Issue 185 : Allow one to log process messages to a file

src/main/java/com/spotify/docker/BuildMojo.java

@@ -32,6 +32,7 @@
 import com.spotify.docker.client.AnsiProgressHandler;
 import com.spotify.docker.client.DockerClient;
 import com.spotify.docker.client.DockerException;
+import com.spotify.docker.client.ProgressHandler;
 import com.typesafe.config.Config;
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigFactory;
@@ -52,6 +53,7 @@
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.PrintStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -92,6 +94,12 @@ public class BuildMojo extends AbstractDockerMojo {
    */
   private static final char WINDOWS_SEPARATOR = '\\';
 
+  /**
+   * File to log output
+   */
+  @Parameter(property = "logOutput")
+  private String logOutput;
+
   /**
    * Directory containing the Dockerfile. If the value is not set, the plugin will generate a
    * Dockerfile using the required baseImage value, plus the optional entryPoint, cmd and maintainer
@@ -328,7 +336,11 @@ protected void execute(final DockerClient docker)
       copyResources(destination);
     }
 
-    buildImage(docker, destination, buildParams());
+    if (logOutput == null) {
+      buildImage(docker, destination, buildParams());
+    } else {
+      buildImage(docker, destination, new File(logOutput), buildParams());
+    }
     tagImage(docker, forceTags);
 
     final DockerBuildInformation buildInfo = new DockerBuildInformation(imageName, getLog());
@@ -540,12 +552,45 @@ private void validateParameters() throws MojoExecutionException {
   }
 
   private void buildImage(final DockerClient docker, final String buildDir,
+                          final ProgressHandler progressHandler, 
                           final DockerClient.BuildParam... buildParams)
       throws MojoExecutionException, DockerException, IOException, InterruptedException {
     getLog().info("Building image " + imageName);
-    docker.build(Paths.get(buildDir), imageName, new AnsiProgressHandler(), buildParams);
+    docker.build(Paths.get(buildDir), imageName, progressHandler, buildParams);
     getLog().info("Built " + imageName);
   }
+
+  private void buildImage(final DockerClient docker, final String buildDir,
+                          final File output, 
+                          final DockerClient.BuildParam... buildParams)
+      throws MojoExecutionException, DockerException, IOException, InterruptedException {
+
+    if (output.isDirectory() || (output.exists() && !output.canWrite())) {
+      throw new MojoExecutionException("The specified output file is a directory or cannot "
+                                       + "be written");
+    }
+
+    File parent = output.getParentFile();
+    if (parent.isFile()) {
+      throw new MojoExecutionException("The specified output file's parent is a file");
+    }
+
+    if (!parent.exists() && !parent.mkdirs()) {
+      throw new MojoExecutionException("The specified output file's parent cannot be made a"
+                                       + " directory");
+    }
+
+    try (PrintStream printStream = 
+             new PrintStream(new FileOutputStream(output, true), true, "UTF-8")) {
+        buildImage(docker, buildDir, new AnsiProgressHandler(printStream), buildParams);
+    }
+  }
+
+  private void buildImage(final DockerClient docker, final String buildDir,
+                          final DockerClient.BuildParam... buildParams)
+      throws MojoExecutionException, DockerException, IOException, InterruptedException {
+    buildImage(docker, buildDir, new AnsiProgressHandler(), buildParams);
+  }
 
   private void tagImage(final DockerClient docker, boolean forceTags)
       throws DockerException, InterruptedException, MojoExecutionException {

src/test/java/com/spotify/docker/BuildMojoTest.java

@@ -28,14 +28,17 @@
 import com.spotify.docker.client.AnsiProgressHandler;
 import com.spotify.docker.client.DockerClient;
 import com.spotify.docker.client.DockerClient.BuildParam;
+import com.spotify.docker.client.DockerException;
 import com.spotify.docker.client.ProgressHandler;
 import com.spotify.docker.client.messages.ProgressMessage;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.MojoExecution;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugin.testing.AbstractMojoTestCase;
 import org.apache.maven.project.MavenProject;
+import org.mockito.ArgumentMatcher;
 import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;
 
@@ -56,10 +59,12 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyString;
+import static org.mockito.Matchers.argThat;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 public class BuildMojoTest extends AbstractMojoTestCase {
 
@@ -448,6 +453,112 @@ public void testNoCache() throws Exception {
         eq(BuildParam.noCache()));
   }
 
