Book Image

PostgreSQL High Availability Cookbook - Second Edition

By : Shaun Thomas
Book Image

PostgreSQL High Availability Cookbook - Second Edition

By: Shaun Thomas

Overview of this book

Databases are nothing without the data they store. In the event of a failure - catastrophic or otherwise - immediate recovery is essential. By carefully combining multiple servers, it’s even possible to hide the fact a failure occurred at all. From hardware selection to software stacks and horizontal scalability, this book will help you build a versatile PostgreSQL cluster that will survive crashes, resist data corruption, and grow smoothly with customer demand. It all begins with hardware selection for the skeleton of an efficient PostgreSQL database cluster. Then it’s on to preventing downtime as well as troubleshooting some real life problems that administrators commonly face. Next, we add database monitoring to the stack, using collectd, Nagios, and Graphite. And no stack is complete without replication using multiple internal and external tools, including the newly released pglogical extension. Pacemaker or Raft consensus tools are the final piece to grant the cluster the ability to heal itself. We even round off by tackling the complex problem of data scalability. This book exploits many new features introduced in PostgreSQL 9.6 to make the database more efficient and adaptive, and most importantly, keep it running.
Table of Contents (18 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Adding an e-mail alert

The last thing we are going to add should be considered a requirement when building a high-availability PostgreSQL cluster. Any time the status of Pacemaker changes; we can have it transmit an e-mail alerting us to the activity. Not only is this possible with Pacemaker, it's relatively easy to set up.

This recipe will outline the steps necessary to add an e-mail alert to Pacemaker.

Getting ready

As we're continuing to configure Pacemaker, make sure you've followed all the previous recipes.

How to do it...

Perform these steps on any Pacemaker node as the root user:

  1. Add an e-mail primitive to Pacemaker with crm:
crm configure primitive pg_mail ocf:heartbeat:MailTo \        params email="[email protected]" \              subject="Pacemaker\ cluster\ status\ changed:\ "
  1. Clean up any errors that might have accumulated with crm:
crm resource cleanup pg_mail
  1. Display the status of our new e-mail alert with crm:
crm resource status

How it works...

To add an e-mail alert, we need to configure...