Defining the Azure Databricks connection parameters for Spark Jobs

Complete the Databricks connection configuration in the Spark configuration tab of the Run view of your Job. This configuration is effective on a per-Job basis.

The information in this section is only for users who have subscribed to Talend Data Fabric or to any Talend product with Big Data but it is not applicable to Talend Open Studio for Big Data users.

Before you begin

When running a Spark Streaming Job, only one Job is allowed to run on the same Databricks cluster per time.
When running a Spark Batch Job, only if you have selected the Do not restart the cluster when submitting check box, you can send more than one Job to run in parallel on the same Databricks cluster; otherwise, since each run automatically restarts the cluster, the Jobs that are launched in parallel interrupt each other and thus cause execution failure.

Procedure

From the Cloud provider drop-down list, select Azure.

Enter the basic connection information to Databricks.

Standalone	In the Endpoint field, enter the URL address of your Azure Databricks workspace. This URL can be found in the Overview blade of your Databricks workspace page on your Azure portal. For example, this URL could look like https://westeurope.azuredatabricks.net. In the Cluster ID field, enter the ID of the Databricks cluster to be used. This ID is the value of the spark.databricks.clusterUsageTags.clusterId property of your Spark cluster. You can find this property on the properties list in the Environment tab in the Spark UI view of your cluster. You can also easily find this ID from the URL of your Databricks cluster. It is present immediately after cluster/ in this URL. Click the [...] button next to the Token field to enter the authentication token generated for your Databricks user account. You can generate or find this token on the User settings page of your Databricks workspace. For further information, see Token management from the Azure documentation. In the DBFS dependencies folder field, enter the directory that is used to store your Job related dependencies on Databricks Filesystem at runtime, putting a slash (/) at the end of this directory. For example, enter /jars/ to store the dependencies in a folder named jars. This folder is created on the fly if it does not exist then. Poll interval when retrieving Job status (in ms): enter, without the quotation marks, the time interval (in milliseconds) at the end of which you want the Studio to ask Spark for the status of your Job. For example, this status could be Pending or Running. The default value is `300000`, meaning 30 seconds. This interval is recommended by Databricks to correctly retrieve the Job status. Use transient cluster: you can select this check box to leverage the transient Databricks clusters. The custom properties you defined in the Advanced properties table are automatically taken into account by the transient clusters at runtime. Autoscale: select or clear this check box to define the number of workers to be used by your transient cluster. If you select this check box, autoscaling is enabled. Then define the minimum number of workers in Min workers and the maximum number of worders in Max workers. Your transient cluster is scaled up and down within this scope based on its workload. According to the Databricks documentation, autoscaling works best with Databricks runtime versions 3.0 or onwards. If you clear this check box, autoscaling is deactivated. Then define the number of workers a transient cluster is expected to have. This number does not include the Spark driver node. Node type and Driver node type: select the node types for the workers and the Spark driver node. These types determine the capacity of your nodes and their pricing by Databricks. For details about these node types and the Databricks Units they use, see Supported Instance Types from the Databricks documentation. Elastic disk: select this check box to enable your transient cluster to automatically scale up its disk space when its Spark workers are running low on disk space. For more details about this elastic disk feature, search for the section about autoscaling local storage from your Databricks documentation. SSH public key: if an SSH access has been set up for your cluster, enter the public key of the generated SSH key pair. This public key is automatically added to each node of your transient cluster. If no SSH access has been set up, ignore this field. For further information about SSH access to your cluster, see SSH access to clusters from the Databricks documentation. Configure cluster log: select this check box to define where to store your Spark logs for a long term. This storage system could be S3 or DBFS. Do not restart the cluster when submitting: select this check box to prevent the Studio restarting the cluster when the Studio is submitting your Jobs. However, if you make changes in your Jobs, clear this check box so that the Studio resarts your cluster to take these changes into account.

Standalone

In the Endpoint field, enter the URL address of your Azure Databricks workspace. This URL can be found in the Overview blade of your Databricks workspace page on your Azure portal. For example, this URL could look like https://westeurope.azuredatabricks.net.
In the Cluster ID field, enter the ID of the Databricks cluster to be used. This ID is the value of the spark.databricks.clusterUsageTags.clusterId property of your Spark cluster. You can find this property on the properties list in the Environment tab in the Spark UI view of your cluster.

You can also easily find this ID from the URL of your Databricks cluster. It is present immediately after cluster/ in this URL.
Click the [...] button next to the Token field to enter the authentication token generated for your Databricks user account. You can generate or find this token on the User settings page of your Databricks workspace. For further information, see Token management from the Azure documentation.
In the DBFS dependencies folder field, enter the directory that is used to store your Job related dependencies on Databricks Filesystem at runtime, putting a slash (/) at the end of this directory. For example, enter /jars/ to store the dependencies in a folder named jars. This folder is created on the fly if it does not exist then.
Poll interval when retrieving Job status (in ms): enter, without the quotation marks, the time interval (in milliseconds) at the end of which you want the Studio to ask Spark for the status of your Job. For example, this status could be Pending or Running.

The default value is 300000, meaning 30 seconds. This interval is recommended by Databricks to correctly retrieve the Job status.
Use transient cluster: you can select this check box to leverage the transient Databricks clusters.

The custom properties you defined in the Advanced properties table are automatically taken into account by the transient clusters at runtime.
1. Autoscale: select or clear this check box to define the number of workers to be used by your transient cluster.
  1. If you select this check box, autoscaling is enabled. Then define the minimum number of workers in Min workers and the maximum number of worders in Max workers. Your transient cluster is scaled up and down within this scope based on its workload.
    According to the Databricks documentation, autoscaling works best with Databricks runtime versions 3.0 or onwards.
  2. If you clear this check box, autoscaling is deactivated. Then define the number of workers a transient cluster is expected to have. This number does not include the Spark driver node.
2. Node type and Driver node type: select the node types for the workers and the Spark driver node. These types determine the capacity of your nodes and their pricing by Databricks.
  For details about these node types and the Databricks Units they use, see Supported Instance Types from the Databricks documentation.
3. Elastic disk: select this check box to enable your transient cluster to automatically scale up its disk space when its Spark workers are running low on disk space.
  For more details about this elastic disk feature, search for the section about autoscaling local storage from your Databricks documentation.
4. SSH public key: if an SSH access has been set up for your cluster, enter the public key of the generated SSH key pair. This public key is automatically added to each node of your transient cluster. If no SSH access has been set up, ignore this field.
  For further information about SSH access to your cluster, see SSH access to clusters from the Databricks documentation.
5. Configure cluster log: select this check box to define where to store your Spark logs for a long term. This storage system could be S3 or DBFS.
Do not restart the cluster when submitting: select this check box to prevent the Studio restarting the cluster when the Studio is submitting your Jobs. However, if you make changes in your Jobs, clear this check box so that the Studio resarts your cluster to take these changes into account.

Results

If you need the Job to be resilient to failure, select the Activate checkpointing check box to enable the Spark checkpointing operation. In the field that is displayed, enter the directory in which Spark stores, in the file system of the cluster, the context data of the computations such as the metadata and the generated RDDs of this computation.

For further information about the Spark checkpointing operation, see http://spark.apache.org/docs/latest/streaming-programming-guide.html#checkpointing .

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