Implement Cassandra support

modules/cassandra/build.gradle

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+description = "TestContainers :: Cassandra"
+
+dependencies {
+    compile project(":database-commons")
+    compile "com.datastax.cassandra:cassandra-driver-core:3.4.0"
+
+    /*Netty dependency to override datastax netty transitive dependency that conflicts with netty from
+        com.github.docker-java*/
+    testCompile "io.netty:netty-handler:4.1.11.Final"
+}

modules/cassandra/src/main/java/org/testcontainers/containers/CassandraContainer.java

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+package org.testcontainers.containers;
+
+import com.datastax.driver.core.Cluster;
+import com.github.dockerjava.api.command.InspectContainerResponse;
+import org.apache.commons.io.IOUtils;
+import org.testcontainers.containers.delegate.CassandraDatabaseDelegate;
+import org.testcontainers.delegate.DatabaseDelegate;
+import org.testcontainers.ext.ScriptUtils;
+import org.testcontainers.ext.ScriptUtils.ScriptLoadException;
+import org.testcontainers.utility.MountableFile;
+
+import javax.script.ScriptException;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.Optional;
+
+/**
+ * Cassandra container
+ *
+ * Supports 2.x and 3.x Cassandra versions
+ *
+ * @author Eugeny Karpov
+ */
+public class CassandraContainer<SELF extends CassandraContainer<SELF>> extends GenericContainer<SELF> {
+
+    public static final String IMAGE = "cassandra";
+    public static final Integer CQL_PORT = 9042;
+    private static final String CONTAINER_CONFIG_LOCATION = "/etc/cassandra";
+    private static final String USERNAME = "cassandra";
+    private static final String PASSWORD = "cassandra";
+
+    private String configLocation;
+    private String initScriptPath;
+
+    public CassandraContainer() {
+        this(IMAGE + ":latest");
+    }
+
+    public CassandraContainer(String dockerImageName) {
+        super(dockerImageName);
+        addExposedPort(CQL_PORT);
+        setStartupAttempts(3);
+    }
+
+    @Override
+    protected void configure() {
+        optionallyMapResourceParameterAsVolume(CONTAINER_CONFIG_LOCATION, configLocation);
+    }
+
+    @Override
+    protected void containerIsStarted(InspectContainerResponse containerInfo) {
+        runInitScriptIfRequired();
+    }
+
+    /**
+     * Load init script content and apply it to the database if initScriptPath is set
+     */
+    private void runInitScriptIfRequired() {
+        if (initScriptPath != null) {
+            try {
+                URL resource = Thread.currentThread().getContextClassLoader().getResource(initScriptPath);
+                if (resource == null) {
+                    logger().warn("Could not load classpath init script: {}", initScriptPath);
+                    throw new ScriptLoadException("Could not load classpath init script: " + initScriptPath + ". Resource not found.");
+                }
+                String cql = IOUtils.toString(resource, StandardCharsets.UTF_8);
+                DatabaseDelegate databaseDelegate = getDatabaseDelegate();
+                ScriptUtils.executeDatabaseScript(databaseDelegate, initScriptPath, cql);
+            } catch (IOException e) {
+                logger().warn("Could not load classpath init script: {}", initScriptPath);
+                throw new ScriptLoadException("Could not load classpath init script: " + initScriptPath, e);
+            } catch (ScriptException e) {
+                logger().error("Error while executing init script: {}", initScriptPath, e);
+                throw new ScriptUtils.UncategorizedScriptException("Error while executing init script: " + initScriptPath, e);
+            }
+        }
+    }
+
+    /**
+     * Map (effectively replace) directory in Docker with the content of resourceLocation if resource location is not null
+     *
+     * Protected to allow for changing implementation by extending the class
+     *
+     * @param pathNameInContainer path in docker
+     * @param resourceLocation    relative classpath to resource
+     */
+    protected void optionallyMapResourceParameterAsVolume(String pathNameInContainer, String resourceLocation) {
+        Optional.ofNullable(resourceLocation)
+                .map(MountableFile::forClasspathResource)
+                .ifPresent(mountableFile -> addFileSystemBind(mountableFile.getResolvedPath(), pathNameInContainer, BindMode.READ_WRITE));
+    }
+
+    /**
+     * Initialize Cassandra with the custom overridden Cassandra configuration
+     * <p>
+     * Be aware, that Docker effectively replaces all /etc/cassandra content with the content of config location, so if
+     * Cassandra.yaml in configLocation is absent or corrupted, then Cassandra just won't launch
+     *
+     * @param configLocation relative classpath with the directory that contains cassandra.yaml and other configuration files
+     */
+    public SELF withConfigurationOverride(String configLocation) {
+        this.configLocation = configLocation;
+        return self();
+    }
+
+    /**
+     * Initialize Cassandra with init CQL script
+     * <p>
+     * CQL script will be applied after container is started (see using WaitStrategy)
+     *
+     * @param initScriptPath relative classpath resource
+     */
+    public SELF withInitScript(String initScriptPath) {
+        this.initScriptPath = initScriptPath;
+        return self();
+    }
+
+    /**
+     * Get username
+     *
+     * By default Cassandra has authenticator: AllowAllAuthenticator in cassandra.yaml
+     * If username and password need to be used, then authenticator should be set as PasswordAuthenticator
+     * (through custom Cassandra configuration) and through CQL with default cassandra-cassandra credentials
+     * user management should be modified
+     */
+    public String getUsername() {
+        return USERNAME;
+    }
+
+    /**
+     * Get password
+     *
+     * By default Cassandra has authenticator: AllowAllAuthenticator in cassandra.yaml
+     * If username and password need to be used, then authenticator should be set as PasswordAuthenticator
+     * (through custom Cassandra configuration) and through CQL with default cassandra-cassandra credentials
+     * user management should be modified
+     */
+    public String getPassword() {
+        return PASSWORD;
+    }
+
+    /**
+     * Get configured Cluster
+     *
+     * Can be used to obtain connections to Cassandra in the container
+     */
+    public Cluster getCluster() {
+        return Cluster.builder()
+                .addContactPoint(this.getContainerIpAddress())
+                .withPort(this.getMappedPort(CQL_PORT))
+                .build();
+    }
+
+    private DatabaseDelegate getDatabaseDelegate() {
+        return new CassandraDatabaseDelegate(this);
+    }
+}

