Role: pg_remove

Remove PostgreSQL Cluster/Instance from Nodes

Module	PGSQL
Docs	https://pigsty.io/docs/pgsql/admin/#remove-cluster
Related Roles	`pgsql`, `pg_id`, `node_id`

Overview

The pg_remove role is a DANGEROUS role that removes PostgreSQL clusters or instances from target nodes. It performs the reverse operation of the pgsql role, cleaning up:

Monitoring targets (Victoria Metrics, Grafana datasources, Vector logs)
Exporters (pg_exporter, pgbouncer_exporter, pgbackrest_exporter)
Access layer (HAProxy services, VIP, DNS records, pgBouncer)
PostgreSQL instances (Patroni, Postgres)
Backup data (pgBackRest repo)
Data directories
PostgreSQL packages

WARNING: This role can cause DATA LOSS. Always ensure proper backups before execution.

Playbooks

Playbook	Description
`pgsql-rm.yml`	Remove PostgreSQL cluster/instance

File Structure

roles/pg_remove/
├── defaults/
│   └── main.yml              # Default variables
├── meta/
│   └── main.yml              # Role dependencies
└── tasks/
    ├── main.yml              # Entry point: orchestrates removal
    ├── victoria.yml          # [rm_metrics] Remove from Victoria Metrics
    ├── grafana.yml           # [rm_ds] Remove Grafana datasources
    ├── pg_exporter.yml       # [pg_exporter] Remove pg_exporter
    ├── pgbouncer_exporter.yml # [pgbouncer_exporter] Remove pgbouncer_exporter
    ├── pgbackrest_exporter.yml # [pgbackrest_exporter] Remove pgbackrest_exporter
    ├── dns.yml               # [rm_dns] Remove DNS records
    ├── vip.yml               # [vip] Remove VIP manager
    ├── pg_service.yml        # [pg_service] Remove HAProxy services
    ├── pgbouncer.yml         # [pgbouncer] Remove pgBouncer
    ├── postgres.yml          # [postgres] Stop and remove Patroni/Postgres
    ├── pgbackrest.yml        # [pgbackrest] Remove backup repo
    └── uninstall.yml         # [pg_pkg] Uninstall packages

Tags

Tag Hierarchy

pg_remove (full role)
│
├── pg_safeguard               # Safeguard check (always runs)
│
├── pg_monitor                 # Remove monitoring components
│   ├── pg_deregister          # Deregister from infra
│   │   ├── rm_metrics         # Remove from Victoria Metrics
│   │   ├── rm_ds              # Remove Grafana datasources
│   │   └── rm_logs            # Remove Vector log sources
│   ├── pg_exporter            # Remove pg_exporter
│   ├── pgbouncer_exporter     # Remove pgbouncer_exporter
│   └── pgbackrest_exporter    # Remove pgbackrest_exporter
│
├── pg_access                  # Remove access layer
│   ├── dns                    # Remove DNS records
│   ├── vip                    # Remove VIP manager
│   ├── pg_service / haproxy   # Remove HAProxy services
│   └── pgbouncer              # Remove pgBouncer
│
├── pg_bootstrap               # Remove PostgreSQL
│   └── postgres / patroni     # Stop Patroni and Postgres
│       ├── pg_replica         # Remove replicas first
│       ├── pg_primary         # Remove primary instance
│       └── pg_meta            # Remove DCS metadata
│
├── pg_backup                  # Remove backup (if pg_rm_backup=true)
│   └── pgbackrest             # Remove pgBackRest stanza
│
├── pg_data                    # Remove data (if pg_rm_data=true)
│
└── pg_pkg                     # Uninstall packages (if pg_rm_pkg=true)
    └── pg_ext                 # Uninstall extensions only

Usage Examples

# Remove monitoring only
./pgsql-rm.yml -l pg-test -t pg_monitor

# Remove access layer only
./pgsql-rm.yml -l pg-test -t pg_access

# Remove PostgreSQL without touching packages/data
./pgsql-rm.yml -l pg-test -t postgres

# Uninstall packages only
./pgsql-rm.yml -l pg-test -t pg_pkg -e pg_rm_pkg=true

Key Variables

Control Variables

Variable	Default	Description
`pg_safeguard`	`false`	Safeguard to prevent accidental removal
`pg_rm_data`	`true`	Remove PostgreSQL data directories
`pg_rm_backup`	`true`	Remove pgBackRest backup (primary only)
`pg_rm_pkg`	`true`	Uninstall PostgreSQL packages

Identity (Reference)

Variable	Level	Description
`pg_cluster`	CLUSTER	Target cluster name
`pg_role`	INSTANCE	Instance role
`pg_seq`	INSTANCE	Instance sequence

Paths (Reference)

Variable	Default	Description
`pg_data`	`/pg/data`	PostgreSQL data directory
`pg_fs_main`	`/data/postgres`	Main filesystem path
`pg_namespace`	`/pg`	etcd namespace

Safeguard Protection

The role includes a safeguard mechanism to prevent accidental cluster removal:

# In pigsty.yml, set safeguard for critical clusters
pg-prod:
  vars:
    pg_safeguard: true  # Prevents accidental removal

To override safeguard:

./pgsql-rm.yml -l pg-prod -e pg_safeguard=false

Removal Order

The removal process follows a specific order to ensure clean teardown:

Monitoring - Deregister from monitoring systems first
Access Layer - Remove services, VIP, DNS, pgBouncer
Replicas - Remove replica instances before primary
Primary - Remove primary instance
Metadata - Clean up DCS (etcd) entries
Backup - Remove pgBackRest repo (optional)
Data - Remove data directories (optional)
Packages - Uninstall software (optional)

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