This is a short code examples for realizing log tracing && log marking in Spring-Boot Applications

FeignLogFiltering.java

import feign.RequestInterceptor;
import feign.RequestTemplate;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.stereotype.Component;

/**
 * @project some-api
 * @created 2021-07-09 15:37
 * <p>
 * @author Alexander A. Kropotin
 */
@Slf4j
@Component("FeignLogFiltering")
public class FeignLogFiltering implements RequestInterceptor {

    @Override
    public void apply(RequestTemplate requestTemplate) {
        String requestId = MDC.get("traceId");

        if(requestId != null) {
            requestTemplate.header("traceId", requestId);
        }
    }
}

logback-spring.xml

<configuration >
    <include resource="/org/springframework/boot/logging/logback/base.xml" />

    <variable name="log-file-path" value="./log" />
    <variable name="application-name" value="vtd-dc-api" />
    <variable name="log-server-address" value="172.17.0.1" />

    <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <Pattern>
                %green(%d{yyyy-MM-dd HH:mm:ss}) %highlight(%-5level) %yellow([traceId=%X{traceId}, spanId=%X{spanId}]) %green(%logger{36}) : %msg%n%throwable
            </Pattern>
        </layout>
    </appender>

    <appender name="RollingFile" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${log-file-path}/${application-name}.log</file>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <Pattern>%d %level %logger{36} [%mdc] : %msg%n%throwable</Pattern>
        </encoder>

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${log-file-path}/archived/${application-name}-%d{yyyy-MM-dd}.%i.log
            </fileNamePattern>
            <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                <maxFileSize>2048MB</maxFileSize>
            </timeBasedFileNamingAndTriggeringPolicy>
        </rollingPolicy>
    </appender>

    <root level="INFO">
        <appender-ref ref="Console" />
        <appender-ref ref="RollingFile" />
    </root>

</configuration>

LogFiltering.java

import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.UUID;

/**
 * @project some-api
 * @created 2021-07-09 15:37
 * <p>
 * @author Alexander A. Kropotin
 */
@Slf4j
@Component("LogFiltering")
public class LogFiltering extends OncePerRequestFilter {

    private static final String REQUEST_ID = "traceId";

    @Override
    protected void doFilterInternal(HttpServletRequest request,
                                    HttpServletResponse response,
                                    FilterChain filterChain) throws ServletException, IOException {
        String requestId = request.getHeader(REQUEST_ID);
        if (requestId == null) {
            requestId = UUID.randomUUID().toString();
        }

        MDC.put(REQUEST_ID, requestId);

        try {
            log.trace("Started process request with {} : {}", REQUEST_ID, requestId);
            filterChain.doFilter(request, response);
        } finally {
            MDC.clear();
        }
    }
}

logback example for Loki Appender

<configuration >
    <include resource="/org/springframework/boot/logging/logback/base.xml" />

    <variable name="log-file-path" value="./log" />
    <variable name="application-name" value="vtd-dc-api" />
    <variable name="log-server-address" value="172.17.0.1" />

    <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <Pattern>
                %green(%d{yyyy-MM-dd HH:mm:ss}) %highlight(%-5level) %yellow([traceId=%X{traceId}, spanId=%X{spanId}]) %green(%logger{36}) : %msg%n%throwable
            </Pattern>
        </layout>
    </appender>

    <appender name="RollingFile" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${log-file-path}/${application-name}.log</file>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <Pattern>%d %level %logger{36} [%mdc] : %msg%n%throwable</Pattern>
        </encoder>

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${log-file-path}/archived/${application-name}-%d{yyyy-MM-dd}.%i.log
            </fileNamePattern>
            <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                <maxFileSize>2048MB</maxFileSize>
            </timeBasedFileNamingAndTriggeringPolicy>
        </rollingPolicy>
    </appender>

    <appender name="LOKI" class="com.github.loki4j.logback.Loki4jAppender">
        <http class="com.github.loki4j.logback.ApacheHttpSender">
            <url>http://${log-server-address}:3100/loki/api/v1/push</url>
        </http>
        <format>
            <label>
                <pattern>service=${application-name}, host=${HOSTNAME}, level=%level, thread=%thread</pattern>
            </label>
            <message>
                <pattern>dt=%d lvl=%level traceId=%X{traceId} class=%logger{36} : msg=%msg%n%throwable</pattern>
            </message>
            <sortByTime>true</sortByTime>
        </format>
    </appender>

    <root level="INFO">
        <appender-ref ref="Console" />
        <appender-ref ref="RollingFile" />
        <appender-ref ref="LOKI" />
    </root >

</configuration>