Docker Compose Logs: A Comprehensive Guide

Essential Docker Compose Log Commands

1. Basic Log Viewing

# View logs of all services defined in docker-compose.yml
docker-compose logs

# View logs of specific services
docker-compose logs service1 service2

# Follow logs in real-time (similar to tail -f)
docker-compose logs -f

# Show timestamps with logs
docker-compose logs -t

# Combination of following and timestamps
docker-compose logs -f -t service1

2. Filtering and Limiting Logs

# View only the last N lines of logs
docker-compose logs --tail=100

# Filter logs since a specific time
docker-compose logs --since="2023-01-01T00:00:00"

# Until a specific time
docker-compose logs --until="2023-01-02T00:00:00"

# Combine with specific services
docker-compose logs --tail=50 service1

3. Log Management Commands

# Check if logs exist and where they are stored
docker-compose ps

# Remove stopped service containers (and their logs)
docker-compose rm

# Remove volumes (be careful as this can delete persistent data)
docker-compose down -v

# Force recreation of containers and their logs
docker-compose up -d --force-recreate

4. Advanced Inspection

# Inspect container details including log configuration
docker inspect container_name

# View logs directly from Docker (alternative method)
docker logs container_name

# View log drivers and logging configuration
docker info | grep Logging

Understanding Docker Compose Logging Architecture

Docker Compose relies on Docker's logging system, which uses logging drivers to handle container logs. By default, Docker uses the json-file driver that stores logs as JSON files on the host.

Here's a diagram showing how logging works in Docker Compose:

# Example docker-compose.yml with custom logging options

version: '3.8'

services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"
        
  api:
    image: node:alpine
    command: node server.js
    logging:
      driver: "local"
      options:
        max-size: "20m"
        max-file: "5"
        
  database:
    image: postgres:13
    logging:
      driver: "syslog"
      options:
        syslog-address: "tcp://localhost:514"
        tag: "{{.Name}}"
        
  metrics:
    image: prometheus:latest
    logging:
      driver: "fluentd"
      options:
        fluentd-address: "localhost:24224"
        tag: "docker.{{.Name}}"