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Log router

As explained in Cloud Observability in Action

A log router is software that receives, processes, and forwards log records between sources and destinations.

A log router collects log records from system and application sources, optionally processes or prunes them, and forwards them to a central destination for search and analysis. Log forwarding, collection, and aggregation are treated as closely related operational roles. section 4.1 section 2.3.3

Typical inputs and selection concerns include:

  • System logs from operating systems, Kubernetes control planes and worker nodes, user activity, API usage, and infrastructure automation. section 4.1
  • Application logs emitted by code; standardizing agents where possible reduces patching and upgrade work. section 4.1
  • Runtime footprint, ingestion throughput, delivery reliability, encryption, multitenancy, and ingestion cost shape agent selection. section 2.3.3
  • Sampling or filtering, such as dropping production DEBUG records, can reduce downstream volume and storage costs. section 2.3.3

Containerized routing pipeline

A Docker Compose setup sends ho11y container logs through Fluentd to Fluent Bit, which forwards them to OpenSearch; OpenSearch Dashboards then supports querying and visualization. Fluentd offers a larger plugin ecosystem, while lightweight Fluent Bit suits constrained environments. section 4.1.1

Listing 4.4 Fluent Bit configuration
[INPUT]
    Name forward            #1
    Listen 0.0.0.0          #2
    Port 24224              #3
 
[OUTPUT]
    Name opensearch         #4
    Match **                #5
    Host opensearch-node1   #6
    Port 9200
    Index ho11y             #7
    Suppress_Type_Name on   #8

The configuration shows the router accepting Forward input and matching records to an OpenSearch output. section 4.1.1

How Cloud Observability in Action covers it

How deep it goes
Explains sources, trade-offs, pruning, alternatives, and a Docker Compose implementation, but stops short of exhaustive configuration.
Examples
Uses ho11y, Docker Compose, Fluentd, Fluent Bit, OpenSearch, OpenSearch Dashboards, sampling, and production DEBUG filtering.
What it assumes
Assumes basic awareness of system, application, and centralized logs while introducing their sources and routing roles.
What you can do after
Build a containerized routing pipeline and evaluate agents by footprint, throughput, reliability, security, plugins, and cost.
How it connects
Connects log routers with system logs, application logs, Kubernetes, OpenTelemetry, Fluent Bit, Fluentd, Logstash, and centralized log storage.

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This explainer was generated by Manning's knowledge graph from the text of Cloud Observability in Action. The section links point to the parts of the book it draws on.