Nagios vs Zabbix vs Prometheus: The Key Differences to Know

Nagios, Zabbix, and Prometheus are infrastructure monitoring solutions that can monitor the status of your servers, networks, cloud services, virtual machines, and so on. In this article, we will compare their strengths and functionalities and find out which one is more suitable for you. Before proceeding, here is a brief overview of each product:

Nagios Core is a free and open-source application that can monitor your servers and services and alert you when something goes wrong. It is written by Ethan Galstad and a group of developers as a program for monitoring Linux systems, but it can be installed on other Unix variants.

Zabbix is another open-source software designed primarily for monitoring IT infrastructures. It was first released in 2004 and is still being actively developed with new releases every six months.

Lastly, Prometheus is a server monitoring tool that can collect time series data from your server and compile them into graphs. It was originally created by SoundCloud, and it is now an open-source project hosted on GitHub.

In this article, we are going to perform a side-by-side comparison of Nagios, Zabbix, Prometheus so you can make an informed decision on which to use in your organization. The comparison will be based on the following criteria:

1. Functionality Overview
2. Easy installation and deployment
3. Metrics collection
4. Architecture
5. Compatible platforms
6. Scalability
7. Data visualization
8. Incident management and alerting
9. UI & UX design
10. Documentation and support
11. Pricing

1. Overview

✖ - does not support

✔ - partial support

✔✔ - full support

✔✔✔ - excellent support

2. Installation and deployment: Prometheus > Nagios > Zabbix

Since all three tools are open-source, you are able to self-host them on your server.

Nagios Core offers a step-by-step installation guide which describes how to get started with setting it up. The installation process takes about 10 minutes, and you also need to install and configure the Apache server and Nagios Plugins for Nagios Core to function correctly. If you don't want to take time to self-host, Nagios also offers a commercial product for the enterprise called Nagios XI.

Zabbix also has an installation guide on their website which allows you to choose the Zabbix version, the OS distribution and version, the Zabbix component, the database as well as the web server. However, the guide does not specify how to install and set up the database and web server, so you'll have to do it independently.

Prometheus is the easiest one to install and deploy, as it has compiled everything together and does not require external data storage. All you have to do is download the latest release from linked web page, and execute the prometheus binary. And as a result, Prometheus wins this round.

3. Metrics collection: Prometheus > Zabbix > Nagios

The three tools use different strategies when it comes to data collection.

First of all, Nagios requires different plugins when monitoring different services. For instance, you need NRPE to obtain data such as CPU load, memory usage, and disk usage from the host. Once you've set up the plugin and the host you wish to monitor, the collected data should be accessible through the Nagios interface. However, you cannot do much customization here; unfortunately, there is no graphical way to create configurations. You have to place the related directives in an object configuration file.

Zabbix, on the other hand, uses item key format to retrieve information. For example, an item with the key name system.cpu.load will gather data of the CPU load. You can customize the result by specifying additional parameters. For example, system.cpu.load[avg5] will return CPU load average for the last 5 minutes.

Lastly, Prometheus has the most powerful metrics collection functionality among the three. It uses PromQL, Prometheus's unique and powerful query language, to retrieve and aggregate time-series data from a multidimensional data model in real-time. The queried data can then be displayed as a graph or table, or sent to external systems via HTTP protocols. Therefore, Prometheus wins metrics collection.

4. Architecture: tie

Nagios uses a host-agent architecture in which the Nagios server (host) is installed on the monitoring server, and plugins (agent) are installed on the monitored server. The agents will periodically collect data from the server and send it to the host.

Zabbix also has a host-agent architecture. However, it is slightly more complicated compared to Nagios, as it requires external data storage, such as MySQL or PostgreSQL. The database should be installed on the host server.

Prometheus has the simplest architecture among the three as you can configure it to send or receive data. The instance sending data will be the agent, and the one receiving data will be the host.

Overall, even though these platforms have slightly different architectures, we can't say one is better than the other.

5. Compatible Platforms: Prometheus > Zabbix/Nagios

Nagios is designed to run on Linux operating systems, but it can monitor Linux, Windows and Unix operating systems with the right plugins.

Zabbix's compatible operating system is listed in the installation guide we introduced before. One thing to note is that Zabbix can only be installed on LTS (Long-Term-Support) versions of your system distros, if it has one.

Lastly, Prometheus can operate on Linux, macOS, and Windows.

As a result, Prometheus wins this round for being compatible with most operating systems.

6. Scalability: Prometheus/Zabbix > Nagios

As we've mentioned before, all three tools use host-agent architecture or similar, which means all of them can be scaled to meet demands. However, they don't always perform well even though scaling is possible.

For instance, since Nagios requires the user to input configurations in a text file, and Zabbix requires you to set up external databases, they are going to require significantly more effort when it comes to scaling.

Also, Nagios still needs to catch up with the IT infrastructure today. Many companies and organizations find themselves having to create multiple Nagios servers for different groups of infrastructure (agent) when a single server cannot handle the load, which introduces the downside of unable to view your entire infrastructure in one place.

Zabbix faces similar issues. However, there is a workaround called Zabbix proxy. The proxy will act as the middleman between the host and the agent. It will collect and pre-process data transmitted from the agent on behalf of the Zabbix server, hence taking the load off of the host.

As for Prometheus, there is a tool called Federation, which allows one Prometheus server to retrieve data from another Prometheus server through the /federate endpoint.

For this round, only Nagios loses since Zabbix and Prometheus both offer scaling solutions that can accommodate modern IT demands.

