[Apache Atlas] Atlas 架构设计及源代码简单分析

Apache Atlas 架构图

Atlas 支持多数据源接入:Hive、HBase、Storm等

Type System

Type

Atlas 中定义了一些元数据类型

── AtlasBaseTypeDef

  │   ├── AtlasEnumDef

  │   └── AtlasStructDef

  │       ├── AtlasBusinessMetadataDef

  │       ├── AtlasClassificationDef

  │       ├── AtlasEntityDef

  │       └── AtlasRelationshipDef

  ├── AtlasStructType

  │   ├── AtlasBusinessMetadataType

  │   ├── AtlasClassificationType

  │   ├── AtlasRelationshipType

  │   └── AtlasEntityType

  │       └── AtlasRootEntityType

  ├── AtlasType

  │   ├── AtlasArrayType

  │   ├── AtlasBigDecimalType

  │   ├── AtlasBigIntegerType

  │   ├── AtlasByteType

  │   ├── AtlasDateType

  │   ├── AtlasDoubleType

  │   ├── AtlasEnumType

  │   ├── AtlasFloatType

  │   ├── AtlasIntType

  │   ├── AtlasLongType

  │   ├── AtlasMapType

  │   ├── AtlasObjectIdType

  │   ├── AtlasShortType

  │   ├── AtlasStringType

  │   └── AtlasStructType

  │       ├── AtlasBusinessMetadataType

  │       ├── AtlasClassificationType

  │       ├── AtlasEntityType

  │       └── AtlasRelationshipType

  ├── AtlasTypeDefStore

  │   └── AtlasTypeDefGraphStore

  │       └── AtlasTypeDefGraphStoreV2

  └── StructTypeDefinition

      └── HierarchicalTypeDefinition

          ├── ClassTypeDefinition

          └── TraitTypeDefinition

Entity

Entity 是基于类型的具体实现

AtlasEntity

  ├── AtlasEntityExtInfo

  │   ├── AtlasEntitiesWithExtInfo

  │   └── AtlasEntityWithExtInfo

  ├── AtlasEntityStore

  │   └── AtlasEntityStoreV2

  ├── AtlasEntityStream

  │   └── AtlasEntityStreamForImport

  ├── AtlasEntityType

  │   └── AtlasRootEntityType

  └── IAtlasEntityChangeNotifier

      ├── AtlasEntityChangeNotifier

      └── EntityChangeNotifierNop

Attributes

针对模型定义属性

AtlasAttributeDef

      └── AtlasRelationshipAttributeDef

AtlasAttributeDef 属性字段:

private String                   name;

private String                   typeName;

private boolean                  isOptional;

private Cardinality              cardinality;

private int                      valuesMinCount;

private int                      valuesMaxCount;

private boolean                  isUnique;

private boolean                  isIndexable;

private boolean                  includeInNotification;

private String                   defaultValue;

private String                   description;

private int                      searchWeight = DEFAULT_SEARCHWEIGHT;

private IndexType                indexType    = null;

private List<AtlasConstraintDef> constraints;

private Map<String, String>      options;

private String                   displayName;

具体实现：

db:

    "name":        "db",

    "typeName":    "hive_db",

    "isOptional":  false,

    "isIndexable": true,

    "isUnique":    false,

    "cardinality": "SINGLE"

columns:

    "name":        "columns",

    "typeName":    "array<hive_column>",

    "isOptional":  optional,

    "isIndexable": true,

    “isUnique":    false,

    "constraints": [ { "type": "ownedRef" } ]

isComposite - 是否复合
isIndexable - 是否索引
isUnique - 是否唯一
multiplicity - 指示此属性是（必需的／可选的／还是可以是多值）的

System specific types and their significance

Referenceable

This type represents all entities that can be searched for using a unique attribute called qualifiedName.

  ├── Referenceable

  ├── ReferenceableDeserializer

  ├── ReferenceableSerializer

  └── V1SearchReferenceableSerializer

Hooks

以Hive元信息采集为例分析采集过程:

全量导入

import-hive.sh

"${JAVA_BIN}" ${JAVA_PROPERTIES} -cp "${CP}"

org.apache.atlas.hive.bridge.HiveMetaStoreBridge $IMPORT_ARGS

importTables

  └── importDatabases        [addons/hive-bridge/src/main/java/org/apache/atlas/hive/bridge/HiveMetaStoreBridge.java +295]

      └── importHiveMetadata [addons/hive-bridge/src/main/java/org/apache/atlas/hive/bridge/HiveMetaStoreBridge.java +289]

上面是调用过程：

importTables -> importTable --> registerInstances

AtlasEntitiesWithExtInfo ret = null;

EntityMutationResponse   response        = atlasClientV2.createEntities(entities);

List<AtlasEntityHeader>  createdEntities = response.getEntitiesByOperation(EntityMutations.EntityOperation.CREATE);

if (CollectionUtils.isNotEmpty(createdEntities)) {

    ret = new AtlasEntitiesWithExtInfo();

    for (AtlasEntityHeader createdEntity : createdEntities) {

        AtlasEntityWithExtInfo entity = atlasClientV2.getEntityByGuid(createdEntity.getGuid());

        ret.addEntity(entity.getEntity());

        if (MapUtils.isNotEmpty(entity.getReferredEntities())) {

            for (Map.Entry<String, AtlasEntity> entry : entity.getReferredEntities().entrySet()) {

                ret.addReferredEntity(entry.getKey(), entry.getValue());

