Tag Routing: Detecting Unmatched INPUT Tags That Silently Drop Logs

Problem/Feature Description

An SRE team has been investigating a "missing logs" incident in production. Their Kubernetes logging pipeline appeared healthy — Fluent Bit was running, no errors in the Fluent Bit pod logs — but application logs from their payment service were simply not appearing in their log aggregation backend. After two hours of debugging, they suspect a tag routing misconfiguration.

Validate the Fluent Bit configuration below with a focus on tag routing. Trace every INPUT tag through all FILTER and OUTPUT Match patterns. Identify any INPUT tags that are not covered by an OUTPUT Match, any FILTER Match patterns that do not correspond to INPUT tags, and any orphaned sections. Produce a corrected configuration and a routing analysis report.

Output Specification

Produce:

• A corrected fluent-bit.conf with tag routing issues fixed
• A routing-report.md that: (1) shows the complete tag flow for each INPUT, (2) identifies each routing gap, and (3) explains the real-world consequence of each gap (e.g., which service's logs would be dropped)

Input Files

The following file is provided as input.

=============== FILE: inputs/fluent-bit.conf =============== [SERVICE] Flush 5 Daemon Off Log_Level info HTTP_Server On HTTP_Listen 0.0.0.0 HTTP_Port 2020

[INPUT] Name tail Tag kube.app.* Path /var/log/containers/default.log Exclude_Path /var/log/containers/fluent-bit.log Parser docker Mem_Buf_Limit 50MB DB /var/log/flb_kube.db

[INPUT] Name tail Tag kube.payment.* Path /var/log/containers/payment.log Exclude_Path /var/log/containers/fluent-bit.log Parser docker Mem_Buf_Limit 50MB DB /var/log/flb_payment.db

[INPUT] Name systemd Tag host.systemd Systemd_Filter _SYSTEMD_UNIT=kubelet.service Read_From_Tail On

[FILTER] Name kubernetes Match kube.app.* Kube_URL https://kubernetes.default.svc:443 Merge_Log On

[FILTER] Name grep Match kube.payment.* Regex log ERROR|WARN

[OUTPUT] Name es Match kube.app.* Host elasticsearch.logging.svc Port 9200 Index app-logs tls On tls.verify On

[OUTPUT] Name es Match kube.infra.* Host elasticsearch.logging.svc Port 9200 Index infra-logs tls On tls.verify On