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Understanding Spark Configurations with Apache Iceberg

November 22, 2022

Apache Iceberg

Apache Iceberg is quickly becoming the industry standard for interfacing with data on data lakes. A lot of the time when people first try out Iceberg they do so using Apache Spark.

Often to start spark up you may run a command like this: 

spark-sql --packages org.apache.iceberg:iceberg-spark-runtime-3.2_2.12:1.0.0\
    --conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions \
    --conf spark.sql.catalog.spark_catalog=org.apache.iceberg.spark.SparkSessionCatalog \
    --conf spark.sql.catalog.spark_catalog.type=hive \
    --conf spark.sql.catalog.local=org.apache.iceberg.spark.SparkCatalog \
    --conf spark.sql.catalog.local.type=hadoop \
    --conf spark.sql.catalog.local.warehouse=$PWD/warehouse

The goal of this article is help demystify this so you can configure Spark for Iceberg in any context.

Spark Configurations

Spark configs can be defined in a few ways:

  • As flags when starting Spark
  • Using Imperitive function calls

Flags

There are are several flags you can pass to the spark-shell or spark-sql commands.

  • --package will identify maven packages you want installed and useable during the Spark session
--packages org.projectnessie:nessie-spark-3.2-extensions:0.43.0,org.apache.iceberg:iceberg-spark-runtime-3.2_2.12:0.14.0,software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178
  • --jar will allow you to pass paths to existing 
--jars /home/docker/iceberg-spark-runtime-3.2_2.12-1.0.0.jar,/home/docker/nessie-spark-extensions-3.2_2.12-0.44.0.jar
  • --conf will allow you configure many properties of your spark session in a “key”=“value” format.
    --conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions \
    --conf spark.sql.catalog.spark_catalog=org.apache.iceberg.spark.SparkSessionCatalog \

Function Calls

Similarly, you can configure your Spark Session directly from your Scala or Python Spark scripts:

SCALA

val conf: SparkConf = new SparkConf()
  conf.setAppName("yo")
  conf.set("spark.jars.packages", "org.projectnessie:nessie-spark-3.2-extensions:0.43.0,org.apache.iceberg:iceberg-spark-runtime-3.2_2.12:0.14.0,software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178")
  conf.set(spark.sql.catalog.spark_catalog","org.apache.iceberg.spark.SparkSessionCatalog")

PYTHON

conf = SparkConf()

conf.set(
    "spark.jars.packages",
    "org.projectnessie:nessie-spark-3.2-extensions:0.43.0,org.apache.iceberg:iceberg-spark-runtime-3.2_2.12:0.14.0,software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178",
)

conf.set("spark.sql.catalog.spark_catalog", "org.apache.iceberg.spark.SparkSessionCatalog")

Packages

Here is a list of the some of the packages you may want to include with your --packages flag and why.

Library Purpose
org.apache.iceberg:iceberg-spark-runtime-3.3_2.12:1.0.0 The main iceberg library, make sure to use the right one for the version of spark and iceberg you are using
org.projectnessie:nessie-spark-extensions-3.3_2.12:0.44.0 Library for working with Nessie based catalogs like Dremio Arctic
software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178 Libraries for working with AWS S3

Configurations

Configuration Purpose Possible Values
spark.sql.extensions Configure any extensions of SQL support in Spark. Each extension can be seperated with a comma “org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,org.projectnessie.spark.extensions.NessieSparkSessionExtensions”
spark.sql.catalog.CatalogName This configures a new catalog under whatever name you want (just change CatalogName to desired name) to a particular implementation of SparkCatalog org.apache.iceberg.spark.SparkCatalog
spark.sql.catalog.CatalogName.io-impl This changes IO implementations of the target catalog, mainly changed for writing to Object Storage org.apache.iceberg.aws.s3.S3FileIO
spark.sql.catalog.CatalogName.warehouse Determines where new tables will be written to for that particular catalog A file or S3 path
spark.sql.catalog.CatalogName.catalog-impl The particular type of catalog your using Nessie - org.apache.iceberg.nessie.NessieCatalog, Hive - NA, JDBC - org.apache.iceberg.jdbc.JdbcCatalog, AWS Glue - org.apache.iceberg.aws.glue.GlueCatalog

|

Amazon S3 Credentials

--conf spark.hadoop.fs.s3a.access.key=$AWS_ACCESS_KEY \
--conf spark.hadoop.fs.s3a.secret.key=$AWS_SECRET_ACCESS_KEY

Environmental Variables

In a lot of the upcoming snippets I’ll be using different environmental variables. If you want to use the snippets as is, then define the follow environmental variables:

export TOKEN=XXXXXX
export WAREHOUSE=s3a://.../
export AWS_ACCESS_KEY_ID=XXXXXX
export AWS_SECRET_ACCESS_KEY=XXXXXX
export URI=https://...
export AWS_REGION=us-east-1
export DB_USERNAME=xxxxxx
export DB_PASSWORD=xxxxx
  • TOKEN: auth token for Nessie catalogs
  • WAREHOUSE: Where tables will be written
  • AWS_XXXX= AWS Credentials
  • URI= The Hive, Nessie or JDBC URI
  • DBUSERNAME and DBPASSWORD are for using a JDBC database like mySQL or Postgres

Sample Configurations

Below you’ll find sample configurations for many catalog types for reference.

