#198 : Expose container information as Docker properties.

E.g. docker.container.<alias>.ip exposes the internal IP address of a docker container. Fixes #198

doc/changelog.md

@@ -8,9 +8,12 @@
   - Move `dockerFileDir` to topLevel `<build>` and introduced `dockerFile` directive
    `build>assembly>dockerFileDir` is now deprecated and will be removed.
   - Add new lifecycles "docker" (build + run), "docker-build" (build only) and 
-    "docker-tar" (creating source) 
+    "docker-tar" (creating source)  (#433)
   - Add `docker:run` as an alias to `docker:start`
-
+  - Expose certain container properties also as Maven properties. By default
+    the format is `docker.container.<alias>.ip` for the internal IP address of container with alias `<alias>`.
+    (#198)
+
 * **0.14.2**
   - Introduce a mode `try` for `<cleanup>` so that an image gets removed if not being still used. 
     This is the default now, which should be close enough to `true` (except that it won't fail the build

doc/manual/docker-start.md

@@ -12,7 +12,19 @@ CTRL-C is pressed. That similar to the option `-i` for `docker run`. This will a
  you can see what is happening within the container. Also, after stopping with CTRL-C, the container is stopped (but 
  not removed so that you can make postmortem analysis).
 
-The `<run>` configuration knows the following sub elements:
+By default container specific properties are exposed as Maven properties. These properties have the format
+`docker.container.`*<alias>*`.`*<prop>* where *alias* is the name of the container (see below) and *<prop>* is one of
+the following container properties:
+
+* **ip** : The internal IP address of the container.
+
+For example the Maven property `docker.container.tomcat.ip` would container the Docker internal IP for a container with 
+an alias "tomcat". You can set the global configuration **exposeContainerInfo** to an empty string to not expose container 
+information that way or to a string for an other prefix than `docker.container`.
+
+#### <run> Configuration
+
+The `<run>` configuration section knows the following sub elements:
 
 * **capAdd** a list of `add` elements to specify kernel parameters to add to
   the container.

samples/data-jolokia-demo/pom.xml

@@ -472,7 +472,7 @@
     </profile>
 
     <profile>
-      <id>post-integration-test</id>
+      <id>properties</id>
       <build>
         <plugins>
           <plugin>
@@ -489,7 +489,8 @@
             </executions>
             <configuration>
               <echos>
-                <echo>============= Post Integration Test ========================</echo>
+                <echo>============= Props  =============</echo>
+                <echo>IP : ${docker.container.server.ip}</echo>
               </echos>
             </configuration>
           </plugin>

samples/dockerignore/pom.xml

@@ -16,8 +16,8 @@
 
   <artifactId>dmp-sample-dockerignore</artifactId>
   <version>0.15.0-SNAPSHOT</version>
-  <packaging>docker-tar</packaging>
-  
+  <packaging>docker-build</packaging>
+
   <build>
     <plugins>
       <plugin>

src/main/java/io/fabric8/maven/docker/StartMojo.java

@@ -9,7 +9,9 @@
  */
 
 import java.io.IOException;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
 import java.util.regex.Pattern;
 
 import io.fabric8.maven.docker.access.DockerAccess;
@@ -32,6 +34,7 @@
 import org.codehaus.plexus.util.StringUtils;
 
 
+
 /**
  * Goal for creating and starting a docker container. This goal evaluates the image configuration
  *
@@ -46,9 +49,25 @@ public class StartMojo extends AbstractDockerMojo {
     @Parameter(property = "docker.pull.registry")
     private String pullRegistry;
 
-    // whether to block during to start. Set it via Sysem property docker.follow
+    // whether to block during to start. Set it via System property docker.follow
     private boolean follow;
 
+    /**
+     * Expose container information like the internal IP as Maven properties which
+     * can be reused in the build information. The value of this property is the prefix
+     * used for the properties. The default prefix is "docker.container". Only information
+     * of images having an alias are exposed and have the format <code>&lt;prefix&gt;.&lt;alias&gt;.&lt;property&gt;</code>.
+     * (e.g. <code>docker.container.mycontainer.ip</code>
+     * The following properties are currently supported:
+     * <ul>
+     *   <li><strong>ip</strong> : the container's internal IP address as chosen by Docker</li>
+     * </ul>
+     *
+     * If set to an empty string, no properties are exposed.
+     */
+    @Parameter(property = "docker.exposeContainerInfo")
+    private String exposeContainerProps = "docker.container";
+
     /**
      * {@inheritDoc}
      */
@@ -97,6 +116,9 @@ public synchronized void executeInternal(final ServiceHub hub) throws DockerAcce
                 if (waitConfig != null && waitConfig.getExec() != null && waitConfig.getExec().getPostStart() != null) {
                     runService.execInContainer(containerId, waitConfig.getExec().getPostStart(), imageConfig);
                 }
+
+                // Expose container info as properties
+                exposeContainerProps(hub.getQueryService(), containerId,imageConfig.getAlias());
             }
             if (follow) {
                 runService.addShutdownHookForStoppingContainers(keepContainer,removeVolumes);
@@ -271,4 +293,22 @@ protected boolean showLogs(ImageConfiguration imageConfig) {
         return false;
     }
 
+    private void exposeContainerProps(QueryService queryService, String containerId, String alias)
+        throws DockerAccessException {
+        if (StringUtils.isNotEmpty(exposeContainerProps) && StringUtils.isNotEmpty(alias)) {
+            Container container = queryService.getContainer(containerId);
+            Properties props = project.getProperties();
+            String ip = container.getIPAddress();
+            if (StringUtils.isNotEmpty(ip)) {
+                String key = addDot(exposeContainerProps) + addDot(alias) + "ip";
+                props.put(key, ip);
+            }
+        }
+    }
+
+    private String addDot(String part) {
+        return part.endsWith(".") ? part : part + ".";
+    }
+
+
 }