Beats (Filebeat, Metricbeat) in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Filebeat configuration snippet?

Given this Filebeat input configuration, what will Filebeat do when started?

Elasticsearch

filebeat.inputs:
- type: log
  enabled: true
  paths:
    - /var/log/syslog
  multiline.pattern: '^\['
  multiline.negate: true
  multiline.match: after

A Filebeat reads /var/log/syslog and combines lines not starting with '[' into the previous line

B Filebeat reads /var/log/syslog and combines lines starting with '[' into the previous line

C Filebeat reads /var/log/syslog but does not combine any lines because multiline is disabled

D Filebeat reads /var/log/syslog and combines all lines into a single event

💡 Hint

Look at multiline.negate and multiline.match values carefully.

The multiline.pattern '^\[' matches lines starting with '['. With multiline.negate: true and multiline.match: after, lines NOT starting with '[' are appended to the previous line, combining multiline messages correctly.

❓ Predict Output

intermediate

What metric does Metricbeat collect with this module config?

Given this Metricbeat module configuration, what metric will be collected?

Elasticsearch

metricbeat.modules:
- module: system
  metricsets:
    - cpu
    - memory
  period: 10s
  enabled: true

A CPU and memory usage metrics every 10 seconds

B Only CPU usage metrics every 10 seconds

C Only memory usage metrics every 10 seconds

D Disk usage metrics every 10 seconds

💡 Hint

Check the metricsets list carefully.

The configuration enables the system module with cpu and memory metricsets, so both CPU and memory metrics are collected every 10 seconds.

🔧 Debug

advanced

Why does Filebeat fail to start with this config?

This Filebeat config snippet causes Filebeat to fail on startup. What is the cause?

Elasticsearch

filebeat.inputs:
- type: log
  enabled: true
  paths: /var/log/*.log
output.elasticsearch:
  hosts: ["localhost:9200"]

A enabled must be false to start Filebeat

B paths should be a list, not a string

C output.elasticsearch hosts must be a string, not a list

D type: log is invalid, should be type: file

💡 Hint

Check the YAML syntax for paths.

The paths field expects a list of strings, but here it is given as a single string, causing a config error.

❓ Predict Output

advanced

What is the output of this Metricbeat processor configuration?

Given this Metricbeat config snippet, what will be the value of the 'host.name' field in the event?

Elasticsearch

processors:
- add_host_metadata:
    netinfo.enabled: false
- add_cloud_metadata:
- add_fields:
    target: host
    fields:
      name: custom-hostname

A The cloud provider hostname

B The system hostname from the OS

C An empty string

D "custom-hostname"

💡 Hint

Look at the add_fields processor target and fields.

The add_fields processor adds a 'name' field under 'host' with value 'custom-hostname', overriding default host.name.

🧠 Conceptual

expert

Which option best describes the role of Filebeat and Metricbeat in the Elastic Stack?

Choose the most accurate description of Filebeat and Metricbeat roles.

A Both Filebeat and Metricbeat collect logs but from different sources

B Filebeat collects metrics; Metricbeat collects logs

C Filebeat collects and ships log files; Metricbeat collects and ships system and service metrics

D Filebeat and Metricbeat are used to store data in Elasticsearch

💡 Hint

Think about what logs and metrics mean.

Filebeat is designed to collect and ship log files, while Metricbeat collects system and service metrics. They do not store data themselves; Elasticsearch stores data.

Practice

1. What is the primary purpose of Filebeat in the Elastic Stack?

easy

A. To visualize data in dashboards

B. To collect system metrics like CPU and memory usage

C. To collect and ship log files from servers

D. To store data in Elasticsearch

Solution

1. Step 1: Understand Filebeat's role

   Filebeat is designed to collect log files from servers and forward them.

2. Step 2: Differentiate from Metricbeat

   Metricbeat collects system metrics, not logs.

