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 conf/

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)

Template

There are numerous preset config templates for different scenarios under the conf/ directory.

During configure process, you can specify a template using the -c parameter. Otherwise, the single-node installation config template will be automatically selected based on your OS distribution.

Details about this built-in configuration files can be found @ Configuration

Switch Config Inventory

To use a different config inventory, you can copy & paste the content into the pigsty.yml file in the home dir as needed.

You can also explicitly specify the config inventory file to use when executing Ansible playbooks by using the -i command-line parameter, for example:

./node.yml -i files/pigsty/rpmbuild.yml    # use another file as config inventory, rather than the default pigsty.yml

If you want to modify the default config inventory filename, you can change the inventory parameter in the ansible.cfg file in the home dir to point to your own inventory file path. This allows you to run the ansible-playbook command without explicitly specifying the -i parameter.

Pigsty allows you to use a database (CMDB) as a dynamic configuration source instead of a static configuration file. Pigsty provides three convenient scripts:

• bin/inventory_load: Loads the content of the pigsty.yml into the local PostgreSQL database (meta.pigsty)
• bin/inventory_cmdb: Switches the configuration source to the local PostgreSQL database (meta.pigsty)
• bin/inventory_conf: Switches the configuration source to the local static configuration file pigsty.yml

Reference

Pigsty have 280+ parameters, check Parameter for details.