Fix stop-app in the interactive CLI without Actuator or JMX

[jamesfredley]

Fixes #13695

Problem

stop-app in the interactive Grails shell does not work. The base profile stop-app command tries two mechanisms, both of which fail on a modern setup:

1. JMX via com.sun.tools.attach.VirtualMachine, loading management-agent.jar - that jar was removed in Java 9+, and the code uses javax.*. This silently fails on JDK 17/21.
2. HTTP fallback that POSTs to the Spring Boot Actuator /actuator/shutdown endpoint - disabled by default, so it throws FileNotFoundException (HTTP 404), reporting "Application not running" even though it is.

Enabling the Actuator shutdown endpoint is not an acceptable fix: it is intrusive and affects production for the sake of a development-time stop-app.

Approach (CLI only, no Actuator, no JMX)

In the interactive shell, run-app starts the application as an asynchronous Gradle bootRun build. That build already has a Gradle Tooling API CancellationTokenSource - it is what CTRL-C uses to stop the app. The problem is that the token was only reachable through the run-app command's ExecutionContext, so stop-app (a separate ExecutionContext in the same CLI JVM) had no handle to it.

This PR introduces a small shared registry so stop-app can cancel the running build directly, without POOL.shutdownNow() (which would kill the executor and block re-running) and without exiting the CLI.

Changes

• New RunningApplicationRegistry (grails-shell-cli) - tracks the CancellationTokenSource of running run-app builds. stopAll() only requests cancellation; the build deregisters its own token when it finishes. awaitStop(timeout) waits for the build to tear down.
• GradleUtil - wireCancellationSupport now returns the token source, created via the public GradleConnector.newCancellationTokenSource() instead of the internal DefaultCancellationTokenSource. A new runBuildWithConsoleOutput(context, trackForStop, closure) overload registers/deregisters the token around the build.
• GradleInvoker - tracks only the bootRun task (matches bootRun or :bootRun), so transient builds (compile, test, console) are not affected.
• stop-app.groovy - rewritten to cancel via the registry and wait for shutdown; obsolete port/host flags removed.
• run-app.groovy - no longer passes -Dgrails.management.endpoints.shutdown.enabled=true (only existed to enable the Actuator endpoint); the JVM shutdown hook now calls RunningApplicationRegistry.stopAll() directly instead of re-invoking the stop-app command.
• Docs - updated stop-app reference and the getting-started running/debugging guide.

Tests

• RunningApplicationRegistrySpec covers register/deregister, stopAll requesting cancellation without removing tokens, resilience when a token throws, and awaitStop success/timeout.
• ./gradlew :grails-shell-cli:test --tests "org.grails.cli.gradle.RunningApplicationRegistrySpec" passes.

Manual verification still recommended

The forked application JVM is torn down by Gradle when the bootRun build is cancelled (the same path CTRL-C uses). A manual run of grails run-app -> grails stop-app -> grails run-app on JDK 21 (Windows and Linux) is recommended before merge to confirm no orphaned process and that the port is freed.

Notes

• This is a draft for review of the approach on 7.0.x. The linked issue is milestoned for 8.0.0-M3; opening here first per discussion.

[Copilot]

Pull request overview

Fixes a long-broken stop-app in the interactive Grails CLI by replacing the JMX-attach and Spring Boot Actuator /actuator/shutdown HTTP fallback (both of which fail on modern JDKs/default configurations) with a CLI-only registry that lets stop-app cancel the running bootRun Gradle Tooling API build directly via its CancellationTokenSource.

Changes:

• New RunningApplicationRegistry tracks running bootRun cancellation tokens; stop-app.groovy is rewritten to cancel via the registry and awaitStop, dropping the JMX/HTTP shutdown code and the port/host flags.
• GradleUtil.wireCancellationSupport now uses the public GradleConnector.newCancellationTokenSource() and returns the token; a new runBuildWithConsoleOutput(context, trackForStop, closure) overload registers/deregisters tokens around the build.
• GradleInvoker opts only the bootRun/:bootRun task into tracking; run-app.groovy drops -Dgrails.management.endpoints.shutdown.enabled=true and the shutdown hook calls RunningApplicationRegistry.stopAll(); reference and getting-started docs updated to match the new flow.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
grails-shell-cli/src/main/groovy/org/grails/cli/gradle/RunningApplicationRegistry.groovy	New registry of running app cancellation token sources with stop/await operations.
grails-shell-cli/src/test/groovy/org/grails/cli/gradle/RunningApplicationRegistrySpec.groovy	Spock spec covering register/deregister, stopAll, throw resilience, and awaitStop success/timeout.
grails-shell-cli/src/main/groovy/org/grails/cli/gradle/GradleUtil.groovy	Switches to public newCancellationTokenSource(), returns the token, and adds a trackForStop overload that registers/deregisters around the build.
grails-shell-cli/src/main/groovy/org/grails/cli/gradle/GradleInvoker.groovy	Enables stop tracking only for bootRun/:bootRun invocations.
grails-profiles/base/commands/stop-app.groovy	Rewritten to cancel via the registry and await shutdown; removes JMX and Actuator HTTP fallback and port/host flags.
grails-profiles/base/commands/run-app.groovy	Drops Actuator shutdown system property; shutdown hook now calls RunningApplicationRegistry.stopAll() directly.
grails-doc/src/en/ref/Command Line/stop-app.adoc	Documents the new CLI-only, same-session shutdown semantics and removes obsolete arguments.
grails-doc/src/en/guide/gettingStarted/runningAndDebuggingAnApplication.adoc	Updates the example output to match the new status messages.

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