Build report, console modes, and warning control

[gnodet]

Build Report Foundation

What users see

--console=plain — compact CI output (default when CI=true)

One line per completed module, no ANSI, no status bar. Auto-selected on CI (CI=true, JENKINS_URL, etc.):

$ mvn validate --console=plain
[INFO] Apache Maven [1/38] ................................ SUCCESS [  0.539 s]
[INFO] Maven 4 API [2/38] ................................. SUCCESS [  0.017 s]
[INFO] Maven 4 API :: Meta annotations [3/38] ............. SUCCESS [  0.019 s]
[INFO] Maven 4 API :: Dependency Injection [4/38] ......... SUCCESS [  0.018 s]
[INFO] Maven 4 API :: XML [5/38] .......................... SUCCESS [  0.027 s]
[INFO] Maven 4 API :: Model [6/38] ........................ SUCCESS [  0.070 s]
...
[INFO] Maven 4 CLI [35/38] ................................ SUCCESS [  0.240 s]
[INFO] Maven Plugin Testing Mechanism [36/38] ............. SUCCESS [  0.162 s]
[INFO] Maven Embedder (deprecated) [37/38] ................ SUCCESS [  0.178 s]
[INFO] Apache Maven Distribution [38/38] .................. SUCCESS [  0.514 s]
[INFO]
[INFO] BUILD SUCCESS
[INFO] 38 modules | 38 passed
[INFO] Total time:  5.519 s
[INFO] Full report: target/build-reports/build-report-latest.json

--console=rich — live status bar (default on interactive TTY)

During the build, the bottom of the terminal shows a live JLine status area that updates in place. All plugin INFO/WARN output is suppressed — only ERRORs scroll above the status bar:

 Maven 4.1.0-SNAPSHOT ─ building Apache Maven 4.1.0-SNAPSHOT
 ● maven-core  maven-compiler-plugin:compile  8s
 ● maven-api-core  maven-surefire-plugin:test  3s
────────────────────────────────────────────────────────────────────
 ✓ ✓ ✓ ● ● ○ ○ ○ ○ ○ [5/10]  32s  ↓ core-4.1.0.jar 256KB/512KB

With large reactors (where per-module indicators don't fit), the separator becomes a proportional progress bar:

 Maven 4.1.0-SNAPSHOT ─ building Apache Camel 4.22.0-SNAPSHOT
 ● camel-jaxb  flatten-maven-plugin:flatten  0s
 ● camel-core  maven-compiler-plugin:compile  8s
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━────────────────────────────────────── [77/673]  1m 18s

At the end, the status bar is torn down and replaced with a compact summary:

BUILD SUCCESS
38 modules | 38 passed
Total time:  5.772 s
Full report: target/build-reports/build-report-latest.json

When diagnostics are present:

BUILD SUCCESS
38 modules | 38 passed
Diagnostics: 3 warnings — run mvnlog to see details
Total time:  32.1s
Full report: target/build-reports/build-report-latest.json

--console=machine — JSON lines for tools and LLM agents

One JSON object per line, designed for piping to jq, IDE integrations, and AI agents:

$ mvn validate --console=machine
{"event":"build.started","timestamp":"...","projectCount":38,"goals":"validate","profiles":"signing-key"}
{"event":"module.started","timestamp":"...","module":"Apache Maven","groupId":"org.apache.maven","artifactId":"maven","version":"4.1.0-SNAPSHOT","index":1,"total":38}
{"event":"mojo.started","timestamp":"...","module":"Apache Maven","plugin":"maven-enforcer-plugin","goal":"enforce","phase":"validate","executionId":"enforce-bytecode-version"}
{"event":"log","timestamp":"...","level":"INFO","module":"maven","logger":"...","message":"Rule 0: org.apache.maven.enforcer.rules.version.RequireJavaVersion passed"}
{"event":"mojo.succeeded","timestamp":"...","module":"Apache Maven","plugin":"maven-enforcer-plugin","goal":"enforce","duration":0.33}
{"event":"module.succeeded","timestamp":"...","module":"Apache Maven","duration":0.543}
...
{"event":"build.finished","timestamp":"...","status":"SUCCESS","duration":4.363,"total":38,"passed":38,"failed":0,"skipped":0}

--console=verbose — full output (Maven 4.0 default)

Unchanged from today's Maven 4.0 behavior — all per-mojo banners, plugin output, download progress:

$ mvn validate --console=verbose
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] Apache Maven                                                       [pom]
[INFO] Maven 4 API                                                        [pom]
[INFO] Maven 4 API :: Meta annotations                                    [jar]
...
[INFO] -----------------------< org.apache.maven:maven >-----------------------
[INFO] Building Apache Maven 4.1.0-SNAPSHOT                              [1/38]
[INFO]   from pom.xml
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] --- enforcer:3.6.3:enforce (enforce-bytecode-version) @ maven ---
[INFO] Rule 0: org.apache.maven.enforcer.rules.version.RequireJavaVersion passed
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.447 s
[INFO] Finished at: 2026-08-06T07:58:06+02:00
[INFO] ------------------------------------------------------------------------

--console=auto (the default)

Selects automatically: CI=true or JENKINS_URL set → plain; interactive TTY → rich; otherwise → verbose.

