Java Collector
Analyze Java projects to collect build tool info, dependencies, CI/CD command tracking, test scope, JUnit test results, and JaCoCo coverage. Supports Maven and Gradle.
java to your lunar-config.yml:uses: github://earthly/lunar-lib/collectors/java@v1.0.5
What This Integration Collects
This integration includes 9 collectors that gather metadata from your systems.
project
Detects Java project structure including build tools (Maven/Gradle), Java version from build config, wrapper scripts, and static analysis tool configuration. Writes project metadata to .lang.java.
dependencies
Extracts direct dependencies from pom.xml (using Python XML parsing with property resolution) or gradle.lockfile. Writes dependency data to .lang.java.dependencies.
cicd
Records java/javac commands executed in CI pipelines along with the Java version. Writes command strings and version info to .lang.java.cicd.cmds.
maven-cicd
Records Maven commands executed in CI pipelines along with the Maven version. Detects version from installation path, wrapper properties, or mvn --version. Writes to .lang.java.maven.cicd.cmds.
gradle-cicd
Records Gradle commands executed in CI pipelines along with the Gradle version. Writes to .lang.java.gradle.cicd.cmds.
sbt-cicd
Records sbt commands executed in CI pipelines along with the sbt version.
Detects version from sbt --version or project/build.properties.
Writes to .lang.java.sbt.cicd.cmds. Sister of the scala collector's cicd
sub-collector — both fire on the same sbt invocation, each writing into
its own language namespace for mixed Scala/Java sbt repos.
test-scope
Determines whether Maven/Gradle test commands run all modules or a subset. Writes scope to .lang.java.tests.scope as "all" or "module" and signals test execution via .testing.source.
test-coverage
Extracts JaCoCo coverage percentage from XML reports after test runs. Parses coverage from standard Maven/Gradle report locations and writes results to both .lang.java.tests.coverage and .testing.coverage.
test-results
When a Maven or Gradle build finishes, reads the JUnit XML reports it wrote (Surefire, Failsafe, Gradle test tasks) and records how many tests passed, failed and were skipped. Writes the totals to .lang.java.tests.results and .testing.results, whether every test passed to .testing.all_passing, and one entry per build to .testing.runs.
How Collectors Fit into Lunar
Lunar watches your code and CI/CD systems to collect SDLC data from config files, test results, IaC, deployment configurations, security scans, and more.
Collectors are the automatic data-gathering layer. They extract structured metadata from your repositories and pipelines, feeding it into Lunar's centralized database where guardrails evaluate it to enforce your engineering standards.
Learn How Lunar Works →Example Collected Data
This collector writes structured metadata to the Component JSON. Here's an example of the data it produces:
{
"lang": {
"java": {
"version": "17",
"build_systems": ["maven"],
"pom_xml_exists": true,
"build_gradle_exists": false,
"mvnw_exists": true,
"gradlew_exists": false,
"gradle_lockfile_exists": false,
"checkstyle_configured": true,
"spotbugs_configured": false,
"source": { "tool": "java", "integration": "code" },
"cicd": {
"cmds": [
{ "cmd": "java -jar app.jar", "version": "17.0.2" }
]
},
"maven": {
"cicd": {
"cmds": [
{ "cmd": "mvn clean install", "version": "3.9.6" }
]
}
},
"sbt": {
"cicd": {
"cmds": [
{ "cmd": "sbt test", "version": "1.9.7" }
]
}
},
"tests": {
"scope": "all",
"results": {
"total": 156,
"passed": 152,
"failed": 1,
"skipped": 3,
"source": { "tool": "maven", "integration": "ci" }
},
"coverage": {
"percentage": 72.5,
"source": { "tool": "jacoco", "integration": "ci" }
}
},
"dependencies": {
"direct": [
{ "path": "org.springframework:spring-core", "version": "6.1.3", "indirect": false }
],
"transitive": [],
"source": { "tool": "maven", "integration": "code" }
}
}
},
"testing": {
"source": { "tool": "maven-surefire", "integration": "ci" },
"results": { "total": 156, "passed": 152, "failed": 1, "skipped": 3 },
"all_passing": false,
"runs": [
{
"pipeline": "CI",
"run_id": "36909154652",
"attempt": 1,
"job": "build",
"step": 4,
"total": 156,
"passed": 152,
"failed": 1,
"skipped": 3,
"all_passing": false
}
],
"coverage": {
"percentage": 72.5,
"source": { "tool": "jacoco", "integration": "ci" }
}
}
}Documentation
View on GitHubJava Collector
Collects Java project information, CI/CD commands, dependencies, test results, and test coverage.
