Utilize the power of Spark to interact with the metadata on lakeFS. Possible use-cases include:

• Create a DataFrame for listing the objects in a specific commit or branch.
• Compute changes between two commits.
• Export your data for consumption outside lakeFS.
• Bulk operations on underlying storage.

Start Spark Shell / PySpark with the --packages flag:

spark-shell --packages io.treeverse:lakefs-spark-client_2.12:0.1.0-SNAPSHOT

1. To read metadata from lakeFS, the client should be configured with your lakeFS endpoint and credentials, using the following Hadoop configurations:

   Configuration	Description
   spark.hadoop.lakefs.api.url	lakeFS API endpoint, e.g: http://lakefs.example.com/api/v1
   spark.hadoop.lakefs.api.access_key	The access key to use for fetching metadata from lakeFS
   spark.hadoop.lakefs.api.secret_key	Corresponding lakeFS secret key

2. The client will also directly interact with your storage using Hadoop FileSystem. Therefore, your Spark session must be able to access the underlying storage of your lakeFS repository. For instance, running as a user with a personal account on S3 (not in production) you might add:

   Configuration	Description
   spark.hadoop.fs.s3a.access.key	Access key to use for accessing underlying storage on S3
   spark.hadoop.fs.s3a.secret.key	Corresponding secret key to use with S3 access key

1. Get a DataFrame for listing all objects in a commit:

   import io.treeverse.clients.LakeFSContext
   
   val commitID = "a1b2c3d4"
   val df = LakeFSContext.newDF(spark, "example-repo", commitID)
   df.show
   /* output example:
      +------------+--------------------+--------------------+-------------------+----+
      |        key |             address|                etag|      last_modified|size|
      +------------+--------------------+--------------------+-------------------+----+
      |     file_1 |791457df80a0465a8...|7b90878a7c9be5a27...|2021-03-05 11:23:30|  36|
      |     file_2 |e15be8f6e2a74c329...|95bee987e9504e2c3...|2021-03-05 11:45:25|  36|
      |     file_3 |f6089c25029240578...|32e2f296cb3867d57...|2021-03-07 13:43:19|  36|
      |     file_4 |bef38ef97883445c8...|e920efe2bc220ffbb...|2021-03-07 13:43:11|  13|
      +------------+--------------------+--------------------+-------------------+----+
    */

2. Run SQL queries on your metadata:

    df.createOrReplaceTempView("files")
    spark.sql("SELECT DATE(last_modified), COUNT(*) FROM files GROUP BY 1 ORDER BY 1")
    /* output example:
       +----------+--------+
       |        dt|count(1)|
       +----------+--------+
       |2021-03-05|       2|
       |2021-03-07|       2|
       +----------+--------+
     */