Make it possible to run TestContainers inside a container

.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1 @@
+distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.3.9/apache-maven-3.3.9-bin.zip

.travis.yml

@@ -19,8 +19,8 @@ before_install:
   - docker pull mysql:5.6
   - docker pull mysql:5.5
   - docker pull postgres:latest
-  - docker pull selenium/standalone-chrome-debug:2.45.0
-  - docker pull selenium/standalone-firefox-debug:2.45.0
+  - docker pull selenium/standalone-chrome-debug:2.52.0
+  - docker pull selenium/standalone-firefox-debug:2.52.0
   - docker pull richnorth/vnc-recorder:latest
   - docker pull nginx:1.9.4
   - docker pull dduportal/docker-compose:1.6.0
@@ -32,6 +32,15 @@ before_install:
 
 script:
   - mvn -B test
+  # Run Docker-in-Docker tests
+  - |
+      DOCKER_HOST=unix:///var/run/docker.sock DOCKER_TLS_VERIFY= docker run --rm \
+      -v "$HOME/.m2":/root/.m2/ \
+      -v /var/run/docker.sock:/var/run/docker.sock \
+      -v "$(pwd)":"$(pwd)" \
+      -w "$(pwd)" \
+      openjdk:8-jre \
+      ./mvnw -B -pl core test -Dtest=*GenericContainerRuleTest
   - mvn -B test -f shade-test/pom.xml
 
 cache:

circle.yml

@@ -18,6 +18,15 @@ dependencies:
 test:
   override:
     - mvn -B test
+    # Run Docker-in-Docker tests
+    - |
+      DOCKER_HOST=unix:///var/run/docker.sock DOCKER_TLS_VERIFY= docker run --rm \
+        -v "$HOME/.m2":/root/.m2/ \
+        -v /var/run/docker.sock:/var/run/docker.sock \
+        -v "$(pwd)":"$(pwd)" \
+        -w "$(pwd)" \
+        openjdk:8-jre \
+        ./mvnw -B -pl core test -Dtest=*GenericContainerRuleTest
     - mvn -B test -f shade-test/pom.xml
   post:
     - mkdir -p $CIRCLE_TEST_REPORTS/junit/

core/src/main/java/org/testcontainers/DockerClientFactory.java

@@ -1,36 +1,35 @@
 package org.testcontainers;
 
 import com.github.dockerjava.api.DockerClient;
-import com.github.dockerjava.api.command.CreateContainerResponse;
+import com.github.dockerjava.api.command.CreateContainerCmd;
 import com.github.dockerjava.api.exception.InternalServerErrorException;
 import com.github.dockerjava.api.exception.NotFoundException;
-import com.github.dockerjava.api.model.Frame;
 import com.github.dockerjava.api.model.Image;
 import com.github.dockerjava.api.model.Info;
 import com.github.dockerjava.api.model.Version;
-import com.github.dockerjava.core.command.LogContainerResultCallback;
 import com.github.dockerjava.core.command.PullImageResultCallback;
-import com.github.dockerjava.core.command.WaitContainerResultCallback;
 
 import lombok.Synchronized;
-import org.slf4j.Logger;
+import lombok.extern.slf4j.Slf4j;
 import org.testcontainers.dockerclient.*;
 
 import java.util.List;
 import java.util.Optional;
+import java.util.function.BiFunction;
+import java.util.function.Consumer;
 
 import static java.util.Arrays.asList;
-import static org.slf4j.LoggerFactory.getLogger;
 
 /**
  * Singleton class that provides initialized Docker clients.
  * <p>
  * The correct client configuration to use will be determined on first use, and cached thereafter.
  */
+@Slf4j
 public class DockerClientFactory {
 
+    private static final String TINY_IMAGE = "alpine:3.2";
     private static DockerClientFactory instance;
-    private static final Logger LOGGER = getLogger(DockerClientFactory.class);
 
