Apache Flink – External Jar

i’m trying to create a Flink application using maven and an extra dependency :

 <dependency>
      <groupId>com.microsoft.sqlserver</groupId>
      <artifactId>mssql-jdbc</artifactId>
      <version>8.2.2.jre11</version>
  </dependency>

Im trying to fetch extra information from our database. When I run the code locally, everything is fine, but when run on Flink, I get this error message :

So my initial tought was the dependency was not loaded on the fat jar using the maven shadow pluging, but I think it is.

My Flink is run in a docker container, Ive open port 1433:1433 on the container (in the compose).

My goal is to add SQL data to the stream for an alerting system with custom rules by user.

Here is the content of my pom.xml :

–> http://maven.apache.org/xsd/maven-4.0.0.xsd”> 4.0.0

<groupId>org.qscale</groupId>
<artifactId>FlinkPrototype</artifactId>
<version>1.0</version>
<packaging>jar</packaging>

<name>Flink Quickstart Job</name>
<url>http://www.myorganization.org</url>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <flink.version>1.10.0</flink.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>

<repositories>
    <repository>
        <id>apache.snapshots</id>
        <name>Apache Development Snapshot Repository</name>
        <url>https://repository.apache.org/content/repositories/snapshots/</url>
        <releases>
            <enabled>false</enabled>
        </releases>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
</repositories>

<dependencies>
    <!-- Apache Flink dependencies -->
    <!-- These dependencies are provided, because they should not be packaged into the JAR file. -->
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-java</artifactId>
        <version>${flink.version}</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
        <version>${flink.version}</version>
        <scope>provided</scope>
    </dependency>

    <!-- Add connector dependencies here. They must be in the default scope (compile). -->

    <!-- Example:

    <dependency>
        <groupId>org.apache.flink</groupId>
        <artifactId>flink-connector-kafka-0.10_${scala.binary.version}</artifactId>
        <version>${flink.version}</version>
    </dependency>
    -->

    <!-- Project dependencies -->
    <dependency>
        <groupId>com.microsoft.sqlserver</groupId>
        <artifactId>mssql-jdbc</artifactId>
        <version>8.2.2.jre11</version>
    </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>runtime</scope>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
        <scope>runtime</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>3.1.1</version>
            <executions>
                <!-- Run shade goal on package phase -->
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <shadedArtifactAttached>true</shadedArtifactAttached>
                        <shadedClassifierName>shaded</shadedClassifierName>
                        <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>org.qscale.StreamingJob</mainClass>
                            </transformer>
                        </transformers>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>

    <pluginManagement>
        <plugins>

            <!-- This improves the out-of-the-box experience in Eclipse by resolving some warnings. -->
            <plugin>
                <groupId>org.eclipse.m2e</groupId>
                <artifactId>lifecycle-mapping</artifactId>
                <version>1.0.0</version>
                <configuration>
                    <lifecycleMappingMetadata>
                        <pluginExecutions>
                            <pluginExecution>
                                <pluginExecutionFilter>
                                    <groupId>org.apache.maven.plugins</groupId>
                                    <artifactId>maven-shade-plugin</artifactId>
                                    <versionRange>[3.1.1,)</versionRange>
                                    <goals>
                                        <goal>shade</goal>
                                    </goals>
                                </pluginExecutionFilter>
                                <action>
                                    <ignore/>
                                </action>
                            </pluginExecution>
                            <pluginExecution>
                                <pluginExecutionFilter>
                                    <groupId>org.apache.maven.plugins</groupId>
                                    <artifactId>maven-compiler-plugin</artifactId>
                                    <versionRange>[3.1,)</versionRange>
                                    <goals>
                                        <goal>testCompile</goal>
                                        <goal>compile</goal>
                                    </goals>
                                </pluginExecutionFilter>
                                <action>
                                    <ignore/>
                                </action>
                            </pluginExecution>
                        </pluginExecutions>
                    </lifecycleMappingMetadata>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>
</build>

Thank you for your help !

Answer

Adding Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver") in your main method will work for you I think because shading seems correct.

The other problem is that you are using java 1.8 to compile in your pom but you are adding a dependency compiled with java 11. Changing the jdbc version to the following will hopefully work.

<dependency>
      <groupId>com.microsoft.sqlserver</groupId>
      <artifactId>mssql-jdbc</artifactId>
      <version>8.2.2.jre8</version>
  </dependency>

Please read this for more details