modules/cassandra/src/main/java/org/testcontainers/containers/delegate/CassandraDatabaseDelegate.java

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+package org.testcontainers.containers.delegate;
+
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.exceptions.DriverException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.testcontainers.containers.CassandraContainer;
+import org.testcontainers.delegate.AbstractDatabaseDelegate;
+import org.testcontainers.exception.ConnectionCreationException;
+import org.testcontainers.ext.ScriptUtils.ScriptStatementFailedException;
+
+/**
+ * Cassandra database delegate
+ *
+ * @author Eugeny Karpov
+ */
+@Slf4j
+@RequiredArgsConstructor
+public class CassandraDatabaseDelegate extends AbstractDatabaseDelegate<Session> {
+
+    private final CassandraContainer container;
+
+    @Override
+    protected Session createNewConnection() {
+        try {
+            return container.getCluster()
+                    .newSession();
+        } catch (DriverException e) {
+            log.error("Could not obtain cassandra connection");
+            throw new ConnectionCreationException("Could not obtain cassandra connection", e);
+        }
+    }
+
+    @Override
+    public void execute(String statement, String scriptPath, int lineNumber, boolean continueOnError, boolean ignoreFailedDrops) {
+        try {
+            ResultSet result = getConnection().execute(statement);
+            if (result.wasApplied()) {
+                log.debug("Statement {} was applied", statement);
+            } else {
+                throw new ScriptStatementFailedException(statement, lineNumber, scriptPath);
+            }
+        } catch (DriverException e) {
+            throw new ScriptStatementFailedException(statement, lineNumber, scriptPath, e);
+        }
+    }
+
+    @Override
+    protected void closeConnectionQuietly(Session session) {
+        try {
+            session.getCluster().close();
+        } catch (Exception e) {
+            log.error("Could not close cassandra connection", e);
+        }
+    }
+}

modules/cassandra/src/main/java/org/testcontainers/containers/wait/CassandraQueryWaitStrategy.java

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+package org.testcontainers.containers.wait;
+
+import org.jetbrains.annotations.NotNull;
+import org.rnorth.ducttape.TimeoutException;
+import org.testcontainers.containers.CassandraContainer;
+import org.testcontainers.containers.ContainerLaunchException;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.containers.delegate.CassandraDatabaseDelegate;
+import org.testcontainers.delegate.DatabaseDelegate;
+
+import java.util.concurrent.TimeUnit;
+
+import static org.rnorth.ducttape.unreliables.Unreliables.retryUntilSuccess;
+
+/**
+ * Waits until Cassandra returns its version
+ *
+ * @author Eugeny Karpov
+ */
+public class CassandraQueryWaitStrategy extends GenericContainer.AbstractWaitStrategy {
+
+    private static final String SELECT_VERSION_QUERY = "SELECT release_version FROM system.local";
+    private static final String TIMEOUT_ERROR = "Timed out waiting for Cassandra to be accessible for query execution";
+
+    @Override
+    protected void waitUntilReady() {
+        CassandraContainer cassandraContainer = getCassandraContainer();
+
+        // execute select version query until success or timeout
+        try {
+            retryUntilSuccess((int) startupTimeout.getSeconds(), TimeUnit.SECONDS, () -> {
+                getRateLimiter().doWhenReady(() -> {
+                    try (DatabaseDelegate databaseDelegate = getDatabaseDelegate(cassandraContainer)) {
+                        databaseDelegate.execute(SELECT_VERSION_QUERY, "", 1, false, false);
+                    }
+                });
+                return true;
+            });
+        } catch (TimeoutException e) {
+            throw new ContainerLaunchException(TIMEOUT_ERROR);
+        }
+    }
+
+    /**
+     * Cast generic container to Cassandra container or throw exception
+     *
+     * @throws UnsupportedOperationException if containter is null or is not Cassandra container
+     */
+    @NotNull
+    private CassandraContainer getCassandraContainer() {
+        if (container instanceof CassandraContainer) {
+            return (CassandraContainer) container;
+        } else {
+            throw new IllegalStateException("Unsupported container type");
+        }
+    }
+
+    private DatabaseDelegate getDatabaseDelegate(CassandraContainer container) {
+        return new CassandraDatabaseDelegate(container);
+    }
+}