     // Cached client configuration
     private DockerClientProviderStrategy strategy;
@@ -80,20 +79,29 @@ public DockerClient client() {
         }
 
         strategy = DockerClientProviderStrategy.getFirstValidStrategy(CONFIGURATION_STRATEGIES);
+
+        log.info("Docker host IP address is {}", strategy.getDockerHostIpAddress());
         DockerClient client = strategy.getClient();
 
         if (!preconditionsChecked) {
             Info dockerInfo = client.infoCmd().exec();
             Version version = client.versionCmd().exec();
             activeApiVersion = version.getApiVersion();
             activeExecutionDriver = dockerInfo.getExecutionDriver();
-            LOGGER.info("Connected to docker: \n" +
+            log.info("Connected to docker: \n" +
                     "  Server Version: " + dockerInfo.getServerVersion() + "\n" +
                     "  API Version: " + activeApiVersion + "\n" +
                     "  Operating System: " + dockerInfo.getOperatingSystem() + "\n" +
                     "  Total Memory: " + dockerInfo.getMemTotal() / (1024 * 1024) + " MB");
 
             checkVersion(version.getVersion());
+
+            List<Image> images = client.listImagesCmd().exec();
+            // Pull the image we use to perform some checks
+            if (images.stream().noneMatch(it -> it.getRepoTags() != null && asList(it.getRepoTags()).contains(TINY_IMAGE))) {
+                client.pullImageCmd(TINY_IMAGE).exec(new PullImageResultCallback()).awaitSuccess();
+            }
+
             checkDiskSpaceAndHandleExceptions(client);
             preconditionsChecked = true;
         }
@@ -121,7 +129,7 @@ private void checkDiskSpaceAndHandleExceptions(DockerClient client) {
         } catch (NotEnoughDiskSpaceException e) {
             throw e;
         } catch (Exception e) {
-            LOGGER.warn("Encountered and ignored error while checking disk space", e);
+            log.warn("Encountered and ignored error while checking disk space", e);
         }
     }
 
@@ -130,44 +138,47 @@ private void checkDiskSpaceAndHandleExceptions(DockerClient client) {
      * @param client an active Docker client
      */
     private void checkDiskSpace(DockerClient client) {
+        DiskSpaceUsage df = runInsideDocker(client, cmd -> cmd.withCmd("df", "-P"), (dockerClient, id) -> {
+                String logResults = dockerClient.logContainerCmd(id)
+                    .withStdOut(true)
+                    .exec(new LogToStringContainerCallback())
+                    .toString();
+
+                return parseAvailableDiskSpace(logResults);
+        });
+
+        log.info("Disk utilization in Docker environment is {} ({} )",
+            df.usedPercent.map(x -> x + "%").orElse("unknown"),
+            df.availableMB.map(x -> x + " MB available").orElse("unknown available"));
+
+        if (df.availableMB.orElseThrow(NotAbleToGetDiskSpaceUsageException::new) < 2048) {
+            log.error("Docker environment has less than 2GB free - execution is unlikely to succeed so will be aborted.");
+            throw new NotEnoughDiskSpaceException("Not enough disk space in Docker environment");
+        }
+    }
 
-        List<Image> images = client.listImagesCmd().exec();
-        if (!images.stream().anyMatch(it -> it.getRepoTags() != null && asList(it.getRepoTags()).contains("alpine:3.2"))) {
-            PullImageResultCallback callback = client.pullImageCmd("alpine:3.2").exec(new PullImageResultCallback());
-            callback.awaitSuccess();
+    public <T> T runInsideDocker(Consumer<CreateContainerCmd> createContainerCmdConsumer, BiFunction<DockerClient, String, T> block) {
+        if (strategy == null) {
+            client();
         }
+        // We can't use client() here because it might create an infinite loop
+        return runInsideDocker(strategy.getClient(), createContainerCmdConsumer, block);
+    }
 
-        CreateContainerResponse createContainerResponse = client.createContainerCmd("alpine:3.2").withCmd("df", "-P").exec();
-        String id = createContainerResponse.getId();
+    private <T> T runInsideDocker(DockerClient client, Consumer<CreateContainerCmd> createContainerCmdConsumer, BiFunction<DockerClient, String, T> block) {
+        CreateContainerCmd createContainerCmd = client.createContainerCmd(TINY_IMAGE);
+        createContainerCmdConsumer.accept(createContainerCmd);
+        String id = createContainerCmd.exec().getId();
 
         client.startContainerCmd(id).exec();
 