Overview
This collector gathers metadata about Java projects including build tool detection (Maven/Gradle), dependency graphs, CI/CD command tracking, test scope, JUnit test results, and JaCoCo coverage metrics. It supports Maven, Gradle, and sbt build systems (the sbt sub-collector covers Java-only sbt repos and sits alongside the scala collector for mixed Scala/Java). Code hooks analyze project structure statically, while CI hooks observe build and test commands at runtime.
Note: The CI-hook collectors (test-results, test-coverage, test-scope, cicd, maven-cicd, gradle-cicd, sbt-cicd) don't run builds or tests—they observe and collect data from commands that your CI pipeline already runs.
Collected Data
This collector writes to the following Component JSON paths:
| Path | Type | Description |
|---|---|---|
.lang.java |
object | Java project metadata (version, build systems, file existence) |
.lang.java.dependencies |
object | Direct dependencies from pom.xml or gradle.lockfile |
.lang.java.cicd |
object | Java runtime CI/CD command tracking with version |
.lang.java.maven.cicd |
object | Maven CI/CD command tracking with version |
.lang.java.gradle.cicd |
object | Gradle CI/CD command tracking with version |
.lang.java.sbt.cicd |
object | sbt CI/CD command tracking with version |
.lang.java.tests |
object | Test scope, JUnit test results, and JaCoCo coverage information |
.testing.results |
object | Normalized test totals: total, passed, failed, skipped (dual-write from JUnit XML) |
.testing.all_passing |
boolean | false if any test failed or errored |
.testing.runs |
array | One entry per build (CI run, attempt, job, step, totals, all_passing) |
.testing.coverage |
object | Normalized cross-language coverage (dual-write from JaCoCo) |
.testing.source |
object | Normalized testing indicator |
Collectors
This plugin provides the following collectors (use include to select a subset):
| Collector | Hook Type | Description |
|---|---|---|
project |
code | Detects Java project structure, build tools, Java version, wrappers |
dependencies |
code | Extracts dependencies from pom.xml or gradle.lockfile |
cicd |
ci-before-command | Tracks java/javac commands in CI with version |
maven-cicd |
ci-before-command | Tracks Maven commands in CI with version |
gradle-cicd |
ci-before-command | Tracks Gradle commands in CI with version |
sbt-cicd |
ci-before-command | Tracks sbt commands in CI with version |
test-scope |
ci-before-command | Determines test scope (all vs module) |
test-coverage |
ci-after-command | Extracts JaCoCo coverage from XML reports |
test-results |
ci-after-command | Totals passed/failed/skipped tests from Surefire, Failsafe, and Gradle JUnit XML reports |
Test results
test-results runs when a Maven or Gradle build finishes. mvn, mvnw, gradle and gradlew all exec into the build's JVM, so the hook is on that java process, whose exit is the end of the build. It reads the TEST-*.xml files in target/surefire-reports/ and target/failsafe-reports/ (Maven) or build/test-results/<task>/ (Gradle) under the build's directory, and writes nothing when there are none. If the reports can't be parsed it exits with an error rather than recording partial totals.
- It counts each
<testcase>: a failure or error fails it,<skipped>skips it, and a test that passed on a Surefire rerun counts as passed. - Gradle's test-retry plugin lists every attempt as its own test, so a test that passed on retry still counts its failed attempt. Set
reports.junitXml.mergeReruns = trueto report it the way Surefire does. .testing.resultsand.testing.all_passinghold the last build to finish at a commit..testing.runskeeps every build, andtesting.passingfails if the latest attempt of any of them failed, so a passing job can't hide a failing one.- Reports left over from an earlier build are counted too. CI checkouts start clean by default; a reused workspace needs
mvn clean/gradle clean.
Installation
Add to your lunar-config.yml:
collectors:
- uses: github://earthly/lunar-lib/collectors/java@v1.0.0
on: ["domain:your-domain"] # replace with your own domain or tags
include:
- project # Build tools and Java version
- dependencies # Maven and Gradle dependencies
- cicd # java and javac commands in CI
- maven-cicd # Maven commands in CI
- gradle-cicd # Gradle commands in CI
- sbt-cicd # sbt commands in CI
- test-scope # Test scope in CI
- test-coverage # JaCoCo coverage
- test-results # JUnit XML test results
Open Source
This collector is open source and available on GitHub. Contribute improvements, report issues, or fork it for your own use.
Common Use Cases
Explore guardrails that use data from Java Collector.
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