We will need a Zabbix server capable of performing monitoring, with the following requirements:

• A server with Zabbix server installed on a Linux distribution of your choice, such as CentOS or Ubuntu, but a distribution such as Debian or anything else will suit you just as well
• MariaDB set up to work with your Zabbix server
• NGINX or Apache set up to serve the Zabbix frontend

I'll be using the same server as we used in the previous chapter, but any Zabbix server should do.

With the release of Zabbix 5, Zabbix also officially started support for the new Zabbix agent 2. Zabbix agent 2 brings some major improvements and is even written in another coding language, which is Golang instead of C. In this recipe, we will be exploring how to work with Zabbix agent 2 and explore some of the new features introduced by it.

You'll also need a Linux distribution of your choice running Zabbix agent 2.

Getting ready

To get started with Zabbix agent 2, all we need to do is install it to a (Linux) host that we want to monitor. Make sure you have an empty Linux (CentOS 8) host ready to monitor.

How to do it

Let's see how to install Zabbix agent 2 and then move on to actually working with it.

Installing Zabbix agent 2

Let's start by installing Zabbix agent 2 on the Linux host we want to monitor. I'll be using a CentOS 8 machine:

1. Issue the following command to add the repository:

   For RHEL-based systems:

   rpm -Uvh https://repo.zabbix.com/zabbix/5.0/rhel/8/x86_64/zabbix-release-5.0-1.el8.noarch.rpm

   For Debian-based systems:

   wget https://repo.zabbix.com/zabbix/5.0/debian/pool/main/z/zabbix-release/zabbix-release_5.0-1+buster_all.deb
   dpkg -i zabbix-release_5.0-1+buster_all.deb

2. Then issue the following command to install Zabbix Agent 2:

   For RHEL-based systems:

   dnf install zabbix-agent2

   For Debian-based systems:

   apt install zabbix-agent2

Congratulations, Zabbix agent 2 is now installed and ready to use.

Using a Zabbix agent in Passive mode

Let's start by building a Zabbix agent with passive checks:

1. After installing Zabbix agent 2, let's open the Zabbix agent configuration file for editing:

   vim /etc/zabbix/zabbix_agent2.conf

   In this file, we edit all the Zabbix agent configuration values we could need from the server side.

2. Let's start by editing the following values:

   Server=127.0.0.1
   Hostname=Zabbix server

3. Change Server to the IP of the Zabbix server that will monitor this passive agent. Change Hostname to the hostname of the monitored server.
4. Now restart the Zabbix agent 2 process:

   systemctl restart zabbix-agent2.service

5. Now move to the frontend of your Zabbix server and add this host for monitoring.
6. Go to Configuration | Hosts in your Zabbix frontend and click Create host in the top-right corner.
7. To create this host in our Zabbix server, we need to fill in the values seen in the following screenshot:
   

   Figure 2.1 – The Zabbix host creation page for host lar-book-agent

   It's important to add the following:

   • Host name: To identify this host.
   • Groups: To logically group hosts.
   • Interfaces: To monitor this host on a specific interface. No interface means no communication.
8. It is also important to add a template to this host. As this is a Linux server monitored by a Zabbix agent, let's add the correct out-of-the-box template as shown in the following screenshot:
   

   Figure 2.2 – The Zabbix host template page for host lar-book-agent

9. Click the Add button and you're done creating this agent host. Now that you've got this host, make sure the ZBX icon turns green, indicating that this host is up and being monitored with the passive Zabbix agent:
   

   Figure 2.3 – The Zabbix configuration hosts page, host lar-book-agent

10. You can now see the values received on this host by going to Monitoring | Hosts and checking the Latest data button. Please note that the values could take a while to show up:

Figure 2.4 – The Zabbix latest data page for host lar-book-agent

Using a Zabbix agent in Active mode

Now let's check out how to configure the Zabbix agent with active checks. We need to change some values on the monitored Linux server host side:

1. Start by executing the following command:

   vim /etc/zabbix/zabbix_agent2.conf

2. Now let's edit the following value to change this host to an active agent:

   ServerActive=127.0.0.1

3. Change ServerActive to the IP of the Zabbix server that will monitor this passive agent and also change Hostname to lar-book-agent:

   Hostname=lar-book-agent

4. Now restart the Zabbix agent 2 process:

   systemctl restart zabbix-agent2.service

5. Now move to the frontend of your Zabbix server and let's add another host with a template to do active checks instead of passive ones.
6. First, let's rename our passive host. To do that, go to Configuration | Hosts in your Zabbix frontend and click the host we just created. Change Host name as follows:
   

   Figure 2.5 – The Zabbix host configuration page for host lar-book-agent_passive

   We are doing this because for an active Zabbix agent, the hostname in the file needs to match our Zabbix server.

7. Go to Configuration | Hosts in your Zabbix frontend and click Create host in the top-right corner.
8. Now let's create the host as follows:
   

   Figure 2.6 – The Zabbix host configuration page for host lar-book-agent

9. Also, make sure to add the correct template, named Template OS Linux by Zabbix agent active:

Figure 2.7 – The Zabbix host template page for host lar-book-agent

Please note that the ZBX icon won't turn green for an active agent. But when we navigate to Monitoring | Hosts and check Latest data, we can see our active data coming in.

Tip

As you might have noticed just now, a Zabbix agent can run in both passive and active mode. Keep this in mind when creating your Zabbix agent templates, as you might want to combine the check types.

How it works…

Now that we have configured our Zabbix agents and know how they should be set up, let's see how the different modes work.

Passive agent

The passive agent works by collecting data from our host with the Zabbix agent. Every time an item on our host reaches its interval, the Zabbix server asks the Zabbix agent what the value is now:

Figure 2.8 – Communication diagram between server and passive agent

Active agent

The active agent works by sending data from the Zabbix agent to Zabbix server. Every time an item on our agent reaches its update interval, the agent will send the value to our server. We can also use this to send a notification to our server faster when something goes wrong:

Figure 2.9 – Communication diagram between server and active agent

As mentioned, we can use both types of checks at the same time, giving us the freedom to configure every type of check we could possibly need. Our setup would then look like this:

Figure 2.10 – Communication diagram between server and both agent types

See also

There's a lot of new stuff going on under the hood of Zabbix agent 2; if you're interested in learning more about the core of Zabbix agent 2, check out this cool blog post by Alexey Petrov: https://blog.zabbix.com/magic-of-new-zabbix-agent/8460/.