+  public void testLogOutputToFileButParentIsFile() throws Exception {
+    testLogOutputToFileButFileCannotBeWritten(false);
+  }
+
+  public void testLogOutputToFileButFileIsDirectory() throws Exception {
+    testLogOutputToFileButFileCannotBeWritten(true);
+  }
+
+  public void testLogOutputToFileButFileCannotBeWritten(boolean dir) throws Exception {
+	final File pom = getTestFile("src/test/resources/pom-build-log-output.xml");
+	assertNotNull("Null pom.xml", pom);
+	assertTrue("pom.xml does not exist", pom.exists());
+
+	// Make sure initially the file to be logged does not exist
+	final String outputFileName = "target/docker/outputDir/file-to-log-output.log";
+	final File outputFile = getTestFile(outputFileName);  
+	assertNotNull("Null output file", outputFile);
+	assertFalse("output file already exists", outputFile.exists());
+
+	if (dir) {
+	    // Force it being a directory
+	    assertTrue("Cannot create directory ", outputFile.mkdirs());
+	} else {
+	    // Force parent is be a file
+	    File parent = outputFile.getParentFile();
+	    parent.getParentFile().mkdirs();
+	    assertTrue("Cannot create parent file ", parent.createNewFile());
+	}
+
+	final BuildMojo mojo = setupMojo(pom);
+	final DockerClient docker = mock(DockerClient.class);
+	try {
+	  mojo.execute(docker);
+	  fail("mojo should have thrown exception because output file cannot be written to");
+	} catch (MojoExecutionException e) {
+	  final String message;
+	  if (dir) {
+	      message = "The specified output file is a directory or cannot be written";
+	  } else {
+	      message = "The specified output file's parent is a file";
+	  }
+	  assertTrue(String.format("Exception message should have contained '%s'", message),
+	             e.getMessage().contains(message));
+	}
+  }
+
+  public void testLogOutputToNewFile() throws Exception {
+    testLogOutputToFile(true);
+  }
+
+  public void testLogOutputToExistingFile() throws Exception {
+    testLogOutputToFile(false);
+  }
+
+  private void testLogOutputToFile(boolean newFile) throws Exception {
+	final File pom = getTestFile("src/test/resources/pom-build-log-output.xml");
+	assertNotNull("Null pom.xml", pom);
+	assertTrue("pom.xml does not exist", pom.exists());
+
+	// Make sure initially the file to be logged does not exist
+	final String outputFileName = "target/docker/outputDir/file-to-log-output.log";
+	final File outputFile = getTestFile(outputFileName);  
+	assertNotNull("Null output file", outputFile);
+	assertFalse("output file already exists", outputFile.exists());
+
+	final BuildMojo mojo = setupMojo(pom);
+	final DockerClient docker = mock(DockerClient.class);
+
+	// A matcher that grabs the instantiated AnsiProgressHandler and logs a message
+	final String testMessage = "Testing progress is logged to file";
+	ArgumentMatcher<AnsiProgressHandler> matcher = new ArgumentMatcher<AnsiProgressHandler>() {
+
+		@Override
+		public boolean matches(Object argument) {
+			assertTrue(AnsiProgressHandler.class.isInstance(argument));
+			AnsiProgressHandler handler = AnsiProgressHandler.class.cast(argument);
+			ProgressMessage message = new ProgressMessage();
+			message.status(testMessage);
+			try {
+				handler.progress(message);
+			} catch (DockerException e) {
+				fail("Unexpected error");
+			}
+			return true;
+		}
+
+	};
+
+    if (! newFile) {
+      File parent = outputFile.getParentFile();
+      assertTrue("Cannot create parent directory", parent.exists() || parent.mkdirs());
+      assertTrue("Cannot create output file", outputFile.createNewFile());
+    }
+
+	when(docker.build(eq(Paths.get("target/docker")), eq("busybox"), argThat(matcher))).thenReturn(StringUtils.EMPTY);
+
+    mojo.execute(docker);
+
+	verify(docker).build(eq(Paths.get("target/docker")), eq("busybox"), any(AnsiProgressHandler.class));
+
+	// Make sure output file exists and message is logged
+	assertFileExists(outputFileName);
+	byte[] encoded = Files.readAllBytes(Paths.get(outputFileName));
+	assertEquals(testMessage + System.lineSeparator(), new String(encoded, "UTF-8"));
+  }
+
   private BuildMojo setupMojo(final File pom) throws Exception {
     final MavenProject project = new ProjectStub(pom);
     final MavenSession session = newMavenSession(project);

src/test/resources/pom-build-log-output.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+
+    <name>Docker Maven Plugin Test Pom</name>
+    <groupId>com.spotify</groupId>
+    <artifactId>docker-maven-plugin-test</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>com.spotify</groupId>
+                <artifactId>docker-maven-plugin</artifactId>
+                <version>0.1-SNAPSHOT</version>
+                <configuration>
+                    <!-- we have to supply values for all params because unit testing framework -->
+                    <!-- doesn't set default values even though the are set in mojo-->
+                    <dockerHost>http://host:2375</dockerHost>
+                    <dockerDirectory>src/test/resources/dockerDirectory</dockerDirectory>
+                    <imageName>busybox</imageName>
+                    <!-- test base image is pulled -->
+                    <logOutput>target/docker/outputDir/file-to-log-output.log</logOutput>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>