│   └── pg-meta.yml        # pg-meta cluster variables
└── host_vars/
    ├── 10.10.10.10.yml    # Specific host variables
    └── 10.10.10.11.yml

You can place cluster member definitions in the hosts.yml file and put cluster-level configuration parameters in corresponding files under the group_vars directory.

Switching Configuration

You can temporarily specify a different inventory file when running playbooks using the -i parameter.

./pgsql.yml -i another_config.yml
./infra.yml -i nginx_config.yml

Additionally, Ansible supports multiple configuration methods. You can use local yaml|ini configuration files, or use CMDB and any dynamic configuration scripts as configuration sources.

In Pigsty, we specify pigsty.yml in the same directory as the default inventory through ansible.cfg in the Pigsty home directory. You can modify it as needed.

[defaults]
inventory = pigsty.yml

Additionally, Pigsty supports using a CMDB metabase to store the inventory, facilitating integration with existing systems.