How Do You Pass the -d Parameter or Environment Variable to a Spark Job?

Passing environment variables or parameters to a Spark job can be done in various ways. Here, we will discuss two common approaches: using configuration settings via the `–conf` or `–files` options and using the `spark-submit` command-line tool with custom parameters.

Using Configuration Settings

You can pass environment variables directly to Spark jobs using the `–conf` option with `spark-submit`. Here is an example:

PySpark Example

Let’s assume you want to pass an environment variable `MY_ENV_VAR` to the Spark job. You can set this variable in your Python code as:

import os
from pyspark.sql import SparkSession

# Create Spark session
spark = SparkSession.builder.appName("EnvironmentVariableExample").getOrCreate()

# Access the environment variable
my_env_var = os.environ.get("MY_ENV_VAR")
print(f"MY_ENV_VAR: {my_env_var}")

# Stop the spark session
spark.stop()

Then, you can pass the environment variable while submitting the job:

export MY_ENV_VAR="my_value"
spark-submit --conf spark.yarn.appMasterEnv.MY_ENV_VAR=$MY_ENV_VAR my_script.py

Scala Example

Here’s how you can handle the environment variable in a Scala Spark application:

import org.apache.spark.sql.SparkSession

object EnvironmentVariableExample {
  def main(args: Array[String]): Unit = {
    val spark = SparkSession.builder.appName("EnvironmentVariableExample").getOrCreate()

    // Access the environment variable
    val myEnvVar = sys.env.get("MY_ENV_VAR").getOrElse("")
    println(s"MY_ENV_VAR: $myEnvVar")

    // Stop the spark session
    spark.stop()
  }
}

Submit the Scala job similarly:

export MY_ENV_VAR="my_value"
spark-submit --conf spark.yarn.appMasterEnv.MY_ENV_VAR=$MY_ENV_VAR my_script.jar

Using Spark Configuration Settings

Another approach involves customizing Spark configurations programmatically within the code, without the need for environment variables. Here is an example:

Scala Example with Custom Parameters

Define the custom parameter in your code and pass it via the `spark-submit` command:

import org.apache.spark.sql.SparkSession

object CustomParameterExample {
  def main(args: Array[String]): Unit = {
    val spark = SparkSession.builder.appName("CustomParameterExample").getOrCreate()

    // Access custom parameter
    val customParam = spark.conf.get("spark.custom.param", "default_value")
    println(s"Custom Parameter: $customParam")

    // Stop the spark session
    spark.stop()
  }
}

Submit the job with the custom parameter:

spark-submit --conf spark.custom.param="my_custom_value" my_script.jar

PySpark Example with Custom Parameters

You can achieve similar results using PySpark:

from pyspark.sql import SparkSession

# Create Spark session
spark = SparkSession.builder.appName("CustomParameterExample").getOrCreate()

# Access the custom parameter
custom_param = spark.conf.get("spark.custom.param", "default_value")
print(f"Custom Parameter: {custom_param}")

# Stop the Spark session
spark.stop()

Submit the PySpark job with the custom parameter:

spark-submit --conf spark.custom.param="my_custom_value" my_script.py

Summary

To summarize, you can pass environment variables or custom parameters to a Spark job via the `–conf` option in the `spark-submit` command. You can then access these variables or parameters from your Spark application using appropriate methods in the language you are using, such as `os.environ` in Python or `sys.env` in Scala.

About Editorial Team

Our Editorial Team is made up of tech enthusiasts deeply skilled in Apache Spark, PySpark, and Machine Learning, alongside proficiency in Pandas, R, Hive, PostgreSQL, Snowflake, and Databricks. They're not just experts; they're passionate educators, dedicated to demystifying complex data concepts through engaging and easy-to-understand tutorials.