Parameters

The ETCD module has 13 parameters, divided into two sections:

• ETCD: 10 parameters for etcd cluster deployment and configuration
• ETCD_REMOVE: 3 parameters for controlling etcd cluster removal

Parameter Overview

The ETCD parameter group is used for etcd cluster deployment and configuration, including instance identification, cluster name, data directory, ports, and authentication password.

The ETCD_REMOVE parameter group controls etcd cluster removal behavior, including safeguard protection, data cleanup, and package uninstallation.

ETCD

This section contains parameters for the etcd role, which are used by the etcd.yml playbook.

Parameters are defined in roles/etcd/defaults/main.yml

#etcd_seq: 1                      # etcd instance identifier, explicitly required
etcd_cluster: etcd                # etcd cluster & group name, etcd by default
etcd_learner: false               # run etcd instance as learner? default is false
etcd_data: /data/etcd             # etcd data directory, /data/etcd by default
etcd_port: 2379                   # etcd client port, 2379 by default
etcd_peer_port: 2380              # etcd peer port, 2380 by default
etcd_init: new                    # etcd initial cluster state, new or existing
etcd_election_timeout: 1000       # etcd election timeout, 1000ms by default
etcd_heartbeat_interval: 100      # etcd heartbeat interval, 100ms by default
etcd_root_password: Etcd.Root     # etcd root user password for RBAC authentication (please change!)

etcd_seq

Parameter: etcd_seq, Type: int, Level: I

etcd instance identifier. This is a required parameter—you must assign a unique identifier to each etcd instance.

Here is an example of a 3-node etcd cluster with identifiers 1 through 3:

etcd: # dcs service for postgres/patroni ha consensus
  hosts:  # 1 node for testing, 3 or 5 for production
    10.10.10.10: { etcd_seq: 1 }  # etcd_seq required
    10.10.10.11: { etcd_seq: 2 }  # assign from 1 ~ n
    10.10.10.12: { etcd_seq: 3 }  # use odd numbers
  vars: # cluster level parameter override roles/etcd
    etcd_cluster: etcd  # mark etcd cluster name etcd
    etcd_safeguard: false # safeguard against purging

etcd_cluster

Parameter: etcd_cluster, Type: string, Level: C

etcd cluster & group name, default value is the hard-coded etcd.

You can modify this parameter when you want to deploy an additional etcd cluster for backup purposes.

etcd_learner

Parameter: etcd_learner, Type: bool, Level: I/A

Initialize etcd instance as learner? Default value is false.

When set to true, the etcd instance will be initialized as a learner, meaning it cannot participate in voting elections within the etcd cluster.

Use Cases:

• Cluster Expansion: When adding new members to an existing cluster, using learner mode prevents affecting cluster quorum before data synchronization completes
• Safe Migration: In rolling upgrade or migration scenarios, join as a learner first, then promote after confirming data synchronization

Workflow:

1. Set etcd_learner: true to initialize the new member as a learner
2. Wait for data synchronization to complete (check with etcdctl endpoint status)
3. Use etcdctl member promote <member_id> to promote it to a full member

etcd_data

Parameter: etcd_data, Type: path, Level: C

etcd data directory, default is /data/etcd.

etcd_port

Parameter: etcd_port, Type: port, Level: C

etcd client port, default is 2379.

etcd_peer_port

Parameter: etcd_peer_port, Type: port, Level: C

etcd peer port, default is 2380.

etcd_init

Parameter: etcd_init, Type: enum, Level: C

etcd initial cluster state, can be new or existing, default value: new.

Option Values:

Important Notes:

Usage Examples:

# Create new cluster (default behavior)
./etcd.yml

# Add new member to existing cluster
./etcd.yml -l <new_ip> -e etcd_init=existing

# Or use the convenience script (automatically sets etcd_init=existing)
bin/etcd-add <new_ip>

etcd_election_timeout

Parameter: etcd_election_timeout, Type: int, Level: C

etcd election timeout, default is 1000 (milliseconds), i.e., 1 second.

etcd_heartbeat_interval

Parameter: etcd_heartbeat_interval, Type: int, Level: C

etcd heartbeat interval, default is 100 (milliseconds).

etcd_root_password

Parameter: etcd_root_password, Type: password, Level: G

etcd root user password for RBAC authentication, default value is Etcd.Root.

Pigsty v4.0 enables etcd RBAC (Role-Based Access Control) authentication by default. During cluster initialization, the etcd_auth task automatically creates the root user and enables authentication.

Password Storage Location:

• Password is stored in /etc/etcd/etcd.pass file
• File permissions are 0640 (owned by root, readable by etcd group)
• The etcdctl environment script /etc/profile.d/etcdctl.sh automatically reads this file

Integration with Other Components:

• Patroni uses the pg_etcd_password parameter to configure the password for connecting to etcd
• If pg_etcd_password is empty, Patroni will use the cluster name as password (not recommended)
• VIP-Manager also requires the same authentication credentials to connect to etcd

Security Recommendations:

etcd_root_password: 'YourSecurePassword'

ETCD_REMOVE

This section contains parameters for the etcd_remove role, which are action flags used by the etcd-rm.yml playbook.

Parameters are defined in roles/etcd_remove/defaults/main.yml

etcd_safeguard: false             # prevent purging running etcd instances?
etcd_rm_data: true                # remove etcd data and config files during removal?
etcd_rm_pkg: false                # uninstall etcd packages during removal?

etcd_safeguard

Parameter: etcd_safeguard, Type: bool, Level: G/C/A

Safeguard to prevent purging running etcd instances? Default value is false.

When enabled, the etcd-rm.yml playbook will abort when detecting running etcd instances, preventing accidental deletion of active etcd clusters.

Recommended Settings:

In emergencies, you can override the configuration with command-line parameters:

./etcd-rm.yml -e etcd_safeguard=false

etcd_rm_data

Parameter: etcd_rm_data, Type: bool, Level: G/C/A

Remove etcd data and configuration files during removal? Default value is true.

When enabled, the etcd-rm.yml playbook will delete the following contents when removing a cluster or member:

• /etc/etcd/ - Configuration directory (including certificates and password files)
• /var/lib/etcd/ - Alternate data directory
• {{ etcd_data }} - Primary data directory (default /data/etcd)
• {{ systemd_dir }}/etcd.service - Systemd service unit file
• /etc/profile.d/etcdctl.sh - Client environment script
• /etc/vector/etcd.yaml - Vector log collection config

Use Cases:

# Stop service only, preserve data
./etcd-rm.yml -e etcd_rm_data=false

etcd_rm_pkg

Parameter: etcd_rm_pkg, Type: bool, Level: G/C/A

Uninstall etcd packages during removal? Default value is false.

When enabled, the etcd-rm.yml playbook will uninstall etcd packages when removing a cluster or member.

Use Cases:

# Uninstall packages during removal
./etcd-rm.yml -e etcd_rm_pkg=true