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How To Optimize WordPress Performance With MySQL Replication On Ubuntu 14.04

10/05/2024 Comments off

Introduction

In this tutorial, we will teach you how to scale up your WordPress MySQL database server setup using master-slave database replication and the HyperDB plugin for WordPress. Adding more database servers to your environment in this manner allows your WordPress application to read from multiple database servers, increasing read performance.

MySQL replication reaps the most performance benefits for a system that processes frequent reads and infrequent writes, like most WordPress installations. By using a single-master with multiple-slave setup, you can add more slaves to scale your system, until you run out of network bandwidth or your master cannot handle the update load. If you wish, you can add more than one slaves by repeating the « slave » portions of the replication sections of this tutorial.

We are assuming that your setup includes two load balanced WordPress application servers that connect to a separate MySQL database server (see the prerequisites for a tutorial on how to set that up). It is not strictly necessary to have load balanced application servers to follow this tutorial, but your MySQL database server should be separate from your application servers.

Prerequisites

Before continuing with this tutorial, you should have completed two tutorials or have a similar environment:

After following those tutorials, to set up WordPress with two load balanced web application servers and a separate database server, you should have four VPSs. Because we will be dealing with several VPSs, for reference purposes, we will call your four existing VPSs the following:

  • haproxy-www: Your HAProxy server for layer 4 load balancing your WordPress web application servers. This is the entry point into your website
  • wordpress-1: Your first WordPress web application server
  • wordpress-2: Your second WordPress web application server
  • mysql-1: Your MySQL server for WordPress

That is, your environment should look something like this:

WordPress and Separate MySQL Database Server

In addition to your current environment, we will require one additional VPS during this tutorial. We will call it:

  • mysql-2: Your slave MySQL database server

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How To Isolate Servers Within A Private Network Using Iptables

05/07/2021 Comments off

Source: DigitalOcean – Mitchell Anicas

Introduction

In this tutorial, we will teach you how to use a Iptables with shared private networking to simulate the network traffic isolation that a true private network can provide. We will also cover why you would want to do this, and provide an example of how to implement this in your own environment. The example should explain the concept well enough that you should be able to adapt the configuration to your own needs.

DigitalOcean’s private networking option grants a second networking interface to a VPS, which is only accessible to other VPSs in the same datacenter–which includes the VPSs of other customers in the same datacenter. This is known as shared private networking. This means that data sent over a VPS’s private interface does not leave the datacenter at all, and no billable bandwidth usage will be incurred.

At the time of this writing, DigitalOcean offers the private networking option for VPSs in the following data centers:

  • Amsterdam 2
  • New York 2
  • Singapore 1

Note: This tutorial covers IPv4 security. In Linux, IPv6 security is maintained separately from IPv4. For example, iptables only maintains firewall rules for IPv4 addresses but it has an IPv6 counterpart called ip6tables, which can be used to maintain firewall rules for IPv6 network addresses.

If your VPS is configured for IPv6, please remember to secure both your IPv4 and IPv6 network interfaces with the appropriate tools. For more information about IPv6 tools, refer to this guide: How To Configure Tools to Use IPv6 on a Linux VPS

Example Scenario

For our example, we will use the environment created by the following tutorial: How To Optimize WordPress Performance With MySQL Replication On Ubuntu 14.04.

Here is a diagram of what the environment looks like:

prereq_no_private

The example environment uses five VPSs (and iptables are not configured):

  • haproxy-www: Reverse proxy load balancer
  • wordpress-1: First application server
  • wordpress-2: Second application server
  • mysql-1: Master MySQL database server
  • mysql-2: Slave MySQL database server

If your setup doesn’t look like this, you should still be able to follow along. Also, if you would like to read up on setting up a VPS with private networking or iptables basics, here are a few links that you might find to be useful (this tutorial assumes you know the basics of iptables):

If you are already familiar with the concepts, and would like to see the iptables setup, feel free to skip to the Overview of Iptables Configuration section.

Our Goal

When we are finished with this tutorial, we should have an environment that looks something like the following diagram:

goal

All of the servers in the private network area can only be communicated with by other servers within this private network (the orange box). The load balancer will be accessible via the Internet and also be linked to the private network. The enforcement of this policy will be implemented via iptables on each server.

Note: To block traffic to your public interface, you can either disable your public interface or set up firewall rules to achieve a similar effect with Iptables. We will go with the firewall option because we can configure it block unwanted network traffic, while allowing our server to access the Internet when it initiates the connection (this is useful for things like downloading updates on the server).

How To Create a High Availability Setup with Heartbeat and Floating IPs on Ubuntu 14.04

01/07/2021 Comments off

Source: Digital Ocean – Mitchell Anicas

Introduction

Heartbeat is an open source program that provides cluster infrastructure capabilities—cluster membership and messaging—to client servers, which is a critical component in a high availability (HA) server infrastructure. Heartbeat is typically used in conjunction with a cluster resource manager (CRM), such as Pacemaker, to achieve a complete HA setup. However, in this tutorial, we will demonstrate how to create a 2-node HA server setup by simply using Heartbeat and a DigitalOcean Floating IP.

If you are looking to create a more robust HA setup, look into using Corosync and Pacemaker or Keepalived.

Goal

When completed, the HA setup will consist of two Ubuntu 14.04 servers in an active/passive configuration. This will be accomplished by pointing a Floating IP, which is how your users will access your services or website, to point to the primary, or active, server unless a failure is detected. In the event that the Heartbeat service detects that the primary server is unavailable, the secondary server will automatically run a script to reassign the Floating IP to itself via the DigitalOcean API. Thus, subsequent network traffic to the Floating IP will be directed to your secondary server, which will act as the active server until the primary server becomes available again (at which point, the primary server will reassign the Floating IP to itself).

ha-diagram-animated

Note: This tutorial only covers setting up active/passive high availability at the gateway level. That is, it includes the Floating IP, and the load balancer servers—Primary and Secondary. Furthermore, for demonstration purposes, instead of configuring reverse-proxy load balancers on each server, we will simply configure them to respond with their respective hostname and public IP address.

To achieve this goal, we will follow these steps:

  • Create 2 Droplets that will receive traffic
  • Create Floating IP and assign it to one of the Droplets
  • Create DNS A record that points to Floating IP (optional)
  • Install Heartbeat on Droplets
  • Configure Heartbeat to Run Floating IP Reassignment Service
  • Create Floating IP Reassignment Service
  • Test failover

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