前言

本文基于Flink1.11.2 的稳定版本探讨flink实时写入Hive的技术可行性,下面是个本地测试的案例可供参考。

一、Flink ETL SQL化思路

我们有很多实时数据是存储在kafka中,如何按照分区低延迟的高效存储在Hive数仓中以便于近实时分析是我们现在一个普遍诉求。
这里暂不涉及修改的记录,使用场景局限在某些日志类型,如涉及更新修改的应考察数据湖方案。Flink在1.11版本中已经实现了流批统一,

Table API & SQL 统一了 DataStream API 和 DataSet API ,如没有特殊业务场景,个人觉得可以多使用 Table API  &SQL . 我们知道

TableEnvironment 是 flink 中集成 Table API 和 SQL 的核心概念,所有对表的操作都基于 TableEnvironment

  1. 注册catalog
  2. 在内部 catalog 中注册表
  3. 执行 SQL 查询
  4. 注册用户自定义函数
  5. 将 DataStream 或 DataSet 转换为表等

     

二、初始化执行环境

1.引入相关依赖(maven)

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.zm</groupId>
    <artifactId>FlinkETL</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>Flink Quickstart Job</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <flink.version>1.11.2</flink.version>
        <hive.version>2.1.1</hive.version>
        <java.version>1.8</java.version>
        <scala.binary.version>2.11</scala.binary.version>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- Apache Flink dependencies -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-json</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_2.11</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <!--使用Java编程语言支持DataStream / DataSet API的Table&SQL API-->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-api-java-bridge_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <!--必须将以下依赖项添加到项目中才能使用Table API和SQL来定义管道-->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-planner_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-planner-blink_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <!--通过自定义函数,格式等扩展表生态系统的通用模块-->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-common</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>


        <!-- Flink kafka connector: kafka版本大于1.0.0可以直接使用通用的连接器 -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-kafka_2.11</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-shaded-hadoop-2-uber</artifactId>
            <version>2.7.5-10.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-hive_2.11</artifactId>
            <version>${flink.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-api-java-bridge_2.11</artifactId>
            <version>1.11.2</version>
            <scope>provided</scope>
        </dependency>

        <!-- Hive Dependency -->
        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-exec</artifactId>
            <version>${hive.version}</version>
            <scope>provided</scope>
        </dependency>

        <!-- Add logging framework, to produce console output when running in the IDE. -->
        <!-- These dependencies are excluded from the application JAR by default. -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.7</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>

            <!-- Java Compiler -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>

            <!-- We use the maven-shade plugin to create a fat jar that contains all necessary dependencies. -->
            <!-- Change the value of <mainClass>...</mainClass> if your program entry point changes. -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>3.0.0</version>
                <executions>
                    <!-- Run shade goal on package phase -->
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <artifactSet>
                                <excludes>
                                    <exclude>org.apache.flink:force-shading</exclude>
                                    <exclude>com.google.code.findbugs:jsr305</exclude>
                                    <exclude>org.slf4j:*</exclude>
                                    <exclude>log4j:*</exclude>
                                </excludes>
                            </artifactSet>
                            <filters>
                                <filter>
                                    <!-- Do not copy the signatures in the META-INF folder.
                                    Otherwise, this might cause SecurityExceptions when using the JAR. -->
                                    <artifact>*:*</artifact>
                                    <excludes>
                                        <exclude>META-INF/*.SF</exclude>
                                        <exclude>META-INF/*.DSA</exclude>
                                        <exclude>META-INF/*.RSA</exclude>
                                    </excludes>
                                </filter>
                            </filters>
                            <transformers>
                                <transformer
                                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>com.zm.StreamingJob</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>


    </build>

    <!-- This profile helps to make things run out of the box in IntelliJ -->
    <!-- Its adds Flink's core classes to the runtime class path. -->
    <!-- Otherwise they are missing in IntelliJ, because the dependency is 'provided' -->
    <profiles>
        <profile>
            <id>add-dependencies-for-IDEA</id>

            <activation>
                <property>
                    <name>idea.version</name>
                </property>
            </activation>

            <dependencies>
                <dependency>
                    <groupId>org.apache.flink</groupId>
                    <artifactId>flink-java</artifactId>
                    <version>${flink.version}</version>
                    <scope>compile</scope>
                </dependency>
                <dependency>
                    <groupId>org.apache.flink</groupId>
                    <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
                    <version>${flink.version}</version>
                    <scope>compile</scope>
                </dependency>
            </dependencies>
        </profile>
    </profiles>

</project>

2.准备资源文件

【kerberos认证相关】
krb5.conf
xxx.keytab

【Hive访问相关资源文件】
core-site.xml
hdfs-site.xml
hive-site.xml
mapred-site.xml
yarn-site.xml

 

三、示例代码

1、安全认证

// kerberos
        String confPath = "/conf/uat/krb5.conf";
        System.setProperty("java.security.krb5.conf", confPath);
        String keyPath = "/conf/uat/xx.keytab";
        UserGroupInformation.loginUserFromKeytab("xx@FAYSON.COM", keyPath);

2、初始化执行环境

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
env.setParallelism(1);

EnvironmentSettings envSettings = EnvironmentSettings.newInstance().useBlinkPlanner().inStreamingMode().build();
StreamTableEnvironment tableEnvironment = StreamTableEnvironment.create(env, envSettings);
tableEnvironment.getConfig().getConfiguration().set(ExecutionCheckpointingOptions.CHECKPOINTING_INTERVAL, Duration.ofSeconds(10));
tableEnvironment.getConfig().getConfiguration().set(ExecutionCheckpointingOptions.CHECKPOINTING_MODE, CheckpointingMode.EXACTLY_ONCE);

