A reference application is a sample application that is used as a guide for developers to learn and implement best practices for software development, testing, deployment, and operations within a specific technology stack or framework. It can serve as a blueprint for building and maintaining similar applications and can be used to demonstrate the use of tools, processes, and techniques for achieving high levels of automation, scalability, and reliability.

If you are learning how to deploy applications to Kubernetes of Virtual Machines in cloud, create your own tiny application.

NFS Server

To run your own NFS (Network File System) server, you’ll need to first install Linux on your server. I’d go with Debian, Ubuntu or CentOS distributions. Once you’ve done that, you can install the NFS server software, which is typically included with most Linux distributions. After the NFS server software is installed, you’ll need to configure it to specify which directories on the server should be shared with NFS clients, and what type of access they should have. This typically involves editing the server’s configuration file, which is typically located at /etc/exports. Once the server is configured, you can start the NFS server and begin sharing files with NFS clients. To access the shared files, the NFS clients will need to mount the NFS share using the mount command.

syslog

Syslog is a standard for logging system events on Unix and Linux systems. It is typically used to collect and store log messages from various applications and system components, such as the kernel, system libraries, and applications. Syslog uses a client-server model, where each client application sends log messages to a central syslog server, which then stores the messages in a log file. The syslog server can also forward the log messages to other syslog servers or send them to a log management system for further analysis. Syslog uses a simple text-based format for its log messages, which makes it easy to read and analyze. It also supports multiple levels of severity, allowing applications to categorize their log messages based on importance.

There are many tools and software programs that can be used for monitoring and performance analysis on Linux systems. Some popular options include:

• top - This is a command-line utility that shows real-time information about the processes running on a Linux system, such as their CPU and memory usage.
• htop - This is a more advanced version of top that provides a more user-friendly interface and additional features, such as the ability to sort processes by different metrics and to kill processes.
• sar - This is a command-line utility that collects and displays performance metrics for a Linux system over time. It can be used to analyze CPU, memory, I/O, and network usage, as well as other metrics.
• iostat - This is a command-line utility that shows real-time information about I/O performance on a Linux system. It can be used to monitor the performance of disks and other storage devices.
• vmstat - This is a command-line utility that shows real-time information about various system resources, such as memory, CPU, and I/O. It can be used to monitor the overall health of a Linux system.
• netstat - This is a command-line utility that shows information about network connections on a Linux system. It can be used to monitor the status of network connections and to diagnose networking issues.

There are also many modern monitoring tools and software programs available for Linux, such as Prometheus and Zabbix. These tools typically offer more advanced features and capabilities than the built-in Linux utilities, such as the ability to collect and store metrics over time, and to generate alerts when certain conditions are met.

To run your own email server using Linux and other open source software, you’ll need to first choose a Linux distribution and install it on your server. I’d go with either Ubuntu, Debian or Rocky Linux. Once you’ve done that, you can choose an email server software that is compatible with Linux, such as Postfix or Exim. After installing and configuring the email server software, you’ll need to set up DNS records and configure authentication and encryption to ensure that your email server is secure. Finally, you’ll need to test your email server to make sure it is working properly and can send and receive messages.

Definition

A load balancer is a type of software or hardware that distributes incoming traffic across multiple servers or resources. This allows the load balancer to distribute the workload evenly, improving the performance and availability of the application.

The Load Balancer Lab

To run your own load balancer using open source software, you will need to:

• Install and configure the load balancer software on a server. Some popular open source options include HAProxy, Nginx, and Envoy.
• Configure the load balancer to distribute incoming traffic to the appropriate servers or resources. This typically involves setting up virtual servers and defining rules for routing traffic.
• Test the load balancer to ensure that it is working correctly and distributing traffic as expected.
• Monitor the load balancer and the underlying servers to ensure that the system is performing well and handling traffic effectively.
• Continually tune and optimize the load balancer configuration to improve performance and ensure that the application is always available and responsive.

Your web applications need a solution to store and retrieve its data. A relational database is often used in web applications. MySQL, MariaDB and PostgreSQL are some popular relational databases. There’s also SQLite. Many applications can use any of these relational databases by the virtue of the database layer abstraction. If you are writing your own web application, pick any one database and install it on your web server.

Install The Database

• Install the package.
• Enable and start the database systemd unit.
• Initialize the database server.
• Create databases.
• Create database users and set their passwords.

Connect The Web Application To The Database Server

As soon as you are ready to deploy services and applications on the Internet, the first thing you need is a registered domain and a DNS server. Often people just use the DNS service provided by the domain registrar or the hosting or cloud provider. Using the managed service is not a requirement. You can host your own DNS server and manage the DNS for your domains. There are many open source software using which you can build your own DNS servers. Bind is the traditional and probably the most popular DNS solution out there. There are other options such as Knot, PowerDNS and Unbound.