3. Final Answer:

   To collect and ship log files from servers -> Option C

4. Quick Check:

   Filebeat = log collection [OK]

Hint: Filebeat = logs, Metricbeat = metrics [OK]

Common Mistakes:

• Confusing Filebeat with Metricbeat
• Thinking Filebeat visualizes data
• Assuming Filebeat stores data

2. Which of the following is the correct syntax to start Filebeat on a Linux system?

easy

A. sudo systemctl start filebeat

B. filebeat run start

C. start filebeat service

D. service filebeat enable

Solution

1. Step 1: Identify standard Linux service start command

   On modern Linux systems, services are started with 'sudo systemctl start servicename'.

2. Step 2: Match with Filebeat service

   Filebeat service is named 'filebeat', so the command is 'sudo systemctl start filebeat'.

3. Final Answer:

   sudo systemctl start filebeat -> Option A

4. Quick Check:

   systemctl start filebeat = correct syntax [OK]

Hint: Use systemctl to manage services on Linux [OK]

Common Mistakes:

• Using incorrect command order
• Confusing 'start' with 'enable'
• Using non-standard service commands

3. Given this Filebeat configuration snippet:

filebeat.inputs:
- type: log
  paths:
    - /var/log/syslog
output.elasticsearch:
  hosts: ["localhost:9200"]

What will Filebeat do when started?

medium

A. Store logs locally without sending

B. Collect system metrics and send to Elasticsearch

C. Send logs to a remote Logstash server

D. Collect logs from /var/log/syslog and send to Elasticsearch at localhost:9200

Solution

1. Step 1: Analyze input configuration

   The input type is 'log' and path is '/var/log/syslog', so Filebeat collects logs from this file.

2. Step 2: Analyze output configuration

   Output is set to Elasticsearch at 'localhost:9200', so logs are sent there.

3. Final Answer:

   Collect logs from /var/log/syslog and send to Elasticsearch at localhost:9200 -> Option D

4. Quick Check:

   Input logs + output Elasticsearch = Collect logs from /var/log/syslog and send to Elasticsearch at localhost:9200 [OK]

Hint: Check input type and output host to predict behavior [OK]

Common Mistakes:

• Confusing logs with metrics
• Assuming output is Logstash
• Ignoring the paths setting

4. You configured Metricbeat to collect CPU metrics but see no data in Elasticsearch. Which of these is a likely cause?

medium

A. Metricbeat service is not running

B. Filebeat is collecting logs instead of metrics

C. Elasticsearch is not installed

D. Metricbeat configuration file is empty

Solution

1. Step 1: Check Metricbeat service status

   If Metricbeat is not running, it cannot collect or send metrics.

2. Step 2: Consider other options

   Filebeat collecting logs is unrelated; Elasticsearch not installed would cause errors; empty config would cause no collection.

3. Final Answer:

   Metricbeat service is not running -> Option A

4. Quick Check:

   Service running = data sent [OK]

Hint: Always verify Metricbeat service is active [OK]

Common Mistakes:

• Mixing Filebeat and Metricbeat roles
• Ignoring service status
• Assuming Elasticsearch absence without error

5. You want to monitor both system logs and CPU metrics on a server using Beats. Which setup is best?

hard

A. Run Filebeat and Metricbeat but send data to different Elasticsearch clusters

B. Run Filebeat for logs and Metricbeat for CPU metrics, both sending to Elasticsearch

C. Run Metricbeat for logs and Filebeat for metrics

D. Run only Filebeat configured for logs and metrics

Solution

1. Step 1: Identify Beats roles

   Filebeat collects logs; Metricbeat collects system metrics like CPU.

2. Step 2: Choose correct combination

   Running both Beats with their proper roles and sending data to the same Elasticsearch cluster is best for unified monitoring.

3. Final Answer:

   Run Filebeat for logs and Metricbeat for CPU metrics, both sending to Elasticsearch -> Option B

4. Quick Check:

   Filebeat = logs + Metricbeat = metrics [OK]

Hint: Use Filebeat for logs and Metricbeat for metrics together [OK]

Common Mistakes:

• Mixing roles of Filebeat and Metricbeat
• Sending data to separate clusters unnecessarily
• Assuming one Beat can do both well