What is Memcached :

Memcached is an open-source, high-performance, distributed memory object caching system. It is designed to cache data and objects in RAM to reduce the number of database requests, improving the response times of dynamic web applications. Memcached is lightweight and fast, making it popular for scenarios where frequently accessed data needs to be quickly retrievable without reloading from a slower back-end store. Memcached can store any arbitrary data, such as results from database queries, API calls, or complex calculations, making it particularly useful for high-traffic websites and applications where speed is critical.

Installing Memcached on an Ubuntu VPS

To install and configure Memcached on an Ubuntu-based VPS, follow the steps below.

Start by ensuring that your system is up-to-date:

You can install Memcached using the default Ubuntu package repository. Use the following command:

Once installed, you can verify if Memcached is running by checking its status:

You should see output indicating that the service is active and running. If Memcached is not running, you can start it with:

You can also enable Memcached to start on system boot:

The default configuration file for Memcached is located at /etc/memcached.conf. You may want to modify certain settings depending on your server specifications and requirements.

Open the configuration file using a text editor like nano:

Key settings you might want to adjust:

After making your changes, save and exit the file (press CTRL + X, then Y, followed by ENTER), and restart Memcached to apply the new settings:

Depending on your programming environment, you may need to install a Memcached client library. For example, if you are using PHP, you can install the PHP Memcached extension as follows:

Example: Basic Usage of Memcached

Let’s walk through an example of using Memcached to store and retrieve cached data.

You can use telnet to connect to the Memcached server and perform simple operations. First, install telnet if it’s not already available:

Now, connect to the Memcached server (running on localhost by default):

Once connected, you can perform basic Memcached operations like storing and retrieving data.

To store data in Memcached, you use the set command, which follows this syntax:

Here’s an example:

In this example:

After the command, you should see the response STORED, indicating that the data was successfully cached.

To retrieve the cached data, use the get command:

Memcached will return:

This shows that the key example_key is stored with the value memcached.

You can delete a key using the delete command:

If you're developing in PHP, here's an example of how to use Memcached within your PHP code:

In this example:

Securing Memcached

Memcached, by default, is not secure for external use as it does not provide authentication or encryption. To secure Memcached:

1. Bind Memcached to localhost: Ensure Memcached is only accessible from localhost by making sure the following line is in /etc/memcached.conf:

2. Use a Firewall: Restrict access to Memcached using a firewall such as ufw. Allow access only from trusted sources if you need remote access:

3. Memcached SASL Authentication: For a more secure setup in multi-user environments, you can enable SASL authentication (available in some versions of Memcached).

Memcached is a powerful tool for speeding up applications by caching frequently accessed data in memory. By following this guide, you should now have Memcached installed and configured on your Ubuntu VPS. With basic commands and client-side integration, you can leverage Memcached’s caching capabilities to improve the performance and scalability of your web applications.