-        LogContainerResultCallback callback = client.logContainerCmd(id).withStdOut(true).exec(new LogContainerCallback());
         try {
-
-            WaitContainerResultCallback waitCallback = new WaitContainerResultCallback();
-            client.waitContainerCmd(id).exec(waitCallback);
-            waitCallback.awaitStarted();
-
-            callback.awaitCompletion();
-            String logResults = callback.toString();
-
-            DiskSpaceUsage df = parseAvailableDiskSpace(logResults);
-            LOGGER.info("Disk utilization in Docker environment is {} ({} )", 
-                    df.usedPercent.map(x -> x.toString() + "%").orElse("unknown"), 
-                    df.availableMB.map(x -> x.toString() + " MB available").orElse("unknown available"));
-
-            if (df.availableMB.orElseThrow(NotAbleToGetDiskSpaceUsageException::new) < 2048) {
-                LOGGER.error("Docker environment has less than 2GB free - execution is unlikely to succeed so will be aborted.");
-                throw new NotEnoughDiskSpaceException("Not enough disk space in Docker environment");
-            }
-        } catch (InterruptedException e) {
-            throw new RuntimeException(e);
+            return block.apply(client, id);
         } finally {
             try {
                 client.removeContainerCmd(id).withRemoveVolumes(true).withForce(true).exec();
             } catch (NotFoundException | InternalServerErrorException ignored) {
-
+                log.debug("", ignored);
             }
         }
     }
@@ -231,18 +242,3 @@ private static class NotAbleToGetDiskSpaceUsageException extends RuntimeExceptio
         }
     }
 }
-
-class LogContainerCallback extends LogContainerResultCallback {
-    private final StringBuffer log = new StringBuffer();
-
-    @Override
-    public void onNext(Frame frame) {
-        log.append(new String(frame.getPayload()));
-        super.onNext(frame);
-    }
-
-    @Override
-    public String toString() {
-        return log.toString();
-    }
-}

core/src/main/java/org/testcontainers/dockerclient/DockerClientConfigUtils.java

@@ -1,18 +1,53 @@
 package org.testcontainers.dockerclient;
 
 import com.github.dockerjava.core.DockerClientConfig;
+import lombok.Getter;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang.StringUtils;
+import org.testcontainers.DockerClientFactory;
 
+import java.io.File;
+import java.util.Optional;
+
+@Slf4j
 public class DockerClientConfigUtils {
+
+    // See https://github.com/docker/docker/blob/a9fa38b1edf30b23cae3eade0be48b3d4b1de14b/daemon/initlayer/setup_unix.go#L25
+    public static final boolean IN_A_CONTAINER = new File("/.dockerenv").exists();
+
+    @Getter(lazy = true)
+    private static final Optional<String> detectedDockerHostIp = Optional
+            .of(IN_A_CONTAINER)
+            .filter(it -> it)
+            .map(file -> DockerClientFactory.instance().runInsideDocker(
+                    cmd -> cmd.withCmd("sh", "-c", "ip route|awk '/default/ { print $3 }'"),
+                    (client, id) -> {
+                        try {
+                            return client.logContainerCmd(id)
+                                    .withStdOut(true)
+                                    .exec(new LogToStringContainerCallback())
+                                    .toString();
+                        } catch (Exception e) {
+                            log.warn("Can't parse the default gateway IP", e);
+                            return null;
+                        }
+                    }
+            ))
+            .map(StringUtils::trimToEmpty)
+            .filter(StringUtils::isNotBlank);
+
     public static String getDockerHostIpAddress(DockerClientConfig config) {
-        switch (config.getDockerHost().getScheme()) {
-        case "http":
-        case "https":
-        case "tcp":
-            return config.getDockerHost().getHost();
-        case "unix":
-            return "localhost";
-        default:
-            return null;
-        }
+        return getDetectedDockerHostIp().orElseGet(() -> {
+            switch (config.getDockerHost().getScheme()) {
+                case "http":
+                case "https":
+                case "tcp":
+                    return config.getDockerHost().getHost();
+                case "unix":
+                    return "localhost";
+                default:
+                    return null;
+            }
+        });
     }
 }

core/src/main/java/org/testcontainers/dockerclient/EnvironmentAndSystemPropertyClientProviderStrategy.java

