Allow to define a custom ImagePullPolicy via configuration (#7520)

Use `pull.policy` in configuration file.

Author: eddumelendez

core/src/main/java/org/testcontainers/images/PullPolicy.java

@@ -1,22 +1,64 @@
 package org.testcontainers.images;
 
+import com.google.common.annotations.VisibleForTesting;
 import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
+import org.testcontainers.utility.TestcontainersConfiguration;
 
 import java.time.Duration;
 
 /**
  * Convenience class with logic for building common {@link ImagePullPolicy} instances.
  *
  */
+@Slf4j
 @UtilityClass
 public class PullPolicy {
 
+    @VisibleForTesting
+    static ImagePullPolicy instance;
+
+    @VisibleForTesting
+    static ImagePullPolicy defaultImplementation = new DefaultPullPolicy();
+
     /**
      * Convenience method for returning the {@link DefaultPullPolicy} default image pull policy
      * @return {@link ImagePullPolicy}
      */
-    public static ImagePullPolicy defaultPolicy() {
-        return new DefaultPullPolicy();
+    public static synchronized ImagePullPolicy defaultPolicy() {
+        if (instance != null) {
+            return instance;
+        }
+
+        String imagePullPolicyClassName = TestcontainersConfiguration.getInstance().getImagePullPolicy();
+        if (imagePullPolicyClassName != null) {
+            log.debug("Attempting to instantiate an ImagePullPolicy with class: {}", imagePullPolicyClassName);
+            ImagePullPolicy configuredInstance;
+            try {
+                configuredInstance =
+                    (ImagePullPolicy) Thread
+                        .currentThread()
+                        .getContextClassLoader()
+                        .loadClass(imagePullPolicyClassName)
+                        .getConstructor()
+                        .newInstance();
+            } catch (Exception e) {
+                throw new IllegalArgumentException(
+                    "Configured ImagePullPolicy could not be loaded: " + imagePullPolicyClassName,
+                    e
+                );
+            }
+
+            log.info("Found configured Image Pull Policy: {}", configuredInstance.getClass());
+
+            instance = configuredInstance;
+        } else {
+            instance = defaultImplementation;
+        }
+
+        log.info("Image pull policy will be performed by: {}", instance);
+
+        return instance;
     }
 
     /**

core/src/main/java/org/testcontainers/images/RemoteDockerImage.java

@@ -35,7 +35,7 @@ public class RemoteDockerImage extends LazyFuture<String> {
     private Future<DockerImageName> imageNameFuture;
 
     @With
-    private ImagePullPolicy imagePullPolicy = PullPolicy.defaultPolicy();
+    ImagePullPolicy imagePullPolicy = PullPolicy.defaultPolicy();
 
     @With
     private ImageNameSubstitutor imageNameSubstitutor = ImageNameSubstitutor.instance();

core/src/main/java/org/testcontainers/utility/TestcontainersConfiguration.java

@@ -213,6 +213,10 @@ public String getImageSubstitutorClassName() {
         return getEnvVarOrProperty("image.substitutor", null);
     }
 
+    public String getImagePullPolicy() {
+        return getEnvVarOrProperty("pull.policy", null);
+    }
+
     public Integer getClientPingTimeout() {
         return Integer.parseInt(getEnvVarOrProperty("client.ping.timeout", "10"));
     }

core/src/test/java/org/testcontainers/images/OverrideImagePullPolicyTest.java

@@ -0,0 +1,54 @@
+package org.testcontainers.images;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.testcontainers.DockerRegistryContainer;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.utility.FakeImagePullPolicy;
+import org.testcontainers.utility.MockTestcontainersConfigurationRule;
+import org.testcontainers.utility.TestcontainersConfiguration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class OverrideImagePullPolicyTest {
+
+    @Rule
+    public MockTestcontainersConfigurationRule config = new MockTestcontainersConfigurationRule();
+
+    private ImagePullPolicy originalInstance;
+
+    private ImagePullPolicy originalDefaultImplementation;
+
+    @Before
+    public void setUp() {
+        this.originalInstance = PullPolicy.instance;
+        this.originalDefaultImplementation = PullPolicy.defaultImplementation;
+        PullPolicy.instance = null;
+        PullPolicy.defaultImplementation = Mockito.mock(ImagePullPolicy.class);
+    }
+
+    @After
+    public void tearDown() {
+        PullPolicy.instance = originalInstance;
+        PullPolicy.defaultImplementation = originalDefaultImplementation;
+    }
+
+    @Test
+    public void simpleConfigurationTest() {
+        Mockito
+            .doReturn(FakeImagePullPolicy.class.getCanonicalName())
+            .when(TestcontainersConfiguration.getInstance())
+            .getImagePullPolicy();
+
+        try (DockerRegistryContainer registry = new DockerRegistryContainer()) {
+            registry.start();
+            GenericContainer<?> container = new GenericContainer<>(registry.createImage()).withExposedPorts(8080);
+            container.start();
+            assertThat(container.getImage().imagePullPolicy).isInstanceOf(FakeImagePullPolicy.class);
+            container.stop();
+        }
+    }
+}

core/src/test/java/org/testcontainers/utility/FakeImagePullPolicy.java

@@ -0,0 +1,12 @@
+package org.testcontainers.utility;
+
+import org.testcontainers.images.AbstractImagePullPolicy;
+import org.testcontainers.images.ImageData;
+
+public class FakeImagePullPolicy extends AbstractImagePullPolicy {
+
+    @Override
+    protected boolean shouldPullCached(DockerImageName imageName, ImageData localImageData) {
+        return false;
+    }
+}

docs/features/advanced_options.md

@@ -31,6 +31,15 @@ It is possible to specify an Image Pull Policy to determine at runtime whether a
 [Custom image pull policy](../../core/src/test/java/org/testcontainers/images/ImagePullPolicyTest.java) inside_block:custom_image_pull_policy
 <!--/codeinclude-->
 
+You can also configure Testcontainers to use your custom implementation by using `pull.policy`
+
+=== "`src/test/resources/testcontainers.properties`"
+    ```text
+    pull.policy=com.mycompany.testcontainers.ExampleImagePullPolicy
+    ```
+
+Please see [the documentation on configuration mechanisms](./configuration.md) for more information.
+
 ## Customizing the container
 
 ### Using docker-java