Add build scan url as GitHub workflow step output (#37)

README.md

@@ -24,30 +24,34 @@ jobs:
         run: ./mvnw clean package
 [...]
 ```
-_Note:_<br>
-When authenticated access is required to publish a Build Scan®, it is recommended to provide as input `develocity-access-key` to the `maven-setup` step. This triggers a request for a [short-lived access token](https://docs.gradle.com/develocity/api-manual/#short_lived_access_tokens) instead of relying on the `DEVELOCITY_ACCESS_KEY` environment variable.
+
+> [!NOTE]  
+> When authenticated access is required to publish a Build Scan®, it is recommended to provide as input `develocity-access-key` to the `maven-setup` step. This triggers a request for a [short-lived access token](https://docs.gradle.com/develocity/api-manual/#short_lived_access_tokens) instead of relying on the `DEVELOCITY_ACCESS_KEY` environment variable.
 
 ### Implementation details
 
 The action enables two features:
 - Display a summary of the Maven builds as a GitHub workflow summary or as a pull-request comment
 - Capture unpublished Build Scan® data as a workflow artifact per job with prefix `build-scan-data-maven`, which can then be published in a dependent workflow.
 
-#### Summary
-
-By default, a summary will be added to the GitHub workflow calling the action (can be skipped with `add-job-summary` is set to `false`):
+#### Workflow Summary
+By default, a summary will be added to the GitHub workflow calling the action (can be skipped if `add-job-summary` is set to `false`):
 
 ![workflow](./doc/summary-workflow.png)
 
+#### Pull-request Comment
+
 By default, a comment will be added to the pull-request with the summary (can be skipped if `add-pr-comment` is set to `false`):
 
 ![comment](./doc/summary-comment.png)
 
-_Note:_<br>
-- The job name is computed by appending `github.job` to the current matrix value (if present) but can be overridden with `job-name` input.
-- The pull-request comment is overwriting the previous summary comment if present, this means that if several jobs have a setup-maven step, 
+> [!NOTE]
+> - The job name is computed by appending `github.job` to the current matrix value (if present) but can be overridden with `job-name` input.
+> - The pull-request comment is overwriting the previous summary comment if present, this means that if several jobs have a setup-maven step, 
   only the last will have its summary commented in the PR. It is recommended to disable the pull-request summary in this case (`add-pr-comment: false`).  
 
+#### Raw Summary data
+
 Additionally, the summary details will be accessible in `$RUNNER_TEMP/build-scan-data-maven/build-metadata.json` with the format below:
 
 ```json
@@ -94,12 +98,15 @@ The _capture_ can be _enabled_/_disabled_ separately:
 The process is handled by a [Maven extension](https://maven.apache.org/guides/mini/guide-using-extensions.html) `maven-build-scan-capture-extension.jar` which is running during each Maven invocation.
 The extension is automatically registered by configuring the environment `MAVEN_OPTS=-Dmaven.ext.classpath=<PATH_TO_EXTENSION>`.
 
-_Note:_<br>
-If `MAVEN_OPTS` environment variable is set in the step invoking the `mvn` command, the extension won't be registered.
+> [!NOTE]
+> If `MAVEN_OPTS` environment variable is set in the step invoking the `mvn` command, the extension won't be registered.
 Make sure to use `MAVEN_OPTS: ${{ env.MAVEN_OPTS }} <EXTRA_PARAMETERS>` construction to append the extra parameters and have the extension registered.
 
 The captured files are added as workflow artifact (one artifact per job).
 
+When a Build Scan link is captured, it is added as output to the step invoking Maven.
+The output name is `build-scan-url` and can be used in subsequent steps of the workflow.
+
 **Event Triggers**:
 
 - `pull_request`: To capture unpublished Build Scan®
@@ -130,8 +137,8 @@ The following permissions are required for this action to operate:
 When submitting a pull request from a forked GitHub repository, a GitHub workflow that validates the change cannot publish a Build Scan® 
 as workflows from forked repositories do not have access to secrets. An access token is required to publish a Build Scan®.
 
-_Note:_<br>
-The `Approve and Run` manual step documented [here](https://docs.github.com/en/actions/managing-workflow-runs/approving-workflow-runs-from-public-forks) must be enabled on the GitHub repository configuration to meet legal requirements (this is the default configuration).
+> [!NOTE]
+> The `Approve and Run` manual step documented [here](https://docs.github.com/en/actions/managing-workflow-runs/approving-workflow-runs-from-public-forks) must be enabled on the GitHub repository configuration to meet legal requirements (this is the default configuration).
 
 ### Maven workflow
 
@@ -180,11 +187,11 @@ jobs:
           develocity-access-key: ${{ secrets.<DEVELOCITY_ACCESS_KEY> }}
 ```
 
-_Note:_<br>
-Some parameters need to be adjusted here:
-- The workflow name (here `PR Build`) triggered when a pull-request is submitted
-- The Develocity URL (here `https://<MY_DEVELOCITY_URL>`)
-- The secret name holding the Develocity access key (here `<DEVELOCITY_ACCESS_KEY>`)
+> [!NOTE]
+> Some parameters need to be adjusted here:
+> - The workflow name (here `PR Build`) triggered when a pull-request is submitted
+> - The Develocity URL (here `https://<MY_DEVELOCITY_URL>`)
+> - The secret name holding the Develocity access key (here `<DEVELOCITY_ACCESS_KEY>`)
 
 #### Implementation details
 

maven-build-scan-capture-extension/src/main/java/com/gradle/MavenBuildScanCaptureListener.java

@@ -12,8 +12,11 @@
 import java.io.File;
 import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
 import java.util.Optional;
 import java.util.UUID;
 import java.util.stream.Stream;
@@ -84,12 +87,25 @@ private String getMavenVersion() {
     void captureBuildScanLink(PublishedBuildScan publishedBuildScan) {
         if(configuration.isCaptureBuildScanLinks(buildState.isBuildFailure())) {
             LOGGER.info("Capturing build scan link");
-            buildState.setBuildScanLink(publishedBuildScan.getBuildScanUri().toString());
+            String buildScanLink = publishedBuildScan.getBuildScanUri().toString();
+            buildState.setBuildScanLink(buildScanLink);
+            addToGitHubOutput("build-scan-url", buildScanLink);
         } else {
             LOGGER.debug("Build scan link capture disabled");
         }
     }
 
+    private void addToGitHubOutput(String key, String value) {
+        try {
+            String githubOutput = System.getenv("GITHUB_OUTPUT");
+            if (githubOutput != null) {
+                Files.writeString(Paths.get(githubOutput), key + "=" + value + "\n", StandardCharsets.UTF_8, StandardOpenOption.APPEND);
+            }
+        } catch (IOException e) {
+            LOGGER.info("Unable to add " + key + " to GitHub output " + e.getMessage());
+        }
+    }
+
     void captureBuildScanMetadata() {
         if(configuration.isBuildScanRepublication()) {
             appendBuildScanLinkToMetadataFile();