Missing Structured Failure Report in Spring Boot WAR Deployments

Direct answer

Spring Boot will emit a FailureAnalyzer report only when the failure occurs after the SpringApplication instance has been created and the context refresh is attempted. In a WAR deployed to an external servlet container (Tomcat, Jetty, etc.) this happens if the exception is thrown during the SpringBootServletInitializer‑driven startup. If the exception occurs earlier – e.g., during ServletContainerInitializer processing, class‑loading issues, or before Spring’s logging system is initialized – the container logs the raw exception and the FailureAnalyzer chain is not invoked, so no structured report appears.

Confirmed facts

• FailureAnalyzer is part of Spring Boot’s diagnostics framework and is run by SpringApplication when SpringApplication.run(...) throws an exception.
• In WAR mode, SpringBootServletInitializer creates the SpringApplication and calls run; any exception thrown from that point triggers the FailureAnalyzer chain.
• The servlet container’s own error handling (e.g., Tomcat’s org.apache.catalina.core.StandardContext logging) can intercept and log exceptions before Spring gets a chance to run its analyzers.
• If Spring’s logging is not yet initialized (very early failures), FailureAnalyzer output may go to System.err and be missed in the container’s log files.

Steps to verify and enable the report for your case

1. Deploy the WAR and reproduce the startup failure.
2. Check the container’s console/log for a line containing "FailureAnalyzer" or "Failed to analyze" (Spring Boot logs this at ERROR level).
3. If you do not see such a line, enable debug logging for the diagnostics package: add logging.level.org.springframework.boot.diagnostics=DEBUG to application.properties (or via -Dlogging.level.org.springframework.boot.diagnostics=DEBUG on the JVM).
4. If the failure still yields no analyzer output, the exception is likely occurring before SpringBootServletInitializer’s onStartup completes. Examine the container’s early‑startup logs for class‑not‑found, missing servlet‑container‑initializer, or bean‑definition‑loading errors.
5. To capture deployment‑specific failures, create a custom FailureAnalyzer (annotate with @Component or declare in META-INF/spring.factories) and ensure it is on the classpath of the WAR. Its analyze method will be called only for failures that reach the SpringApplication refresh step.
6. Confirm invocation by adding a distinctive log statement (e.g., log.error("[CustomAnalyzer] triggered for {}", failure.getMessage());) inside your analyzer and verifying it appears in the logs when the failure occurs.

Missing diagnostic detail that would change the recommendation

Knowing whether the exception is thrown before or after SpringBootServletInitializer’s onStartup method would determine if a custom FailureAnalyzer can help. If you can share the exact stack trace or the phase (e.g., "ServletContainerInitializer", "context refresh", "bean creation"), I can advise whether adding a FailureAnalyzer is appropriate or if the issue must be resolved at the container or class‑path level.