In this chapter, we learned about a number of features in Zabbix that allow automatic configuration, creation, and maintenance:

• Low-level discovery or LLD
• Network discovery
• Active agent auto-registration

LLD allows entities to be discovered  by using Zabbix agents—it has built-in support for network interfaces, filesystems, and CPUs. We talked about customizing thresholds and other values per discovered entity with user macro context support. Zabbix can also discover SNMP tables, such as network interfaces, but it is not limited to that—any SNMP table can be discovered. We also looked at creating custom discoveries, including MySQL database discovery.

LLD offers a way to filter results by regular expressions, and we checked out how global regular expressions can make that easier here and also in other places, such as log monitoring.

After that, we explored network discovery, which is all about scanning an address range and automatically adding hosts, potentially linking them to proper templates, and then adding them to host groups.

In the other direction, there's active agent auto-registration, where active agents can chime in and the server starts monitoring them automatically. Metadata support for this feature allows quite fine-grained rules on what templates to link in or what host groups the hosts should belong to. We noted that, if not used, active checks should be disabled on agents; otherwise, an unnecessary load would be placed on the entire Zabbix infrastructure.

In the next chapter, we will explore the built-in web monitoring feature. It allows us to define scenarios that consist of steps. Steps check a page and may look for a specific HTTP response code or string in the returned page. We will also try out logging in to applications and extracting data from one page and then passing it to another.