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pg_auto_failover_ansible

Ansible Playbook(s) to create a cluster of PostgreSQL nodes running in a Ubuntu cluster with pg_auto_failover.

Current features

Automatically setup a secure cluster with 1 monitor node and 2 database nodes with synchronous replication
Support for Ubuntu 18.04/Ubuntu 20.04
Support for PostgreSQL 12/13/14
Support for rudimentary pgbouncer setup (not enabled by default)

Not features

The installation script for pg_auto_failover roles/postgres-cluster-pg-auto-failover-install/files/deb.sh was manually downloaded from the citus homepage. To update it, you have to replace it manually.
Removal of old nodes has to be done manually. New data nodes can be added to the cluster by just running all playbooks again.
NO automatic configuration of backups - Replication does NOT replace regular backups!
By default this playbook leaves the default clusters that might be present on your machines after installation and uses a different port than the default (5433 - this is configurable)
HAProxy setup is out of scope of this project as it is common to run HAProxy on the application servers themselves. A sample config can be found in the wiki

Configuration

While we do not have a full tutorial on all configuration options a good place to start is in the test directory. There you can also find Vagrant based tests to take the playbooks for a spin.

Used Software

The following roles are based on geerlingguy's work but heavily modified to work with pg_auto_failover

passbolt-cluster-configure
passbolt-cluster-hba-config
passbolt-cluster-install

Upgrading pg_auto_failover (NOT postgres itself)

When upgrading, please follow this procedure:

When upgrading from a version <= 1.3:

run the postgres_cluster_upgrade_pre_1.4.yml playbook with extra-vars --extra-vars='{"postgresql_new_pg_auto_failover_version": "1.4"}' to upgrade to the version you want to upgrade to
update the inventory to reflect the new pg_auto_failover version

When upgrading from a version >= 1.4:

NOTE: starting at 1.4 pg_auto_failover has a new upgrade scheme, we will provide a playbook to facilitate upgrades once a version > 1.4 is out. The procedure will be similar.

Testing

Requirements:

vagrant
virtualbox
psql

To test out the functionality and/or want to run the tests for this project, go to test/ and run bash setup_for_test.sh and then run.sh.

Usage

Setup Inventory

Go to inventories/pg_auto_failover/hosts.yml and adjust the ips of your hosts according to your requirements.
Put your root ssh key under ssh_keys/root_rsa.

Setup certificates

0. fix all certificate information strings

Update certs/pg_auto_failover/gen_root_cert.sh and certs/certs/pg_auto_failover/gen_server_cert.sh to contain all the correct properties for your certificates. (Fix all occurences of your-company).

1. create new root certificate

Update file certs/pg_auto_failover/recreate_root_cert.sh according to your requirements (passworded certificate is not used here, but it is a good idea to set a separate one for each deployment you are using this in)

Then, run:

cd certs/pg_auto_failover
bash recreate_root_cert.sh

2. generate server certificates

Update file certs/pg_auto_failover/recreate_server_certs.sh. Paths should correspond to the hostnames in your ansible inventory

Then, run:

cd certs/pg_auto_failover
bash recreate_server_certs.sh

This will copy all certificates into the correct place for them to be picked up by ansible.

Run base setup

remove existing ssh keys of you machines into your known hosts (only run this if you have rebuilt your machines and the ssh key has changed):

For each relevant node run:
```
ssh-keygen -f ~/.ssh/known_hosts <ip>
```
put the ssh keys of your machines into your known hosts:

For each node run:
```
ssh-keyscan <ip> >> ~/.ssh/known_hosts
```

Run the actual base_setup playbook

ansible-playbook -i inventories/pg_auto_failover/hosts.yml base_setup.yml

Run the actual cluster setup

ansible-playbook -i inventories/pg_auto_failover/hosts.yml postgres_cluster_servers.yml

Verify setup

ssh -i ssh_keys/root_rsa root@<manager-ip>
sudo su postgres
XDG_RUNTIME_DIR="" pg_autoctl show state --pgdata  /var/lib/postgresql/12/main_cluster/

If everything is okay, you should be greeted with the following:

Next steps

Setup pg_hba config in inventory configuration to allow connection to all the databases you will create/need
create all databases

Connection to the cluster

Just ask the monitor node :)

XDG_RUNTIME_DIR="" pg_autoctl show uri --pgdata  /var/lib/postgresql/12/main_cluster/

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