            }

        }

        LOG.info("Created {} entity: name={}, guid={}", entity.getEntity().getTypeName(), entity.getEntity().getAttribute(ATTRIBUTE_QUALIFIED_NAME), entity.getEntity().getGuid());

    }

}

通过Http Post 的请求将库表数据更新至Atlas

atlasClientV2有很多Http接口

Atlas HTTP 客户端API:

实时监听

HiveHook implements ExecuteWithHookContext

ExecuteWithHookContext is a new interface that the Pre/Post Execute Hook can run with the HookContext.

实现run()方法来对Hive 相关事件做处理

Hive相关事件:

BaseHiveEvent

      ├── AlterTableRename

      ├── CreateHiveProcess

      ├── DropDatabase

      ├── DropTable

      ├── CreateDatabase

      │   └── AlterDatabase

      └── CreateTable

          └── AlterTable

              └── AlterTableRenameCol

以create database 为例分析流程:

//处理Hook 上下文信息

AtlasHiveHookContext context =

new AtlasHiveHookContext(this, oper, hookContext, getKnownObjects(), isSkipTempTables());

//建库事件处理,提取相关库信息

event = new CreateDatabase(context);

if (event != null) {

    final UserGroupInformation ugi = hookContext.getUgi() == null ? Utils.getUGI() : hookContext.getUgi();

    super.notifyEntities(ActiveEntityFilter.apply(event.getNotificationMessages()), ugi);

}

public enum HookNotificationType {

    TYPE_CREATE, TYPE_UPDATE, ENTITY_CREATE, ENTITY_PARTIAL_UPDATE, ENTITY_FULL_UPDATE, ENTITY_DELETE,

    ENTITY_CREATE_V2, ENTITY_PARTIAL_UPDATE_V2, ENTITY_FULL_UPDATE_V2, ENTITY_DELETE_V2

}

//操作用户获取

if (context.isMetastoreHook()) {

    try {

        ugi = SecurityUtils.getUGI();

    } catch (Exception e) {

        //do nothing

    }

} else {

    ret = getHiveUserName();

    if (StringUtils.isEmpty(ret)) {

        ugi = getUgi();

    }

}

if (ugi != null) {

    ret = ugi.getShortUserName();

}

if (StringUtils.isEmpty(ret)) {

    try {

        ret = UserGroupInformation.getCurrentUser().getShortUserName();

    } catch (IOException e) {

        LOG.warn("Failed for UserGroupInformation.getCurrentUser() ", e);

        ret = System.getProperty("user.name");

    }

}

主要:

获取实体信息, 传递Hook message的类型、操作用户

notifyEntities 可以看出其他组件HBase、impala也会调用该方法进行消息的发送

public static void notifyEntities(List<HookNotification> messages, UserGroupInformation ugi, int maxRetries) {

    if (executor == null) { // send synchronously

        notifyEntitiesInternal(messages, maxRetries, ugi, notificationInterface, logFailedMessages, failedMessagesLogger);

    } else {

        executor.submit(new Runnable() {

            @Override

            public void run() {

                notifyEntitiesInternal(messages, maxRetries, ugi, notificationInterface, logFailedMessages, failedMessagesLogger);

            }

        });

    }

}

消息通知框架:

NotificationInterface

      ├── AtlasFileSpool

      └── AbstractNotification

          ├── KafkaNotification

          └── Spooler

数据写入Kafka中:

@Override

public void sendInternal(NotificationType notificationType, List<String> messages) throws NotificationException {

    KafkaProducer producer = getOrCreateProducer(notificationType);

    sendInternalToProducer(producer, notificationType, messages);

}

根据NotificationType写入指定topic 中:

private static final Map<NotificationType, String> PRODUCER_TOPIC_MAP = new HashMap<NotificationType, String>() {

    {

        put(NotificationType.HOOK, ATLAS_HOOK_TOPIC);

        put(NotificationType.ENTITIES, ATLAS_ENTITIES_TOPIC);

    }

};

NOTIFICATION_HOOK_TOPIC_NAME("atlas.notification.hook.topic.name", "ATLAS_HOOK"),

NOTIFICATION_ENTITIES_TOPIC_NAME("atlas.notification.entities.topic.name", "ATLAS_ENTITIES"),

数据主要写入两个Topic中: ATLAS_ENTITIES、ATLAS_HOOK

ATLAS_HOOK是写入Hook事件消息, 创建库的事件元数据信息会写入该Topic中

如何唯一确定一个库：

public String getQualifiedName(Database db) {

    return getDatabaseName(db) + QNAME_SEP_METADATA_NAMESPACE + getMetadataNamespace();

}

dbName@clusterName 确定唯一性

外延应用

一个基于Hive hook 实现Impala 元数据刷新的用例:

AutoRefreshImpala：https://github.com/Observe-secretly/AutoRefreshImpala

参考

[1] Apache Atlas – Data Governance and Metadata framework for Hadoop

[2] Apache Atlas 源码

巴特西