observability.svc.plus/roles/node_id

Role: node_id

Derive Node Identity and Operating System Information

Module	NODE
Docs	https://pigsty.io/docs/node/
Related Roles	node, node_monitor, node_remove, pg_id

Overview

The node_id role gathers and calculates node identity information. It runs as a prerequisite for most node operations and always runs with the always tag.

This role collects:

• Operating system information (vendor, version, architecture)
• Node resources (CPU count, memory size)
• Node identity (nodename, node_cluster)
• OS-specific variables (package manager, paths)

It runs on target hosts to gather facts, then processes them on the control node.

Playbooks

This role is included in most playbooks as a prerequisite:

Playbook	Description
node.yml	Full node provisioning
pgsql.yml	PostgreSQL deployment
redis.yml	Redis deployment
etcd.yml	ETCD deployment
minio.yml	MinIO deployment

File Structure

roles/node_id/
├── defaults/
│   └── main.yml              # Default identity parameters
├── meta/
│   └── main.yml              # Role dependencies
├── tasks/
│   └── main.yml              # Identity derivation logic
└── vars/                     # OS-specific variables (~700 vars each)
    ├── el7.x86_64.yml        # EL7 x86_64 (legacy, EOL)
    ├── el8.x86_64.yml        # EL8 x86_64
    ├── el8.aarch64.yml       # EL8 ARM64
    ├── el9.x86_64.yml        # EL9 x86_64
    ├── el9.aarch64.yml       # EL9 ARM64
    ├── el10.x86_64.yml       # EL10 x86_64
    ├── el10.aarch64.yml      # EL10 ARM64
    ├── d12.x86_64.yml        # Debian 12 x86_64
    ├── d12.aarch64.yml       # Debian 12 ARM64
    ├── d13.x86_64.yml        # Debian 13 x86_64
    ├── d13.aarch64.yml       # Debian 13 ARM64
    ├── u22.x86_64.yml        # Ubuntu 22 x86_64
    ├── u22.aarch64.yml       # Ubuntu 22 ARM64
    ├── u24.x86_64.yml        # Ubuntu 24 x86_64
    └── u24.aarch64.yml       # Ubuntu 24 ARM64

Tags

node-id (always)               # Node identity derivation

The role runs with tags: [always, node-id], ensuring it executes regardless of tag filters.

Derived Variables

Operating System

Variable	Example	Description
os_vendor	ubuntu	OS distribution
os_version	22	Major version number
os_version_full	22.04	Full version string
os_codename	jammy	Debian/Ubuntu codename or el9
os_arch	x86_64	CPU architecture
os_package	deb	Package manager type (deb/rpm)

Node Resources

Variable	Example	Description
node_cpu	4	Number of CPU cores
node_mem_bytes	8589934592	Memory in bytes
node_mem_mb	8192	Memory in MB
node_mem_gb	8	Memory in GB (rounded up)

Node Identity

Variable	Example	Description
nodename	pg-test-1	Node name
node_cluster	pg-test	Node cluster name
node_hostname	node-1	Original hostname
node_os_code	el9, u22	Short OS code

Input Variables

Variable	Default	Description
nodename	(auto)	Override node name
node_cluster	nodes	Default cluster name
node_id_from_pg	true	Derive nodename from pg_cluster/pg_seq
nodename_overwrite	true	Overwrite hostname with nodename
nodename_exchange	false	Exchange nodename among play hosts

Note

: nodename_overwrite and nodename_exchange are defined here but used by the node role. They control whether the derived nodename is applied to the system hostname and shared across hosts via /etc/hosts.

Identity Derivation

The nodename is determined by priority:

1. Explicit nodename: If set in inventory, use it directly
2. PostgreSQL identity: If node_id_from_pg=true and pg_cluster/pg_seq exist, use <pg_cluster>-<pg_seq>
3. System hostname: Fallback to the node's original hostname

The node_cluster follows similar logic:

1. Explicit node_cluster: If set (not nodes), use it directly
2. PostgreSQL cluster: If node_id_from_pg=true and pg_cluster exists, use it
3. Default: Use nodes

OS-Specific Variables

Each vars file (vars/<os_code>.<arch>.yml) provides ~700 variables including:

• systemd_dir: Path to systemd service files
• node_packages_default: Default packages to install
• infra_packages_default: Infrastructure packages
• repo_upstream_default: Repository configurations
• pg_home_map: PostgreSQL installation paths

Fallback Mechanism: If the detected OS code doesn't have a vars file, the role falls back to: el10 (rpm), u24 (ubuntu), d12 (debian).

Supported Operating Systems

OS	Code	Package	Note
RHEL/Rocky 7	el7	rpm	Legacy, x86_64 only, EOL
RHEL/Rocky 8	el8	rpm
RHEL/Rocky 9	el9	rpm
RHEL/Rocky 10	el10	rpm
Debian 12	d12	deb
Debian 13	d13	deb
Ubuntu 22.04	u22	deb
Ubuntu 24.04	u24	deb

See Also

• node: Node provisioning
• pg_id: PostgreSQL identity derivation
• NODE Configuration: Configuration documentation