Warning summary at end of build

All console modes show a deduplicated warning summary at end of build (unless --warning-mode=none):

[WARNING] ┌──────────────────────────────────────────────────────────────────────┐
[WARNING] │ Build validation completed with 3 warning(s):                       │
[WARNING] ├──────────────────────────────────────────────────────────────────────┤
[WARNING] │ [WARNING] 'version' contains an expression but should be a          │
[WARNING] │  constant. maven-api-core:4.1.0-SNAPSHOT  ×3                        │
[WARNING] │ [WARNING] 'build.plugins.plugin.version' for                        │
[WARNING] │  org.apache.maven.plugins:maven-surefire-plugin is missing. ×1      │
[WARNING] └──────────────────────────────────────────────────────────────────────┘

--warning-mode controls behavior:

Mode	During build	End of build	Exit code
all (default)	show warnings	show summary	0
summary	suppress inline	show summary	0
none	suppress all	suppress all	0
fail	show warnings	show summary	1 (if any warning)

Version info on failure

When the build fails, Maven and Java version are printed to help with bug reports:

BUILD FAILURE
38 modules | 31 passed | 1 failed | 6 skipped
Total time:  32.1s
Maven:       4.1.0-SNAPSHOT
Java:        21.0.11 (Eclipse Adoptium)
Full report: target/build-reports/build-report-latest.json

Structured build report JSON

Every build writes target/build-reports/build-report-latest.json:

{
  "formatVersion": 1,
  "status": "SUCCESS",
  "duration": "PT5.535S",
  "startTime": "2026-08-06T05:58:15.816Z",
  "mavenVersion": "4.1.0-SNAPSHOT",
  "javaVersion": "21.0.11",
  "goals": ["validate"],
  "project": "org.apache.maven:maven:4.1.0-SNAPSHOT",
  "multiModule": true,
  "threads": 1,
  "modules": [
    {
      "groupId": "org.apache.maven",
      "artifactId": "maven",
      "version": "4.1.0-SNAPSHOT",
      "status": "SUCCESS",
      "duration": "PT0.577S",
      "mojos": [
        {
          "plugin": "maven-enforcer-plugin",
          "goal": "enforce",
          "phase": "validate",
          "status": "SUCCESS",
          "duration": "PT0.346S",
          "output": [...]
        }
      ]
    }
  ]
}

mvnlog — build report viewer

After a build completes, mvnlog reads the report JSON and renders a human-readable view:

$ mvnlog                    # view latest build report
$ mvnlog warnings           # just the deduplicated warnings
$ mvnlog module core        # output from a specific module
$ mvnlog --json             # raw JSON output for tools

---

How it works

Console mode architecture

Each console mode is a pair of cooperating classes:

Mode	BuildEventListener	ExecutionListener
rich	RichBuildEventListener (JLine status bar)	RichExecutionEventLogger (suppress per-mojo banners)
plain	PlainBuildEventListener (no-op status)	PlainExecutionEventLogger (one line per module)
machine	MachineBuildEventListener (JSON log/transfer events)	MachineExecutionEventLogger (JSON lifecycle events)
verbose	existing SimpleBuildEventListener	existing ExecutionEventLogger

The BuildEventListener handles real-time events (log messages, transfer progress), while the ExecutionListener handles lifecycle events (session/project/mojo start/finish).

Build report pipeline

1. BuildReportCollector — injected ExecutionListener that captures every lifecycle event, mojo execution, and log message into an in-memory report
2. BuildReportWriter — writes the report to target/build-reports/build-report-latest.json at session end
3. BuilderProblem — universal diagnostic currency: model validation warnings, plugin validation, and (with PR Fix #12643: Pipe structured BuilderProblems into DiagnosticCollector #12647) plugin-reported diagnostics all flow through BuilderProblem into DiagnosticCollector

Warning deduplication

Warnings are deduplicated by key (e.g. pom:version-expression) and counted. The end-of-build summary shows each unique warning with its count, regardless of how many modules triggered it.

DiagnosticReporter (PR #12647)

A new Maven 4 API service that plugins can inject to report structured diagnostics:

• BuilderProblem objects with severity, key, source location, suggestion, and documentation URL
• Per-location dedup keys (e.g. compiler:unchecked:src/Foo.java:42) prevent duplicate warnings from incremental builds
• Implemented in maven-compiler-plugin (PR Report structured BuilderProblems from compiler diagnostics maven-compiler-plugin#1101)

---

Follow-up PRs

• Fix #12643: Pipe structured BuilderProblems into DiagnosticCollector #12647 — DiagnosticReporter API: injectable service for Maven 4 plugins to report structured BuilderProblem objects
• Report structured BuilderProblems from compiler diagnostics maven-compiler-plugin#1101 — Compiler plugin integration: reports compile warnings as BuilderProblem with per-location dedup keys