task : include userId in the log messages by using MDC.

src/main/java/ru/mystamps/web/support/spring/security/SecurityConfig.java

@@ -203,4 +203,13 @@ public FilterRegistrationBean getResetLocaleFilter(
 		return bean;
 	}
 
+	@Bean
+	public FilterRegistrationBean userMdcLoggingFilter() {
+		FilterRegistrationBean bean = new FilterRegistrationBean(
+			new UserMdcLoggingFilter()
+		);
+		bean.addUrlPatterns("/*");
+		return bean;
+	}
+
 }

src/main/java/ru/mystamps/web/support/spring/security/UserMdcLoggingFilter.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2009-2019 Slava Semushin <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+package ru.mystamps.web.support.spring.security;
+
+import org.slf4j.MDC;
+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;
+
+public class UserMdcLoggingFilter extends OncePerRequestFilter {
+	private static final String USER_ID = "userId";
+
+	@Override
+	protected void doFilterInternal(
+		HttpServletRequest request,
+		HttpServletResponse response,
+		FilterChain filterChain)
+		throws ServletException, IOException {
+
+		Integer userId = SecurityContextUtils.getUserId();
+		if (userId != null) {
+			MDC.put(USER_ID, userId.toString());
+		}
+
+		try {
+			filterChain.doFilter(request, response);
+		} finally {
+			MDC.remove(USER_ID);
+		}
+	}
+
+}

src/main/resources/application.properties

@@ -36,6 +36,11 @@ server.compression.min-response-size: 512
 
 security.filter-dispatcher-types: REQUEST, ERROR
 
+# See for details:
+# https://docs.spring.io/spring-boot/docs/1.5.x/reference/html/boot-features-logging.html#boot-features-custom-log-configuration
+# https://logback.qos.ch/manual/layouts.html
+logging.pattern.level: [user:%-2X{userId}] %5p
+
 app.mail.admin.email: [email protected]
 app.mail.admin.lang: ru
 app.mail.robot.email: [email protected]