Logback Configuration (RFC-27) Skill

Logback Configuration (RFC-27)

RFC-27 compliant static Logback configuration for Java services.

When to use this skill

Setting up logging configuration for new Java services
Reviewing or updating logback.xml configuration
Configuring environment-specific logging
Setting up log file rotation and retention
Configuring appenders for different outputs (console, file, JSON)

Skill Contents

Available Resources

📚 references/ - Detailed documentation

configuration patterns

Quick Start

1. Create logback-spring.xml

Place in src/main/resources/logback-spring.xml:

<?xml version="1.0" encoding="UTF-8"?>
<configuration scan="true" scanPeriod="30 seconds">
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>

    <!-- Console appender for local development -->
    <springProfile name="local">
        <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
            <encoder>
                <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
            </encoder>
        </appender>
        <root level="INFO">
            <appender-ref ref="CONSOLE"/>
        </root>
    </springProfile>

    <!-- JSON appender for production -->
    <springProfile name="!local">
        <appender name="JSON" class="ch.qos.logback.core.ConsoleAppender">
            <encoder class="net.logstash.logback.encoder.LogstashEncoder"/>
        </appender>
        <root level="INFO">
            <appender-ref ref="JSON"/>
        </root>
    </springProfile>
</configuration>

2. Do NOT Commit logback.xml to Git

Per RFC-27, logback.xml should NOT be in version control. Use logback-spring.xml instead, which supports Spring profiles.

Configuration Structure

Required Elements

| Element | Purpose | |---------|---------| | <configuration> | Root element with optional scan attributes | | <appender> | Defines output destination | | <encoder> | Formats log messages | | <root> | Default logging level |

Spring Profile Integration

Use <springProfile> to apply configuration conditionally:

<springProfile name="production">
    <!-- Production-specific config -->
</springProfile>

<springProfile name="!production">
    <!-- Non-production config -->
</springProfile>

Appender Types

| Appender | Use Case | |----------|----------| | ConsoleAppender | Standard output (container logs) | | RollingFileAppender | File with rotation | | AsyncAppender | Non-blocking wrapper |

Console Appender (Production)

<appender name="JSON" class="ch.qos.logback.core.ConsoleAppender">
    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
        <includeMdcKeyName>traceId</includeMdcKeyName>
        <includeMdcKeyName>spanId</includeMdcKeyName>
    </encoder>
</appender>

Environment Configuration

Log Levels per Environment

| Environment | Root Level | Notes | |-------------|------------|-------| | local | DEBUG | Verbose for development | | development | INFO | Standard logging | | staging | INFO | Match production | | production | INFO | Minimize noise |

Logger Overrides

<!-- Reduce noise from specific libraries -->
<logger name="org.apache.kafka" level="WARN"/>
<logger name="org.springframework.web" level="INFO"/>
<logger name="com.bitso" level="DEBUG"/>

References

| Reference | Description | |-----------|-------------| | references/configuration-patterns.md | Detailed configuration examples |

Related Rules

java-structured-logs - Structured logging standards (RFC-34)

Related Skills

| Skill | Purpose | |-------|---------| | structured-logs-rfc-34 | Structured logging format | | dynamic-loglevel-rfc-27 | Runtime log level control |

Agent Skills: Logback Configuration (RFC-27)

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