3、使用HiveCatalog构造TableEnvironment

String DEFAULT_CATALOG = "default_catalog";
String HIVE_CATALOG = "myhive";
String DEFAULT_DATABASE = "tmp";
String HIVE_CONF_DIR = "/path/resources";
Catalog catalog = new HiveCatalog(HIVE_CATALOG, DEFAULT_DATABASE, HIVE_CONF_DIR);
tableEnvironment.registerCatalog(HIVE_CATALOG, catalog);
tableEnvironment.useCatalog("myhive");

4、执行具体sql

// 构造kafka流表
TableResult tableResult = tableEnvironment.executeSql("DROP TABLE IF EXISTS ods_k_table_earliest");
tableResult.print();
TableResult tableResult2 = tableEnvironment.executeSql(
        "CREATE TABLE ods_k_table_earliest (\n" +
                "  user_id STRING,\n" +
                "  order_amount DOUBLE,\n" +
                "  log_ts TIMESTAMP(3),\n" +
                "  WATERMARK FOR log_ts AS log_ts - INTERVAL '5' SECOND\n" +
                " ) WITH (\n" +
                "     'connector.type' = 'kafka',\n" +
                "     'connector.version' = 'universal',\n " +
                "     'connector.topic' = 't_kafka_02',\n" +
                "     'connector.properties.bootstrap.servers' = 'xxx:9092',\n" +
                "     'connector.properties.zookeeper.connect' = 'xxx:2181',\n" +
                "     'connector.properties.group.id' = 'group_test_01',\n" +
                "     'connector.startup-mode' = 'earliest-offset',\n" +
                "     'format.type' = 'json'\n" +
                "   )");
tableResult2.print();

// 构造Hive目标表
TableResult t1 = tableEnvironment.executeSql("DROP TABLE IF EXISTS t_kafka_03");
t1.print();
TableResult tableResult3 = tableEnvironment.executeSql(
        "CREATE TABLE t_kafka_03 (\n" +
                " user_id STRING,\n" +
                " order_amount DOUBLE,\n" +
                " log_ts TIMESTAMP(3),\n" +
                " WATERMARK FOR log_ts AS log_ts - INTERVAL '5' SECOND\n" +
                ") WITH (\n" +
                "  'connector'='kafka',\n" +
                "  'topic'='t_kafka_03',\n" +
                "  'scan.startup.mode'='latest-offset',\n" +
                "  'properties.bootstrap.servers'='xxx:9092',\n" +
                "  'properties.group.id' = 'testGroup_01',\n" +
                "  'format'='json'\n" +
                ")");
tableResult3.print();


// 数据写入,无需提交,使用executeSql就能触发
tableEnvironment.getConfig().setSqlDialect(SqlDialect.HIVE);
TableResult tableResult4 = tableEnvironment.executeSql(
                "INSERT INTO  ods_hive_table " +
                        " SELECT user_id, order_amount, DATE_FORMAT(log_ts, 'yyyy-MM-dd'), DATE_FORMAT(log_ts, 'HH') FROM t_kafka_03");

5、Kafka客户端数据模拟写入

{"user_id":"a1111","order_amount":11.0,"log_ts":"2020-06-29 12:12:12"}
{"user_id":"a1111","order_amount":11.0,"log_ts":"2020-06-29 12:15:00"}
{"user_id":"a1111","order_amount":11.0,"log_ts":"2020-06-29 12:20:00"}
{"user_id":"a1111","order_amount":11.0,"log_ts":"2020-06-29 12:30:00"}
{"user_id":"a1111","order_amount":13.0,"log_ts":"2020-06-29 12:32:00"}
{"user_id":"a1112","order_amount":15.0,"log_ts":"2020-11-26 12:12:12"}
{"user_id":"a1112","order_amount":15.0,"log_ts":"2020-11-26 12:15:00"}
{"user_id":"a1112","order_amount":15.0,"log_ts":"2020-11-26 12:20:00"}
{"user_id":"a1112","order_amount":15.0,"log_ts":"2020-11-26 12:30:00"}
{"user_id":"a1112","order_amount":15.0,"log_ts":"2020-11-26 12:32:00"}

6、Hive输出

hive> select * from ods_hive_table;
OK
a1111 11.0  2020-06-29  12
a1111 11.0  2020-06-29  12
a1111 11.0  2020-06-29  12
a1111 11.0  2020-06-29  12
a1111 13.0  2020-06-29  12
a1112 15.0  2020-11-26  12
a1112 15.0  2020-11-26  12
a1112 15.0  2020-11-26  12
a1112 15.0  2020-11-26  12
a1112 15.0  2020-11-26  12
Time taken: 0.514 seconds, Fetched: 10 row(s)
hive> show partitions ods_hive_table;
OK
dt=2020-06-29/hr=12
dt=2020-11-26/hr=12
Time taken: 0.091 seconds, Fetched: 4 row(s)

 


总结

本次的测试数据旨在模拟FlinkSQL通过消费kafka写入Hive的完整流程,还未得到生产环境的验证,我这边测试的结果是消费延迟很低,或许和我测试规模有关,
我这里不清楚当大批量数据过来是不会有很明显的延迟,但是生产中如果能够接受一定的时间延迟,比如半小时,1个小时,作为近实时的数据分析是有FlinkSql还是可以支持的。
后面主要考虑模拟的场景更丰富些,添加一些监控措施,让实时的流程序更健壮。