If you want to try some of these in a locally running Docker container with Spark, use this command to spin one up.

docker run -it -p 8080:8080 --name spark-playground alexmerced/spark33playground

NOTE: port 8080 is exposed in case you want run a Jupyter Notebook server in the container

HIVE

spark-sql --packages org.apache.iceberg:iceberg-spark-runtime-3.3_2.12:1.0.0\
    --conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions \
    --conf spark.sql.catalog.spark_catalog=org.apache.iceberg.spark.SparkSessionCatalog \
    --conf spark.sql.catalog.spark_catalog.type=hive \
    --conf spark.sql.catalog.hive=org.apache.iceberg.spark.SparkCatalog \
    --conf spark.sql.catalog.hive.type=hadoop \
    --conf spark.sql.catalog.hive.uri=$URI \
    --conf spark.sql.catalog.hive.warehouse=$WAREHOUSE

AWS GLUE

spark-sql --packages "org.apache.iceberg:iceberg-spark-runtime-3.3_2.12:1.0.0,software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178" \
    --conf spark.sql.catalog.glue=org.apache.iceberg.spark.SparkCatalog \
    --conf spark.sql.catalog.glue.warehouse=$WAREHOUSE \
    --conf spark.sql.catalog.glue.catalog-impl=org.apache.iceberg.aws.glue.GlueCatalog \
    --conf spark.sql.catalog.glue.io-impl=org.apache.iceberg.aws.s3.S3FileIO \
    --conf spark.hadoop.fs.s3a.access.key=$AWS_ACCESS_KEY \
    --conf spark.hadoop.fs.s3a.secret.key=$AWS_SECRET_ACCESS_KEY

NESSIE/DREMIO ARCTIC

Nessie catalogs provide you git-like semantics with your Iceberg catalogs (Merging, Branching, Rollbacks) and if you want to get hands on to see how this works try this Dremio Arctic tutorial.

spark-sql --packages "org.apache.iceberg:iceberg-spark-runtime-3.3_2.12:1.0.0,org.projectnessie:nessie-spark-extensions-3.3_2.12:0.44.0,software.amazon.awssdk:bundle:2.17.178,software.amazon.awssdk:url-connection-client:2.17.178" \
--conf spark.sql.extensions="org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,org.projectnessie.spark.extensions.NessieSparkSessionExtensions" \
--conf spark.sql.catalog.nessie.uri=$ARCTIC_URI \
--conf spark.sql.catalog.nessie.ref=main \
--conf spark.sql.catalog.nessie.authentication.type=BEARER \
--conf spark.sql.catalog.nessie.authentication.token=$TOKEN \
--conf spark.sql.catalog.nessie.catalog-impl=org.apache.iceberg.nessie.NessieCatalog \
--conf spark.sql.catalog.nessie.warehouse=$WAREHOUSE \
--conf spark.sql.catalog.nessie=org.apache.iceberg.spark.SparkCatalog \
--conf spark.sql.catalog.nessie.io-impl=org.apache.iceberg.aws.s3.S3FileIO

JDBC

This allows you to use Postgres, MySQL or any JDBC compatible database as a catalog.

Make sure to pass the right username and password for your database.

spark-sql --packages org.apache.iceberg:iceberg-spark-runtime-3.2_2.12:1.0.0 \
    --conf spark.sql.catalog.my_catalog=org.apache.iceberg.spark.SparkCatalog \
    --conf spark.sql.catalog.jdbc.warehouse=$WAREHOUSE \
    --conf spark.sql.catalog.jdbc.catalog-impl=org.apache.iceberg.jdbc.JdbcCatalog \
    --conf spark.sql.catalog.jdbc.uri=$URI \
    --conf spark.sql.catalog.jdbc.jdbc.verifyServerCertificate=true \
    --conf spark.sql.catalog.jdbc.jdbc.useSSL=true \
    --conf spark.sql.catalog.jdbc.jdbc.user=$DB_USERNAME \
    --conf spark.sql.catalog.jdbc.jdbc.password=$DB_PASSWORD

Conclusion

Once you’ve configured your Spark session keep in mind you must use the configured namespace for all queries. For example if I configured the catalog with:

    --conf spark.sql.catalog.mycoolcatalog.catalog-impl=org.apache.iceberg.jdbc.JdbcCatalog \

Then creating a table would look like:

CREATE TABLE mycoolcatalog.table1 (name STRING) USING iceberg;

Aside from that consult the Iceberg Documentation or this Apache Iceberg 101 article for more information.

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