Log Collectors Comparison Quiz
Test your understanding of log collectors (FluentBit, Promtail, Alloy, OTEL Collector).
Which of the following log collectors has the lowest memory usage?
- A) Promtail
- B) FluentBit
- C) Grafana Alloy
- D) OpenTelemetry Collector
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Answer: B) FluentBit
Explanation: FluentBit is written in C and has the lowest memory usage at approximately 10-50MB. The others are written in Go and use approximately 50-100MB of memory.
Which FluentBit FILTER adds Kubernetes metadata (namespace, pod_name, etc.) to logs?
- A) [FILTER] Name modify
- B) [FILTER] Name kubernetes
- C) [FILTER] Name parser
- D) [FILTER] Name record_modifier
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Answer: B) [FILTER] Name kubernetes
Explanation: FluentBit's kubernetes filter automatically adds metadata such as pod, namespace, and labels to logs through the Kubernetes API.
What is Promtail's main limitation?
- A) No JSON parsing support
- B) Cannot send to destinations other than Loki
- C) Cannot be used in Kubernetes environments
- D) Cannot handle multiline logs
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Answer: B) Cannot send to destinations other than Loki
Explanation: Promtail is designed as a dedicated agent for Grafana Loki and does not support sending to other destinations like OpenSearch or CloudWatch. If multiple destinations are needed, use FluentBit or OTEL Collector.
What configuration language does Grafana Alloy use?
- A) YAML
- B) JSON
- C) River (HCL-like)
- D) INI
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Answer: C) River (HCL-like)
Explanation: Grafana Alloy uses River, a configuration language similar to HCL (HashiCorp Configuration Language). It is more expressive than YAML and allows defining reusable components.
What is the order of pipeline components in OpenTelemetry Collector?
- A) Processors → Receivers → Exporters
- B) Receivers → Exporters → Processors
- C) Receivers → Processors → Exporters
- D) Exporters → Processors → Receivers
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Answer: C) Receivers → Processors → Exporters
Explanation: OTEL Collector pipelines are composed in the order: Receivers (receive data) → Processors (process/transform data) → Exporters (send data).
What scripting language can be used in FluentBit to implement complex log processing logic?
- A) Python
- B) JavaScript
- C) Lua
- D) Ruby
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Answer: C) Lua
Explanation: FluentBit supports Lua scripting to implement complex log processing logic (field transformation, conditional processing, sensitive data masking, etc.). Use the [FILTER] Name lua filter.
What pipeline_stages setting in Promtail configuration excludes specific logs?
- A) stage.filter
- B) stage.drop
- C) stage.exclude
- D) stage.ignore
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Answer: B) stage.drop
Explanation: Promtail's stage.drop excludes log lines matching regex or conditions. Example: Use expression: "healthcheck|readiness" to exclude healthcheck logs.
Which collector is most suitable when you need to send logs to both CloudWatch Logs and OpenSearch in AWS environments?
- A) Promtail
- B) FluentBit
- C) Grafana Alloy
- D) Logstash
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Answer: B) FluentBit
Explanation: FluentBit natively supports both cloudwatch_logs and opensearch output plugins. It can be easily deployed using the aws-for-fluent-bit image provided by AWS. Promtail and Alloy are optimized for Loki.
Which processor in OpenTelemetry Collector limits memory usage?
- A) batch
- B) memory_limiter
- C) resource
- D) filter
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Answer: B) memory_limiter
Explanation: The memory_limiter processor monitors OTEL Collector's memory usage and temporarily pauses data collection when the configured limit is reached to prevent OOM.
What is the recommended migration target when you need to also collect metrics and traces from an existing Promtail environment?
- A) FluentBit
- B) Logstash
- C) Grafana Alloy
- D) Filebeat
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Answer: C) Grafana Alloy
Explanation: Grafana Alloy is the successor project to Promtail, including all Promtail functionality while also being able to collect metrics (Prometheus) and traces (Tempo). Promtail configurations can be easily migrated to River syntax.