Fix fabric8io#544: Avoiding chown to reduce the image size

doc/changelog.md

@@ -6,6 +6,9 @@
   - Allow merging of image configurations using <imagesMap> ([#360](https://github.com/fabric8io/docker-maven-plugin/issues/360))
   - Update to joda-time 2.10.4 (#706)
   - Add docker:build support for 'network' option #1030
+  - Avoiding chown to reduce the image size (#544)
+    (_Note: Assembly user format `user:user:user` with the third user option has been marked deprecated
+    and will not be available in future versions of plugin_)
   - Failure referencing a previous staged image in FROM clause #1264
   - Treat bridged and default network mode the same (#1234)
   - Fix NPE when cacheFrom is missing from config (#1274)

src/main/asciidoc/inc/build/_assembly.adoc

@@ -61,6 +61,7 @@ assembly configuration
 It has the general format `user[:group[:run-user]]`. The user and group can be given either as numeric user- and group-id or as names. The group id is optional.
 
 If a third part is given, then the build changes to user `root` before changing the ownerships, changes the ownerships and then change to user `run-user` which is then used for the final command to execute. This feature might be needed, if the base image already changed the user (e.g. to 'jboss') so that a `chown` from root to this user would fail.
+(_**This third user part has been marked as deprecated and will not be supported in future versions of this plugin.**_)
 
 For example, the image `jboss/wildfly` use a "jboss" user under which all commands are executed. Adding files in Docker always happens under the UID root. These files can only be changed to "jboss" is the `chown` command is executed as root. For the following commands to be run again as "jboss" (like the final `standalone.sh`), the plugin switches back to user `jboss` (this is this "run-user") after changing the file ownership. For this example a specification of
 `jboss:jboss:jboss` would be required.

src/main/java/io/fabric8/maven/docker/assembly/DockerFileBuilder.java

@@ -195,28 +195,26 @@ private static void buildOption(StringBuilder b, DockerFileOption option, Object
 
     private void addCopy(StringBuilder b) {
         if (assemblyUser != null) {
-            String tmpDir = createTempDir();
-            addCopyEntries(b, tmpDir);
-
-            String[] userParts = StringUtils.split(assemblyUser, ":");
-            String userArg = userParts.length > 1 ? userParts[0] + ":" + userParts[1] : userParts[0];
-            String chmod = "chown -R " + userArg + " " + tmpDir + " && cp -rp " + tmpDir + "/* / && rm -rf " + tmpDir;
-            if (userParts.length > 2) {
-                DockerFileKeyword.USER.addTo(b, "root");
-                DockerFileKeyword.RUN.addTo(b, chmod);
-                DockerFileKeyword.USER.addTo(b, userParts[2]);
-            } else {
-                DockerFileKeyword.RUN.addTo(b, chmod);
+            String[] userParts = assemblyUser.split(":");
+
+            for (CopyEntry entry : copyEntries) {
+                String dest = (basedir.equals("/") ? "" : basedir) + "/" + entry.destination;
+                if (userParts.length > 2) {
+                    DockerFileKeyword.USER.addTo(b, "root");
+                }
+                DockerFileKeyword.ADD.addTo(b, " --chown="
+                        + (userParts.length > 1 ?
+                          userParts[0] + ":" + userParts[1] :
+                          userParts[0]), entry.source, dest);
+                if (userParts.length > 2) {
+                    DockerFileKeyword.USER.addTo(b, userParts[2]);
+                }
             }
         } else {
             addCopyEntries(b, "");
         }
     }
 
-    private String createTempDir() {
-         return "/tmp/" + UUID.randomUUID().toString();
-    }
-
     private void addCopyEntries(StringBuilder b, String topLevelDir) {
         for (CopyEntry entry : copyEntries) {
             String dest = topLevelDir + (basedir.equals("/") ? "" : basedir) + "/" + entry.destination;

src/main/java/io/fabric8/maven/docker/assembly/DockerFileKeyword.java

@@ -9,6 +9,7 @@
 public enum DockerFileKeyword
 {
     MAINTAINER,
+    ADD,
     EXPOSE,
     FROM,
     SHELL,

src/test/java/io/fabric8/maven/docker/assembly/DockerFileBuilderTest.java

@@ -228,10 +228,7 @@ public void illegalNonAbsoluteBaseDir() {
     public void testAssemblyUserWithChown() {
         String dockerFile = new DockerFileBuilder().assemblyUser("jboss:jboss:jboss")
                                                    .add("a","a/nested").add("b","b/deeper/nested").content();
-        String EXPECTED_REGEXP = "chown\\s+-R\\s+jboss:jboss\\s+([^\\s]+)"
-                                 + "\\s+&&\\s+cp\\s+-rp\\s+\\1/\\*\\s+/\\s+&&\\s+rm\\s+-rf\\s+\\1";
-        Pattern pattern = Pattern.compile(EXPECTED_REGEXP);
-        assertTrue(pattern.matcher(dockerFile).find());
+        assertThat(dockerfileToMap(dockerFile), hasEntry("ADD", "--chown=jboss:jboss b /maven/b/deeper/nested"));
     }
 
     @Test