Add support for --squash experimental build option

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## upcoming release
+- Add support for --squash experimental build option ([248][])
+
+[248]: https://github.com/spotify/dockerfile-maven/pull/248
+
 ## 1.4.9 (released October 25 2018)
 - Upgrade docker-client dep from 8.14.2 to 8.14.3 to fix spotify/docker-client#1100
 

docs/usage.md

@@ -39,3 +39,4 @@ mvn clean package -Ddockerfile.skip
 | `dockerfile.build.noCache` | Do not use cache when building the image. | no | false |
 | `dockerfile.build.cacheFrom` | Docker image used as cache-from. Pulled in advance if not exist locally or `pullNewerImage` is `false` | no | none |
 | `dockerfile.buildArgs` | Custom build arguments. | no | none |
+| `dockerfile.build.squash` | Squash newly built layers into a single new layer (experimental API 1.25+). | no | false |

plugin/src/main/java/com/spotify/plugin/dockerfile/BuildMojo.java

@@ -97,6 +97,9 @@ public class BuildMojo extends AbstractDockerMojo {
   @Parameter(property = "dockerfile.build.cacheFrom")
   private List<String> cacheFrom;
 
+  @Parameter(property = "dockerfile.build.squash", defaultValue = "false")
+  private boolean squash;
+
   @Override
   public void execute(DockerClient dockerClient)
       throws MojoExecutionException, MojoFailureException {
@@ -109,7 +112,7 @@ public void execute(DockerClient dockerClient)
 
     final String imageId = buildImage(
         dockerClient, log, verbose, contextDirectory, repository, tag, pullNewerImage, noCache,
-        buildArgs, cacheFrom);
+        buildArgs, cacheFrom, squash);
 
     if (imageId == null) {
       log.warn("Docker build was successful, but no image was built");
@@ -142,7 +145,8 @@ static String buildImage(@Nonnull DockerClient dockerClient,
                            boolean pullNewerImage,
                            boolean noCache,
                            @Nullable Map<String,String> buildArgs,
-                           @Nullable List<String> cacheFrom)
+                           @Nullable List<String> cacheFrom,
+                           boolean squash)
       throws MojoExecutionException, MojoFailureException {
 
     log.info(MessageFormat.format("Building Docker context {0}", contextDirectory));
@@ -189,6 +193,10 @@ static String buildImage(@Nonnull DockerClient dockerClient,
       }
     }
 
+    if (squash) {
+      buildParameters.add(new DockerClient.BuildParam("squash", encodeBuildParam(squash)));
+    }
+
     final DockerClient.BuildParam[] buildParametersArray =
         buildParameters.toArray(new DockerClient.BuildParam[buildParameters.size()]);