7. Data visualization: Zabbix > Prometheus/Nagios

Nagios does not come with data visualization function built-in, but it can be added using the NagVis plugin. The plugin allows you to create maps for visualizing the relationships between different hosts and services so that when a problem occurs, you will be able to tell which components are affected.

In comparison, Zabbix comes with much better chart and dashboard creation abilities. For example, it allows you to create custom charts by adding filters and constraints, aggregate multiple items into one chart, or create network maps displaying the status of your entire infrastructure.

Zabbix also allows you to create dashboards by putting multiple views together, allowing you to keep track of your entire organization.

On the other hand, Prometheus does not have impressive visualization ability. It only allows you to check one graph at a time using its expression browser. There is no way to create dashboards or customize the graphs in any way.

Overall, Zabbix has the best data visualization functionality among the three.

8. Incident management and alerting: Zabbix > Prometheus > Nagios

Nagios is capable of pushing notifications to selected users when an incident occurs. However, it does not provide a user interface for this purpose so you must input the alert rules in a text file. Also, as Nagios simply executes the predefined command when an incident occurs, it cannot guarantee delivery of the notification.

Zabbix's alerting functionality is much easier to use in comparison. First of all, there is a graphical interface that allows you to define notification methods such as email, SMS, or webhook. You can also define custom scripts that will execute when an incident occurs.

Zabbix also allows you to create threshold-based conditions that will trigger the alert. You can also define an escalation mechanism. For instance, when an incident occurs, you can choose to get an email first and then a text if the issue isn't resolved within 30 minutes. Furthermore, if it remains unresolved after an hour, you can escalate by configuring Zabbix to call the relevant manager.

Prometheus also has an alerting mechanism similar to Zabbix. However, you need to install the Alertmanager, which is a separate package. Afterward, you'll be able to create alert rules, notification methods, and so on. Prometheus also doesn't have a graphical interface either when it comes to defining alerts, but its official documentation provides a few notification templates to make the process a lot easier.

For this round, Zabbix has the best incident management solution overall, Prometheus come second, and Nagios' alerting functionality needs to be updated.

9. UI & UX design: Zabbix > Prometheus > Nagios

As for the UI and UX design, Zabbix is the clear winner.

Nagios' interface looks outdated as it hasn't been updated for a long time. You may navigate through its different pages using the links on the left side of the interface, but many key features lack a graphical interface as we've mentioned before.

Prometheus' UI design is a bit better. However, it is too simple and lacks many key features such as a dashboard and a graphical configuration page.

Zabbix's design is better in comparison, but it is not without issues. For example, the navigation design is a bit too complex, and the generated charts are not interactive.

10. Documentation and support: Prometheus > Zabbix > Nagios

All three platforms offer great documentation and support. However, in comparison, Prometheus has the largest community support, with 45.5k stars on GitHub at the time of writing. Its documentation also has a better structure, and it includes not only the basics of Prometheus but also best practices, real-life guides, as well as a complete tutorial that walks through common use cases.

Zabbix has the second-best documentation among the three. But even though it is very detailed and well-written, it is missing some real-life examples that many users would like.

Nagios' documentation is also very detailed, but it is not as easy to navigate as the other two.

11. Pricing: tie

Last but not least, let's compare their prices. All three tools are open-source and free to install on your own server, but Zabbix does charge you for their technical support.

Nagios offers a commercial product, Nagios XI that provides additional functionality not found in the free version such as better visualization, better user management, and a graphical interface for adding configurations.

The ultimate alerting setup: Better Uptime + Prometheus/Zabbix

While these three tools have their strengths, incident management and alerting are not one of them. If you are looking for something more intuitive than what each one provides, take a look at Better Uptime. It is a hosted monitoring and incident management platform that can monitor your entire infrastructure and alert you appropriately if something goes wrong.

You can get started by creating an uptime monitor for your application. If downtime is detected, Better Uptime can notify you through a variety of channels such as call, SMS, email, push notifications, and more.

Several integrations are also provided for you to easily get it working with your existing infrastructure. For example, you can replace Prometheus' Alertmanager with Better Uptime by locating its configuration file and replacing its content with the sample provided on the instruction page. Zabbix integration is also available.

You can also define an escalation policy as you see fit.

Conclusion

Nagios, Zabbix, and Prometheus are all popular IT infrastructure monitoring solutions. However, Nagios Core lacks many significant features present in Zabbix and Prometheus, unless you are willing to pay for the commercial version (Nagios XI).

Zabbix and Prometheus are both excellent platforms but have different strengths. Prometheus is easier to set up, and it is better at data collection due to its powerful query language (PromQL). It also has a significantly larger community where you'll be able to get support while configuring it to meet your needs.

When it comes to data visualization, Zabbix has the clear upper hand. Unlike Prometheus, you can create charts, maps, and dashboards without relying on third-party services such as Grafana. Zabbix also has a better-designed user interface, a better user management solution, and a better alerting functionality.

It is difficult to say which one is better than the other as it depends entirely on your needs. If you want a one-stop monitoring solution, and don't mind the tedious installation process, you should go with Zabbix. If you want a more robust data collection functionality, and don't mind using third-party tools such as Grafana and Better Uptime, you should choose Prometheus instead.

Article by

Eric Hu

Eric is a technical writer with a passion for writing and coding, mainly in Python and PHP. He loves transforming complex technical concepts into accessible content, solidifying understanding while sharing his own perspective. He wishes his content can be of assistance to as many people as possible.

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