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🐳 Docker Compose Logs Guide

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📋 Overview

This guide explains how to view and configure logs when running the Mail Archiver application using Docker Compose. Proper log management is essential for monitoring application health, troubleshooting issues, and understanding system behavior.

📖 Viewing Docker Compose Logs

Basic Log Commands

To view logs from all services in your Docker Compose setup:

docker compose logs

To view logs for a specific service (e.g., the Mail Archiver application):

docker compose logs mailarchive-app

Real-time Log Streaming

To follow logs in real-time (similar to tail -f):

docker compose logs -f

To follow logs for a specific service:

docker compose logs -f mailarchive-app

Log Filtering and Options

Show last N lines of logs: 

docker compose logs --tail=100

Show logs since a specific time: 

docker compose logs --since=1h

Show logs until a specific time: 

docker compose logs --until=2025-01-01T12:00:00

Show timestamps in logs: 

docker compose logs -t

📝 Log Level Configuration

The Mail Archiver application supports various log levels that control the verbosity of the output. You can configure these levels using environment variables in your docker-compose.yml file.

Available Log Levels

The following log levels are available, ordered from most verbose to least verbose:

  • Trace - Most detailed logging, including internal framework messages
  • Debug - Detailed debugging information for development and troubleshooting
  • Information - General information about application flow (default level)
  • Warning - Warning messages about potential issues
  • Error - Error messages about failed operations
  • Critical - Critical error messages that require immediate attention
  • None - No logging output

Default Log Configuration

By default, the application uses the following log level configuration: - Default: Information - Microsoft.AspNetCore: Warning (reduces framework noise) - Microsoft.EntityFrameworkCore.Database.Command: Warning (reduces database command noise)

Configuring Log Levels in Docker Compose

To customize log levels, add the following environment variables to your docker-compose.yml file under the mailarchive-app service:

services:
  mailarchive-app:
    image: s1t5/mailarchiver:latest
    environment:
      # Other environment variables...

      # Logging Settings (Optional)
      - Logging__LogLevel__Default=Information
      - Logging__LogLevel__Microsoft_AspNetCore=Warning
      - Logging__LogLevel__Microsoft_EntityFrameworkCore_Database_Command=Warning

Example: Debug Configuration

For troubleshooting purposes, you might want to enable more verbose logging:

services:
  mailarchive-app:
    image: s1t5/mailarchiver:latest
    environment:
      # Other environment variables...

      # Verbose Logging for Debugging
      - Logging__LogLevel__Default=Debug
      - Logging__LogLevel__Microsoft_AspNetCore=Information
      - Logging__LogLevel__Microsoft_EntityFrameworkCore_Database_Command=Debug

Example: Production Configuration

For production environments, you might want to reduce log verbosity to improve performance and reduce log volume:

services:
  mailarchive-app:
    image: s1t5/mailarchiver:latest
    environment:
      # Other environment variables...

      # Production Logging (Reduced Verbosity)
      - Logging__LogLevel__Default=Warning
      - Logging__LogLevel__Microsoft_AspNetCore=Error
      - Logging__LogLevel__Microsoft_EntityFrameworkCore_Database_Command=Error

🔍 Understanding Log Output

Log Format

Logs follow this general format: 

timestamp [log-level] category - message

Example: 

2025-01-15T10:30:45.123Z [Information] MailArchiver.Services.EmailService - Starting email synchronization for account user@example.com

Common Log Categories

  • MailArchiver.Services.* - Application service logs
  • MailArchiver.Controllers.* - Web API controller logs
  • Microsoft.AspNetCore - ASP.NET Core framework logs
  • Microsoft.EntityFrameworkCore - Entity Framework logs
  • Microsoft.Extensions.Hosting - Hosting-related logs

🛠️ Troubleshooting Tips

1. Finding Error Messages

To quickly find error messages in the logs: 

docker compose logs mailarchive-app | grep -i error

2. Monitoring Specific Operations

To monitor email synchronization: 

docker compose logs -f mailarchive-app | grep -i sync

3. Checking for Warnings

To check for warning messages: 

docker compose logs mailarchive-app | grep -i warning

📊 Log Management Best Practices

For Development

  • Use Debug or Information level for detailed troubleshooting
  • Enable real-time log streaming during development
  • Monitor logs continuously while testing new features

For Production

  • Use Warning or Error level to reduce log volume
  • Implement log rotation to prevent disk space issues
  • Consider centralized logging solutions for multi-container setups
  • Regularly review logs for security events and performance issues