fix(logging): use one logback-spring.xml and silence logback status from main()

[adityamparikh]

Problem

After #189 the logging setup had three coupled pieces and a test whose only job was to keep them coupled:

Piece	Job
logback.xml	a NopStatusListener and nothing else, so logback's own pre-Spring init stays off stdout in the native image
logback-spring.xml	the real configuration, with the <springProfile> appenders
logging.config=classpath:logback-spring.xml in application.properties	steer Boot past logback.xml, which initializeWithConventions() would otherwise stop at, never loading the -spring variant

That is not how Boot expects to be configured. The reference documentation asks for one file, resolved by convention, and reserves logging.config for pointing at an external file. Two classpath files disambiguated by a property is a workaround, and LoggingConfigurationTest existed to stop anyone from "cleaning it up" — which #104 had in fact done in a stray commit that would now break native STDIO.

Change

The only thing logback.xml did was install a status listener before Boot exists. Logback has a first-class knob for exactly that, the logback.statusListenerClass system property, and I verified the ordering in logback 1.5.32 (Boot 3.5.14's BOM): ContextInitializer.autoConfig() runs checkVersions() (the source of the native-only |-WARN), then StatusListenerConfigHelper.installIfAsked() (reads the property), and LogbackServiceProvider calls StatusPrinter.printInCaseOfErrorsOrWarnings() only when StatusUtil.contextHasStatusListener() is false. So the listener does not need to exist before the WARN, only before the print, and the property is read in between.

main()                          sets logback.statusListenerClass (unless already set)
  └─ SpringApplication.<clinit> first LoggerFactory touch
       └─ ContextInitializer     checkVersions() → |-WARN (native only)
                                 installIfAsked() → NopStatusListener   ← property read here
                                 BasicConfigurator (no logback.xml)
       └─ LogbackServiceProvider contextHasStatusListener() == true → nothing printed
  └─ LoggingApplicationListener  logback-spring.xml by convention → <springProfile> appenders

• Main.main() sets the property as its first statement. An operator's explicit -Dlogback.statusListenerClass=...OnConsoleStatusListener wins, so logback itself can still be debugged.
• logback.xml deleted.
• logging.config removed from application.properties. LOGGING_CONFIG in the environment still works as Boot's normal override for an external file.
• SolrNativeHints no longer registers logback.xml; the logback-spring.xml hint stays as belt-and-braces for the non-AOT path.
• LoggingConfigurationTest now pins the convention instead of the coupling: no standard-location logback file on the classpath, no logging.config in application.properties, and Main installs a listener that StatusListenerConfigHelper honours. Written first and watched fail on main before the change.
• AGENTS.md, dev-docs/graalvm-native-image.md, docs/security/stdio.md and the keycloak.md troubleshooting section (which still described the pre-fix(logging): load logback-spring.xml without breaking native stdout #189 "no HTTP logs" state) updated.

logging.pattern.console= in application-stdio.properties is untouched: it is the idiom Spring AI documents for STDIO servers and does not depend on any of the above.

Verification

Check	Result
LoggingConfigurationTest on main before the change	2 of 5 fail (logback.xml present, logging.config set), compile error for the missing Main API
./gradlew build (JDK 25)	403 tests, 0 failures, 7 skipped; McpClientStdioIntegrationTest (JVM java -jar over MCP STDIO) 40/40
./gradlew dockerIntegrationTest -Pnative (native STDIO image driven over MCP STDIO)	BUILD SUCCESSFUL in 8m 46s; freshly built solr-mcp:1.0.0-SNAPSHOT-native-stdio (GraalVM CE 25.0.2, Paketo): DockerImageMcpClientStdioIntegrationTest 40/40, DockerImageStdioIntegrationTest 4/4

Related

• Supersedes the logback.xml removal commit (777168e8) carried by fix(config): reject a solr.url SolrJ cannot connect to at bind time #104; that PR should drop the commit on its next rebase, since with this change there is nothing left to remove.
• fix(logging): load logback-spring.xml without breaking native stdout #189 introduced the coupling this replaces; the native-only failure it fixed is covered by the same Docker test.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Wh7SJkZhL1uuK7pYc3SLk8

[adityamparikh]

Native verification done: ./gradlew dockerIntegrationTest -Pnative — BUILD SUCCESSFUL in 8m 46s on a freshly built solr-mcp:1.0.0-SNAPSHOT-native-stdio (GraalVM CE 25.0.2). DockerImageMcpClientStdioIntegrationTest 40/40 and DockerImageStdioIntegrationTest 4/4, so the native STDIO stream stays clean with logback.xml gone and the status listener set from main(). PR description updated with the same numbers.

[epugh]

Fixing main!