@@ -27,7 +27,6 @@ public void test() throws InvalidConfigurationException {
         }
 
         LOGGER.info("Found docker client settings from environment");
-        LOGGER.info("Docker host IP address is {}", DockerClientConfigUtils.getDockerHostIpAddress(config));
     }
 
     @Override

core/src/main/java/org/testcontainers/dockerclient/LogToStringContainerCallback.java

@@ -0,0 +1,24 @@
+package org.testcontainers.dockerclient;
+
+import com.github.dockerjava.api.model.Frame;
+import com.github.dockerjava.core.command.LogContainerResultCallback;
+
+public class LogToStringContainerCallback extends LogContainerResultCallback {
+    private final StringBuffer log = new StringBuffer();
+
+    @Override
+    public void onNext(Frame frame) {
+        log.append(new String(frame.getPayload()));
+        super.onNext(frame);
+    }
+
+    @Override
+    public String toString() {
+        try {
+            awaitCompletion();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        return log.toString();
+    }
+}

docs/SUMMARY.md

@@ -8,6 +8,7 @@
     * [Usage modes](usage.md#usage-modes)
     * [Maven dependencies](usage.md#maven-dependencies)
     * [Logging](usage.md#logging)
+    * [Docker in Docker](usage/dind.md)
 
 ## Generic containers
 
@@ -52,4 +53,4 @@
 ## 
 * [License](index.md#license)
 * [Attributions](index.md#attributions)
-* [Contributing](index.md#contributing)
+* [Contributing](index.md#contributing)

docs/compatibility.md

@@ -5,7 +5,8 @@
 | Linux - general                     | Docker v1.10              |                                                                                                                                                                                                                                                                                                                                                                    |
 | Linux - Travis CI                   | Docker v1.10              | See [example .travis.yml](https://raw.githubusercontent.com/testcontainers/testcontainers-java/master/.travis.yml) for baseline Travis CI configuration                                                                                                                                                                                                                                                                                     |
 | Linux - Circle CI (LXC driver)      | Docker v1.9.1               | The `exec` feature is not compatible with Circle CI. See [example circle.yml](../circle.yml) for baseline CircleCI configuration                                                                                                                                                                                                                                   |
+| Linux - Docker in Docker            | Docker v1.12              | See [Docker-in-Docker](usage/dind.md) for the detailed configuration                                                                                                                                                                                                                                 |
 | Mac OS X - Docker Toolbox           | Docker Machine v0.8.0  |                                                                                                                                                                                                                                                                                                                                                                    |
 | Mac OS X - Docker for Mac      | 1.12.0          | *Support is best-efforts at present*. `getTestHostIpAddress()` is [not currently supported](https://github.com/testcontainers/testcontainers-java/issues/166) due to limitations in Docker for Mac. |
 | Windows - Docker Toolbox            |                             | *Support is limited at present and this is not currently tested on a regular basis*.                                                                                                                                                                                                                                                                               |
-| Windows - Docker for Windows Beta   |                             | *Not currently supported*.                                                                                                                                                                                                                                                                                                                                         |
+| Windows - Docker for Windows Beta   |                             | *Not currently supported*.                                                                                                                                                                                                                                                                                                                                         |

docs/usage.md

@@ -19,6 +19,7 @@ Testcontainers will try to connect to a Docker daemon using the following strate
 	* `DOCKER_TLS_VERIFY=1`
 	* `DOCKER_CERT_PATH=~/.docker`
 * If Docker Machine is installed, the docker machine environment for the *first* machine found. Docker Machine needs to be on the PATH for this to succeed.
+* If you're going to run your tests inside a container, please read [Docker in Docker](usage/dind.md) first.
 
 ### Usage modes
 
@@ -97,4 +98,4 @@ should be included in your classpath to show a reasonable level of log output:
     <logger name="com.github.dockerjava" level="WARN"/>
     <logger name="org.zeroturnaround.exec" level="WARN"/>
 </configuration>
-```
+```