Fix fabric8io#1264: Failure referencing a previous staged image in FR…

…OM clause

doc/changelog.md

@@ -7,6 +7,7 @@
   - Treat bridged and default network mode the same #1234
   - Fix NPE when cacheFrom is missing from config #1274
   - Fix healthy option regression introduced in 0.25.0 #1279
+  - Failure referencing a previous staged image in FROM clause #1264
 
 * **0.31.0** (2019-08-10)
   - Fix test cases on Windows ([#1220](https://github.com/fabric8io/docker-maven-plugin/issues/1220))

src/main/java/io/fabric8/maven/docker/util/DockerFileUtil.java

@@ -17,6 +17,7 @@
 
 import java.io.*;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -53,9 +54,17 @@ private DockerFileUtil() {}
     public static List<String> extractBaseImages(File dockerFile, FixedStringSearchInterpolator interpolator) throws IOException {
         List<String[]> fromLines = extractLines(dockerFile, "FROM", interpolator);
         LinkedList<String> result = new LinkedList<>();
+        Map<String, String> fromAlias = new HashMap<>();
         for (String[] fromLine :  fromLines) {
             if (fromLine.length > 1) {
-                result.add(fromLine[1]);
+                if (fromLine.length == 2) { // FROM image:tag use case
+                    result.add(fromLine[1]);
+                } else if (fromLine.length == 4) { // FROM image:tag AS alias use case
+                    if (!fromAlias.containsKey(fromLine[1])) {
+                        result.add(fromLine[1]);
+                    }
+                    fromAlias.put(fromLine[3], fromLine[1]);
+                }
             }
         }
         return result;

src/test/java/io/fabric8/maven/docker/util/DockerFileUtilTest.java

@@ -59,6 +59,16 @@ public void testMultiStage() throws Exception {
         assertEquals(false, fromClauses.hasNext());
     }
 
+    @Test
+    public void testMultiStageNamed() throws Exception {
+        File toTest = copyToTempDir("Dockerfile_multi_stage_named_build_stages");
+        Iterator<String> fromClauses = DockerFileUtil.extractBaseImages(
+                toTest, FixedStringSearchInterpolator.create()).iterator();
+
+        assertEquals("fabric8/s2i-java", fromClauses.next());
+        assertEquals(false, fromClauses.hasNext());
+    }
+
     private File copyToTempDir(String resource) throws IOException {
         File dir = Files.createTempDirectory("d-m-p").toFile();
         File ret = new File(dir, "Dockerfile");

src/test/resources/io/fabric8/maven/docker/util/Dockerfile_multi_stage_named_build_stages

@@ -0,0 +1,12 @@
+# Dockerfile with multi-stage builds with named stages
+FROM fabric8/s2i-java as BUILD
+
+RUN ls -la /
+
+FROM BUILD as DEVELOPMENT
+
+RUN ls -la /
+
+FROM BUILD AS DEPOYLABLE
+
+RUN ls -la /