Fix for #292: Skip plugin execution when a Dockerfile is not present

docs/usage.md

@@ -35,6 +35,7 @@ mvn clean package -Ddockerfile.skip
 | `dockerfile.contextDirectory` | Directory containing the Dockerfile to build. | yes | none |
 | `dockerfile.repository` | The repository to name the built image | no | none |
 | `dockerfile.tag` | The tag to apply when building the Dockerfile, which is appended to the repository. | no | latest |
+| `dockerfile.failedOnMissingDockerfile` | Failed maven build when there is no default Dockerfile in the project/module. | no | true
 | `dockerfile.build.pullNewerImage` | Updates base images automatically. | no | true |
 | `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 |

plugin/src/it/multi-module/c/pom.xml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  -/-/-
+  Dockerfile Maven Plugin
+  %%
+  Copyright (C) 2015 - 2016 Spotify AB
+  %%
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+  -\-\-
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>com.spotify.it</groupId>
+    <artifactId>multi-module</artifactId>
+    <version>1.0-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>c</artifactId>
+
+  <description>The third module</description>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>@project.groupId@</groupId>
+        <artifactId>@project.artifactId@</artifactId>
+        <version>@project.version@</version>
+        <executions>
+          <execution>
+            <id>default</id>
+            <goals>
+              <goal>build</goal>
+            </goals>
+            <configuration>
+              <repository>test/multi-module-c</repository>
+              <tag>unstable</tag>
+              <failedOnMissingDockerfile>false</failedOnMissingDockerfile>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

plugin/src/it/multi-module/pom.xml

@@ -33,6 +33,7 @@
   <modules>
     <module>a</module>
     <module>b</module>
+    <module>c</module>
   </modules>
 
   <build>

plugin/src/it/multi-module/verify.groovy

@@ -28,3 +28,6 @@ assert tagFile.text == "unstable\n"
 
 File imageNameFile = new File(basedir, "b/target/docker-info-deps/META-INF/docker/com.spotify.it/a/image-name")
 assert imageNameFile.text == "test/multi-module-a:unstable\n"
+
+String buildLog = new File("${basedir}/build.log").getText("UTF-8")
+assert buildLog.contains("docker-maven plugin execution is skipped for:")

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

@@ -91,6 +91,12 @@ public class BuildMojo extends AbstractDockerMojo {
   @Parameter(property = "dockerfile.build.skip", defaultValue = "false")
   private boolean skipBuild;
 
+  /**
+   * Failed the build when Default docker file is not present in the context directory.
+   */
+  @Parameter(property = "dockerfile.build.failedOnMissingDockerfile", defaultValue = "true")
+  private boolean failedOnMissingDockerfile;
+
   /**
    * Updates base images automatically.
    */
@@ -132,6 +138,24 @@ public void execute(DockerClient dockerClient)
     if (dockerfile != null) {
       dockerfilePath = dockerfile.toPath();
     }
+
+    log.info("Path(dockerfile): " + dockerfilePath);
+    log.info("Path(contextDirectory): " + contextDirectory.toPath());
+
+    if (dockerfilePath == null
+            && !Files.exists(contextDirectory.toPath().resolve("Dockerfile"))
+            && !Files.exists(contextDirectory.toPath().resolve("dockerfile"))) {
+      // user did not override the default value
+      log.warn("Missing Dockerfile in context directory: " + contextDirectory.toPath());
+      if (failedOnMissingDockerfile) {
+        throw new MojoFailureException("Missing Dockerfile in context directory: "
+                + contextDirectory);
+      } else {
+        log.warn("docker-maven plugin execution is skipped for: " + contextDirectory.toPath());
+        return;
+      }
+    }
+
     final String imageId = buildImage(
         dockerClient, log, verbose, contextDirectory.toPath(), dockerfilePath, repository, tag, 
         pullNewerImage, noCache, buildArgs, cacheFrom, squash);
@@ -262,18 +286,6 @@ private static void requireValidDockerFilePath(@Nonnull Log log,
                                                  @Nullable Path dockerfile)
       throws MojoFailureException {
 
-    log.info("Path(dockerfile): " + dockerfile);
-    log.info("Path(contextDirectory): " + contextDirectory);
-
-    if (dockerfile == null
-            && !Files.exists(contextDirectory.resolve("Dockerfile"))
-            && !Files.exists(contextDirectory.resolve("dockerfile"))) {
-      // user did not override the default value
-      log.error("Missing Dockerfile in context directory: " + contextDirectory);
-      throw new MojoFailureException("Missing Dockerfile in context directory: "
-          + contextDirectory);
-    }
-
     if (dockerfile != null) {
       if (!Files.exists(dockerfile)) {
         log.error("Missing Dockerfile at " + dockerfile);