GH-1288: As a smith I want to fix the Eclipse nightly build (missing yarn) (#1289)

GH-1288: As a smith I want to fix the Eclipse nightly build (missing yarn) (#1289)

Author: Quang Minh Tran

docker-build/Dockerfile

@@ -98,7 +98,7 @@ RUN ARCH= && dpkgArch="$(dpkg --print-architecture)" && \
 #
 # Yarn install
 #
-ENV YARN_VERSION 1.13.0
+ENV YARN_VERSION 1.15.2
 
 RUN set -ex && \
     for key in \

eclipse-nightly.jenkinsfile

@@ -24,6 +24,7 @@ pipeline {
 
     environment {
         NODEJS_PATH= '/shared/common/node-v10.15.3-linux-x64/bin'
+        YARN_PATH = '/shared/common/yarn/1.15.2/bin'
         PATH       = "${PATH}"                                          +
                      ":/shared/common/apache-ant-1.9.6/bin"             +
                      ":/shared/common/maven/apache-maven-3.5.2/bin/"    +

plugins/org.eclipse.n4js/src/org/eclipse/n4js/binaries/BinariesConstants.java

@@ -52,6 +52,11 @@ public final class BinariesConstants {
 	 */
 	public static final String DEFAULT_NODE_PATH_VM_ARG = "org.eclipse.n4js.defaultNodePath";
 
+	/**
+	 * Default yarn path, similar to {@code DEFAULT_NODE_PATH_VM_ARG}
+	 */
+	public static final String DEFAULT_YARN_PATH_VM_ARG = "org.eclipse.n4js.defaultYarnPath";
+
 	/**
 	 * Jenkins environment variable for the {@code Node.js} binary path. Points to the actual binary (with an absolute
 	 * path) instead of pointing to the folder containing the binary.
@@ -62,6 +67,16 @@ public final class BinariesConstants {
 	 */
 	public static final String NODEJS_PATH_ENV = "NODEJS_PATH";
 
+	/**
+	 * Jenkins environment variable for the {@code yarn} binary path. Points to the actual binary (with an absolute
+	 * path) instead of pointing to the folder containing the binary.
+	 *
+	 * <p>
+	 * Even if it is available the {@link #DEFAULT_YARN_PATH_VM_ARG <code>org.eclipse.n4js.defaultYarnPath</code>} VM
+	 * argument might override this configuration.
+	 */
+	public static final String YARN_PATH_ENV = "YARN_PATH";
+
 	/**
 	 * The (fallback) built-in default {@code Node.js} path if the above VM or ENV property is not specified.
 	 *
@@ -74,6 +89,18 @@ public final class BinariesConstants {
 			? new File("C:" + separator + "Program Files" + separator + "nodejs").getAbsolutePath()
 			: new File(separator + "usr" + File.separator + "local" + separator + "bin").getAbsolutePath();
 
+	/**
+	 * The (fallback) built-in default {@code yarn} path if the above VM or ENV property is not specified.
+	 *
+	 * <ul>
+	 * <li>On Windows systems: {@code C:\Program Files\yarn}</li>
+	 * <li>On Unix systems: {@code /usr/local/bin}</li>
+	 * </ul>
+	 */
+	public static final String BUILT_IN_DEFAULT_YARN_PATH = isWindows()
+			? new File("C:" + separator + "Program Files" + separator + "yarn").getAbsolutePath()
+			: new File(separator + "usr" + File.separator + "local" + separator + "bin").getAbsolutePath();
+
 	/** The minimum {@code Node.js} version. */
 	public static final VersionNumber NODE_MIN_VERSION = SemverUtils.createVersionNumber(10, 13, 0);
 	/** The label for {@code Node.js}. */

plugins/org.eclipse.n4js/src/org/eclipse/n4js/binaries/BinariesLocatorHelper.java

@@ -113,10 +113,30 @@ public Path findNodePath() {
 	 * @return string with absolute path to the binary
 	 */
 	public Path findYarnPath() {
+		Path yarnPathCandidate = null;
 
-		Path yarnPathCandidate;
+		// 1. lookup by DEFAULT_YARN_PATH_VM_ARG
+		yarnPathCandidate = resolveFolderContaingBinary(
+				tryGetEnvOrSystemVariable(BinariesConstants.DEFAULT_YARN_PATH_VM_ARG));
+		if (yarnPathCandidate != null) {
+			info("User specified default Yarn path will be used: '" + yarnPathCandidate
+					+ ".' based on the '" + BinariesConstants.DEFAULT_YARN_PATH_VM_ARG + "' VM argument.");
+			return yarnPathCandidate;
+		}
+		debug("Could not resolve node path from '" + BinariesConstants.DEFAULT_NODE_PATH_VM_ARG
+				+ "' VM argument.");
 
-		// 1. lookup by PATH
+		// 2. lookup by YARN_PATH_ENV
+		yarnPathCandidate = resolveFolderContaingBinary(
+				tryGetEnvOrSystemVariable(BinariesConstants.YARN_PATH_ENV));
+		if (yarnPathCandidate != null) {
+			info("User specified default yarn path will be used: '" + yarnPathCandidate
+					+ ".' based on the '" + BinariesConstants.YARN_PATH_ENV + "' environment argument.");
+			return yarnPathCandidate;
+		}
+		debug("Could not resolve yarn path from '" + BinariesConstants.YARN_PATH_ENV);
+
+		// 3. lookup by PATH
 		yarnPathCandidate = resolveFolderContaingBinary(
 				ExecutableLookupUtil.findInPath(BinariesConstants.YARN_BINARY_NAME));
 		if (yarnPathCandidate != null) {
@@ -126,7 +146,7 @@ public Path findYarnPath() {
 		}
 		debug("Could not resolve yarn path from OS PATH variable.");
 
-		// 2. lookup by OS query
+		// 4. lookup by OS query
 		yarnPathCandidate = resolveFolderContaingBinary(
 				lookForBinary(BinariesConstants.YARN_BINARY_NAME));
 		if (yarnPathCandidate != null) {
@@ -137,8 +157,11 @@ public Path findYarnPath() {
 		}
 		debug("Could not resolve yarn path from OS dynamic lookup.");
 
-		debug("Falling back to node path ...");
-		return findNodePath();
+		// 5. use default, whether it is correct or not.
+		info("Could not resolve yarn path. Falling back to default path: " + yarnPathCandidate);
+		yarnPathCandidate = new File(BinariesConstants.BUILT_IN_DEFAULT_YARN_PATH).toPath();
+
+		return yarnPathCandidate;
 	}
 
 	private String lookForBinary(String binaryName) {