Access Log Middleware

The Access Log Middleware (accessLog) enables you to enrich access logs with custom request attributes such as headers, query parameters, cookies, and other contextual data. This helps improve observability, traceability, and debugging across your services.

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Overview

By default, access logs typically contain basic information such as request method, path, status code, and response time. The accessLog middleware allows you to extend those logs with additional request-level data that is critical for:

• Debugging production issues
• Tracking client behavior
• Correlating requests across systems
• Enhancing security and audit logging
• Improving monitoring and analytics

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Basic Configuration

- name: custom-logger
  type: accessLog
  paths:
    - "/.*"
  rule:
    headers:
      - CF-IPCountry
    query:
      - debug
      - source
    cookies:
      - session_id

This configuration logs:

• The CF-IPCountry request header (useful for geo-location)
• The debug and source query parameters
• The session_id cookie value

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Supported Log Fields

The middleware can extract values from multiple parts of the incoming request.

Headers

rule:
  headers:
    - X-Request-ID
    - User-Agent

Logs the specified HTTP request headers.

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Query Parameters

rule:
  query:
    - page
    - limit

Logs values from the request query string.

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Cookies

rule:
  cookies:
    - session_id
    - auth_token

Logs selected cookies for traceability or session analysis.

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Path-Based Logging

You can limit logging enrichment to specific paths:

paths:
  - /api/*
  - /admin/*

This helps reduce log noise and control sensitive data exposure.

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Log Output Behavior

• Missing fields are logged as empty or null values
• Values are captured at request time
• Fields are appended to existing access log entries
• The logging format depends on your gateway’s global log configuration

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Example: Observability-Focused Logging

- name: observability-logger
  type: accessLog
  paths:
    - /api/*
  rule:
    headers:
      - X-Request-ID
      - User-Agent
      - CF-IPCountry
    query:
      - version
    cookies:
      - session_id