log-management

name	log-management
description	Centralized logging and analysis
license	MIT
compatibility	opencode
metadata	{"audience":"developer, devops-engineer, sre","category":"devops"}

What I do

• Design centralized logging architectures
• Implement log collection and aggregation
• Configure log parsing and enrichment
• Build log-based alerting and dashboards
• Ensure compliance with logging standards
• Analyze logs for troubleshooting and insights

When to use me

• When investigating production issues
• When implementing observability
• When meeting compliance requirements
• When building audit trails
• When analyzing user behavior
• When debugging distributed systems

Key Concepts

Log Aggregation Architecture

┌─────────────────────────────────────────────────────┐
│              Application Logs                      │
│  (stdout, file, syslog)                             │
└──────────────────────┬──────────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────────┐
│              Log Collector                          │
│  (Fluentd, Filebeat, Vector)                        │
└──────────────────────┬──────────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────────┐
│              Log Storage                            │
│  (Elasticsearch, Loki, S3)                          │
└──────────────────────┬──────────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────────┐
│              Visualization                         │
│  (Kibana, Grafana, CloudWatch)                      │
└─────────────────────────────────────────────────────┘

Fluentd Configuration

<source>
  @type tail
  @id input_tail
  path /var/log/nginx/access.log
  pos_file /var/log/fluentd/nginx-access.log.pos
  tag nginx.access
  <parse>
    @type nginx
  </parse>
</source>

<filter nginx.access>
  @type parser
  key_name log
  <parse>
    @type json
  </parse>
</filter>

<match nginx.**>
  @type elasticsearch
  host elasticsearch
  port 9200
  logstash_format true
  logstash_prefix nginx
  flush_interval 10s
</match>

Loki LogQL

# Find error logs
{job="myapp"} |= "ERROR"

# Exclude health checks
{job="myapp"} != "/health"

# Parse JSON logs
{job="myapp"} | json | level="error"

# Rate calculation
sum(rate({job="myapp"}[5m]))

# Latency percentiles
histogram_quantile(0.99, sum(rate({job="myapp"}[5m])) by (le, path))

Structured Logging

import logging
import json
from datetime import datetime

class JSONFormatter(logging.Formatter):
    def format(self, record):
        log_data = {
            "timestamp": datetime.utcnow().isoformat(),
            "level": record.levelname,
            "message": record.getMessage(),
            "module": record.module,
            "function": record.funcName,
            "line": record.lineno
        }
        
        if record.exc_info:
            log_data["exception"] = self.formatException(record.exc_info)
            
        if hasattr(record, "user_id"):
            log_data["user_id"] = record.user_id
            
        if hasattr(record, "request_id"):
            log_data["request_id"] = record.request_id
            
        return json.dumps(log_data)

# Usage
logger = logging.getLogger(__name__)
logger.info("User logged in", extra={"user_id": 123, "request_id": "abc"})

ELK Stack

# docker-compose.yml
version: '3'
services:
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:8.10.0
    environment:
      - discovery.type=single-node
      - xpack.security.enabled=false
    ports:
      - "9200:9200"
      
  kibana:
    image: docker.elastic.co/kibana/kibana:8.10.0
    ports:
      - "5601:5601"
    depends_on:
      - elasticsearch
      
  logstash:
    image: docker.elastic.co/logstash/logstash:8.10.0
    ports:
      - "5044:5044"
    volumes:
      - ./logstash.conf:/usr/share/logstash/pipeline/logstash.conf

Log Retention Policies

Data Type	Retention	Storage
Application Logs	30 days	Hot
Audit Logs	1 year	Warm
Security Logs	2 years	Cold
Compliance Logs	7 years	Archive

Key Metrics

• Log ingestion rate (GB/day)
• Search latency (p95, p99)
• Index storage size
• Query performance
• Alert response time
• Cost per GB