enhancement lazy env vars

Author: KyleAure

modules/application-server-commons/src/main/java/org/testcontainers/applicationserver/ApplicationServerContainer.java

@@ -18,9 +18,14 @@
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.Future;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -56,6 +61,9 @@ public abstract class ApplicationServerContainer extends GenericContainer<Applic
     // Expected path for Microprofile platforms to query for readiness
     static final String MP_HEALTH_READINESS_PATH = "/health/ready";
 
+    // Lazy environment variables
+    private Map<String, Supplier<String>> lazyEnvVars = new HashMap<>();
+
     //Constructors
 
     public ApplicationServerContainer(@NonNull final Future<String> image) {
@@ -83,6 +91,11 @@ protected void configure() {
         for(MountableFile archive : archives) {
             withCopyFileToContainer(archive, getApplicationInstallDirectory() + extractApplicationName(archive));
         }
+
+        // Add lazy env variables
+        for(Map.Entry<String, Supplier<String>> entry : lazyEnvVars.entrySet()) {
+            withEnv(entry.getKey(), entry.getValue().get());
+        }
     }
 
     @Override
@@ -236,6 +249,27 @@ public ApplicationServerContainer withHttpWaitTimeout(Duration httpWaitTimeout)
         return this;
     }
 
+    /**
+     * An environment variable whose value needs to wait until the configuration stage to be evaluated.
+     * The common use case for this would be to pass inter-container connection data.
+     *
+     * For example an application container often needs to have connection data to a dependent database:
+     * <pre>
+     *     OracleContainer db = new OracleContainer(...).withExposedPorts(1521);
+     *     ApplicationContainer app = new ApplicationContainer(...)
+     *       .withLazyEnv( "oracle.url", () -&gt; db.getJdbcUrl() ) // Need to wait until 'db' container is configured
+     *       .dependsOn(db);
+     * </pre>
+	 *
+     * @param key   - the key
+     * @param valueSupplier - the function that supplies the value
+     * @return self
+     */
+    public ApplicationServerContainer withLazyEnv(String key, Supplier<String> valueSupplier) {
+        lazyEnvVars.put(key, valueSupplier);
+        return this;
+    }
+
     //Getters
 
     /**

modules/liberty/src/test/java/org/testcontainers/containers/LibertyContainerTest.java

@@ -17,13 +17,32 @@
 
 public class LibertyContainerTest {
 
+    /*
+     * Typically application servers have a dependency on a database or other microservice during integration testing
+     * Use a mockServer to ensure dependsOn and lazy env variables work.
+     */
+    public static final DockerImageName mockImage = DockerImageName
+        .parse("mockserver/mockserver")
+        .withTag("mockserver-5.15.0");
+
+    private static GenericContainer<?> dependantService = new GenericContainer<>(mockImage)
+        .withExposedPorts(80,81);
+
+    //The liberty test container
     private static final DockerImageName libertyImage = DockerImageName.parse(LibertyServerContainer.IMAGE)
         .withTag("23.0.0.3-full-java17-openj9");
 
     private static ApplicationServerContainer testContainer = new LibertyServerContainer(libertyImage)
         .withArchvies(createDeployment())
-        .withAppContextRoot("test/app/service/");
-
+        .withAppContextRoot("test/app/service/")
+        .withLazyEnv("mock.port", () ->  "" + dependantService.getMappedPort(80))
+        .dependsOn(dependantService);
+
+    /**
+     * Creates a deployment using Shrinkwrap at runtime.
+     *
+     * @return - the application archive
+     */
     private static Archive<?> createDeployment() {
         return ShrinkWrap.create(WebArchive.class, "test.war")
             .addPackage("org.testcontainers.containers.app");