1 Exemplos de uso

Visão geral

Esta seção fornece exemplos de uso das etapas de pré-processamento para realização de algumas tarefas práticas.

Filtragem de registros de log de eventos do VMware

Usando uma expressão regular para pré-processamento e filtrar eventos desnecessários do log de eventos do VMware.

1. No host VMware Hypervisor em funcionamento, verifique se o item de log de eventos vmware.eventlog[<url>,<mode>] está presente e funcionando corretamente. Observe que o item de log de eventos já pode estar presente no hypervisor se o Template VM VMware tiver sido vinculado durante a criação do host.

2. No host VMware Hypervisor, crie um item dependente dependent item do tipo 'Log' e defina o item de log de eventos como seu mestre.

Na aba "Preprocessing" do item dependente, selecione a opção de validação "Correspondências com expressão regular" e preencha o padrão, por exemplo:

".* logged in .*" - filters all logging events in the event log
       "\bUser\s+\K\S+" -  filter only lines with usernames from the event log

Outra abordagem que permite o uso de grupos de correspondência e controle de saída é selecionar a opção "Expressão regular" na aba "Pré-processamento" e preencher os parâmetros, por exemplo:

pattern: ".*logged in.*", output: "\0" - filters all logging events in the event log
       pattern "User (.*?)(?=\ )", output: "\1" - filter only usernames from the event log

Checking retrieved value type

This example uses the Custom multiplier preprocessing step to check if the retrieved item value type is numeric.

In the Preprocessing tab of an item, select the "Custom multiplier" preprocessing step and set the following parameter:

# Multiplies the retrieved value by 1:
       number: 1

Checking for not supported value

This example uses the Check for not supported value preprocessing step to check if the item value could not be retrieved.

When a Zabbix server/proxy poller process attempts to collect an item value, it may:

• Return a valid result.
• Return a result that initially seems valid but may become unsupported later (e.g., due to a value type mismatch after preprocessing).
• Return an error of collecting the value, causing the item to become unsupported. Common causes include:
  • Unknown item key (for Zabbix agent, Simple check, or Zabbix internal items)
  • Unknown OID (SNMP agent), unknown sensor (IPMI agent), or no JMX metric (JMX agent)
  • Cannot read trap file (SNMP trap)
  • Script not found (External check)
  • No such URL (HTTP agent)
  • Login failed (SSH agent, TELNET agent)
  • Invalid formula syntax (Calculated), JavaScript syntax error (Script), or invalid SQL (Database monitor)

To detect and handle errors of collecting item values, you can use the "Check for not supported value" preprocessing step. Note that this step is always executed first and only detects errors that occur before preprocessing begins.

In the Preprocessing tab of an item, select the "Check for not supported value" preprocessing step.

Then, use the Custom on fail option to discard the value (in this case, the error), set a custom value, or return a custom error message. Please note that discarded values are not stored in the database; as a result, triggers are not evaluated and trend data is not generated.