Log Format
The default log output from Spring Boot resembles the following example:
2023-04-27T19:52:05.903Z INFO 2954 --- [ main] o.s.b.d.f.s.MyApplication : Starting MyApplication using Java 17.0.6 with PID 2954 (/opt/apps/myapp.jar started by myuser in /opt/apps/) 2023-04-27T19:52:05.922Z INFO 2954 --- [ main] o.s.b.d.f.s.MyApplication : No active profile set, falling back to 1 default profile: "default" 2023-04-27T19:52:08.014Z INFO 2954 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2023-04-27T19:52:08.040Z INFO 2954 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2023-04-27T19:52:08.042Z INFO 2954 --- [ main] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.5] 2023-04-27T19:52:08.306Z INFO 2954 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2023-04-27T19:52:08.313Z INFO 2954 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2264 ms 2023-04-27T19:52:09.228Z INFO 2954 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path '' 2023-04-27T19:52:09.247Z INFO 2954 --- [ main] o.s.b.d.f.s.MyApplication : Started MyApplication in 4.573 seconds (process running for 5.541)
The following items are output:
-
Date and Time: Millisecond precision and easily sortable.
-
Log Level:
ERROR
,WARN
,INFO
,DEBUG
, orTRACE
. -
Process ID.
-
A
---
separator to distinguish the start of actual log messages. -
Thread name: Enclosed in square brackets (may be truncated for console output).
-
Logger name: This is usually the source class name (often abbreviated).
-
The log message.
Logback does not have a FATAL level.
It is mapped to ERROR .
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