enix.postgresql_replication

A role for deploying and configuring postgresql replication cluster on unix hosts using Ansible.

Requirements

Supported targets:

• Debian 8 "Jessie"
• Debian 9 "Stretch"

Role Variables

This roles comes preloaded with almost every available default. You can override each one in your hosts/group vars, in your inventory, or in your play. See the annotated defaults in defaults/main.yml for help in configuration. All provided variables start with postgresql_replication__.

This role work in a different way than several others in a way that in order to make different cluster hosts roles independent we use ansible groups. There is so 3 different groups to define in your inventory. to make this usable with different clusters in the same inventory they are configurable.

• postgresql_replication__group - the main group of hosts for this cluster, default: postgresql
• postgresql_replication__group_master - the master group that must include only one host, default: postgresql_master
• postgresql_replication__group_replicas - the group including the replicas hosts, default: postgresql_replicas Your inventory must have in final this form (yaml format exemple):

all:
  children:
    postgresql:
      children:
        postgresql_master:
          hosts:
            db-01:
              ansible_host: 185.145.251.12
        postgresql_replicas:
          hosts:
            db-02:
              ansible_host: 185.145.251.243

• postgresql_replication__user - the username to use for authentification of replication nodes. default : replicate.
• postgresql_replication__password - the postgresql_replication__user password. It is important to change default on production clusters. default: replicate.
• postgresql_replication__waldir - Directory used to store WAL file sent from the master node to the replication nodes.

Sending servers configuration. See (https://www.postgresql.org/docs/11/runtime-config-replication.html#RUNTIME-CONFIG-REPLICATION-SENDER) for details of correct values for your setup.

• postgresql_replication__walsenders - Number of wal sender processes to enable. default : 3.

• postgresql_replication__walsegments - Number of wal segments to keep (16MB each). default: 64.

• postgresql_replication__trigger_file - File used to trigger master operation on a slave node. default: /tmp/MasterNow

• postgresql_replication__bootstrap - Very important. when this variable is set to "yesiwant" the deployement will remove all datas on hosts defined in postgresql_replication__group_replicas and proceed with a fresh pg_basebackup from the master. Take care as if you enable this and do not properly setup hosts in groups you can completely destroy you datas.

Dependencies

• enix.postgresql

Usage

Use Ansible galaxy requirements.yml

- src: enix.postgresql_replication

And add it to your play's roles:

- hosts: postgresql
  roles:
    - role enix.postgresql_replication:
        postgresql__version: 11
        postgresql__global_config_options:
          - option: listen_addresses
            value: '*'
          - option: log_min_duration_statement
            value: 1000
        postgresql__hba_entries:
          - {type: local, database: all, user: postgres, auth_method: peer}
          - {type: local, database: all, user: all, auth_method: peer}
          - {type: host, database: all, user: all, address: "0.0.0.0/0", auth_method: md5}
          - {type: hostssl, database: replication, user: "{{ postgresql_replication__user }}", address: "0.0.0.0/0" ,auth_method: md5}
        postgresql__users:
          - {name: "{{ postgresql_replication__user }}", password: "{{ postgresql_replication__password }}", role_attr_flags: "REPLICATION"}

You can also use the role as a playbook. You will be asked which hosts to provision, and you can further configure the play by using --extra-vars.

$ ansible-playbook -i inventory --extra-vars='{...}' main.yml

Still to do

• Add real gitlab / travis CI
• Add tests using molecule

Changelog

1.1.0

Update group names to postgresql_master and postgresql_replicas. Comply with ansible 2.8+ group names requirements

1.0.0

Initial version.

License

GPLv2

Author Information

Laurent CORBES laurent.corbes@enix.fr - http://www.enix.io