Router Access Log Fields Reference

This document provides a comprehensive reference for all fields available in Kthena Router access logs.

Overview

Kthena Router generates structured access logs for all AI inference requests. These logs provide detailed information about request processing, including timing breakdowns, routing decisions, token usage, and error information.

Log Format

Access logs are available in two formats:

• JSON: Structured JSON format suitable for log aggregation and analysis
• Text: Human-readable format for development and debugging

Text Format Structure

The text format follows this structure:

[timestamp] "METHOD /path PROTOCOL" status_code [error=type:message] model_name=name model_route=route model_server=server selected_pod=pod request_id=id tokens=input/output timings=total(req+upstream+resp)ms

Key features of the text format:

• Error placement: Error information appears immediately after the status code when present
• Timing format: Shows total time with breakdown in parentheses: timings=2350ms(45+2180+5)
• Compact representation: All information on a single line for easy parsing

Field Reference

Standard HTTP Fields

These fields follow the Envoy access log format for compatibility with existing log processing tools.

Field	Type	Description	Example
timestamp	string (RFC3339)	ISO 8601 timestamp when the request was received	2024-01-15T10:30:45.123Z
method	string	HTTP method used for the request	POST, GET
path	string	Request path including query parameters	/v1/chat/completions
protocol	string	HTTP protocol version	HTTP/1.1, HTTP/2
status_code	integer	HTTP response status code	200, 400, 500

Error Information

Error information is included when a request fails and appears immediately after the status code.

Field	Type	Description	Example
error.type	string	Error category or type	timeout, rate_limit, model_not_found
error.message	string	Detailed error message	Model inference timeout after 30s

Common Error Types

Error Type	Description	Typical Status Code
timeout	Request exceeded configured timeout	504
rate_limit	Request was rate limited	429
model_not_found	Requested model is not available	404
authentication_failed	Authentication credentials invalid	401
authorization_failed	User lacks required permissions	403
upstream_error	Error from model inference backend	502, 503
invalid_request	Malformed request body or parameters	400

AI-Specific Routing Information

These fields provide information about how the request was routed through the AI router.

Field	Type	Description	Example
model_name	string	Name of the AI model requested	llama2-7b, gpt-3.5-turbo
model_route	string	Name of the ModelRoute resource used	default/llama2-route-v1
model_server	string	ModelServer that handled the request	default/llama2-server
selected_pod	string	Specific pod that processed the inference	llama2-deployment-5f7b8c9d-xk2p4
request_id	string	Unique identifier for request tracing	550e8400-e29b-41d4-a716-446655440000

Token Information

Token usage metrics for the inference request.

Field	Type	Description	Example
input_tokens	integer	Number of tokens in the request prompt	150
output_tokens	integer	Number of tokens generated in response	75

Timing Breakdown

All timing values are in milliseconds and provide detailed performance metrics.

Field	Type	Description	Example
duration_total	integer	Total end-to-end request processing time (ms)	2350
duration_request_processing	integer	Router request processing overhead (ms)	45
duration_upstream_processing	integer	Model inference time on backend pod (ms)	2180
duration_response_processing	integer	Response processing and serialization time (ms)	5

Timing Phases

1. Request Processing: Time spent parsing the request, authentication, rate limiting, and routing decisions
2. Upstream Processing: Time spent on actual model inference in the backend pod
3. Response Processing: Time spent formatting and serializing the response

Example Access Logs

Successful Request (JSON Format)

{
  "timestamp": "2024-01-15T10:30:45.123Z",
  "method": "POST",
  "path": "/v1/chat/completions",
  "protocol": "HTTP/1.1",
  "status_code": 200,
  "model_name": "llama2-7b",
  "model_route": "default/llama2-route-v1",
  "model_server": "default/llama2-server",
  "selected_pod": "llama2-deployment-5f7b8c9d-xk2p4",
  "request_id": "550e8400-e29b-41d4-a716-446655440000",
  "input_tokens": 150,
  "output_tokens": 75,
  "duration_total": 2350,
  "duration_request_processing": 45,
  "duration_upstream_processing": 2180,
  "duration_response_processing": 5
}

Failed Request with Error (JSON Format)

{
  "timestamp": "2024-01-15T10:35:22.456Z",
  "method": "POST",
  "path": "/v1/chat/completions",
  "protocol": "HTTP/1.1",
  "status_code": 504,
  "error": {
    "type": "timeout",
    "message": "Model inference timeout after 30s"
  },
  "model_name": "llama2-7b",
  "model_route": "default/llama2-route-v1",
  "model_server": "default/llama2-server",
  "selected_pod": "llama2-deployment-5f7b8c9d-xk2p4",
  "request_id": "660e8400-e29b-41d4-a716-446655440001",
  "input_tokens": 200,
  "output_tokens": 0,
  "duration_total": 30050,
  "duration_request_processing": 50,
  "duration_upstream_processing": 30000,
  "duration_response_processing": 0
}

Text Format Example

[2024-01-15T10:30:45.123Z] "POST /v1/chat/completions HTTP/1.1" 200 model_name=llama2-7b model_route=default/llama2-route-v1 model_server=default/llama2-server selected_pod=llama2-deployment-5f7b8c9d-xk2p4 request_id=550e8400-e29b-41d4-a716-446655440000 tokens=150/75 timings=2350ms(45+2180+5)

Text Format with Error

[2024-01-15T10:35:22.456Z] "POST /v1/chat/completions HTTP/1.1" 504 error=timeout:Model inference timeout after 30s model_name=llama2-7b model_route=default/llama2-route-v1 model_server=default/llama2-server selected_pod=llama2-deployment-5f7b8c9d-xk2p4 request_id=660e8400-e29b-41d4-a716-446655440001 tokens=200/0 timings=30050ms(50+30000+0)

Configuration

Access logging is configured through environment variables in the kthena router deployment:

Environment Variables

Variable	Description	Default	Valid Values
ACCESS_LOG_ENABLED	Enable or disable access logging	true	true, false
ACCESS_LOG_FORMAT	Log output format	text	json, text
ACCESS_LOG_OUTPUT	Where to write logs	stdout	stdout, stderr, or file path