Add polaris spark client webpage under unreleased

plugins/spark/README.md

@@ -30,6 +30,12 @@ and depends on iceberg-spark-runtime 1.8.1.
 
 # Build Plugin Jar
 A task createPolarisSparkJar is added to build a jar for the Polaris Spark plugin, the jar is named as:
+`polaris-iceberg-<icebergVersion>-spark-runtime-<sparkVersion>_<scalaVersion>-<polarisVersion>.jar`. For example:
+`polaris-iceberg-1.8.1-spark-runtime-3.5_2.12-0.10.0-beta-incubating-SNAPSHOT.jar`.
+
+- `./gradlew :polaris-spark-3.5_2.12:createPolarisSparkJar` -- build jar for Spark 3.5 with Scala version 2.12.
+- `./gradlew :polaris-spark-3.5_2.13:createPolarisSparkJar` -- build jar for Spark 3.5 with Scala version 2.13.
+
 The result jar is located at plugins/spark/v3.5/build/<scala_version>/libs after the build.
 
 # Start Spark with Local Polaris Service using built Jar
@@ -51,13 +57,12 @@ bin/spark-shell \
 --conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,io.delta.sql.DeltaSparkSessionExtension \
 --conf spark.sql.catalog.spark_catalog=org.apache.spark.sql.delta.catalog.DeltaCatalog \
 --conf spark.sql.catalog.<catalog-name>.warehouse=<catalog-name> \
---conf spark.sql.catalog.<catalog-name>.header.X-Iceberg-Access-Delegation=true \
+--conf spark.sql.catalog.<catalog-name>.header.X-Iceberg-Access-Delegation=vended-credentials \
 --conf spark.sql.catalog.<catalog-name>=org.apache.polaris.spark.SparkCatalog \
 --conf spark.sql.catalog.<catalog-name>.uri=http://localhost:8181/api/catalog \
 --conf spark.sql.catalog.<catalog-name>.credential="root:secret" \
 --conf spark.sql.catalog.<catalog-name>.scope='PRINCIPAL_ROLE:ALL' \
 --conf spark.sql.catalog.<catalog-name>.token-refresh-enabled=true \
---conf spark.sql.catalog.<catalog-name>.type=rest \
 --conf spark.sql.sources.useV1SourceList=''
 ```
 
@@ -72,24 +77,24 @@ bin/spark-shell \
 --conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,io.delta.sql.DeltaSparkSessionExtension \
 --conf spark.sql.catalog.spark_catalog=org.apache.spark.sql.delta.catalog.DeltaCatalog \
 --conf spark.sql.catalog.polaris.warehouse=<catalog-name> \
---conf spark.sql.catalog.polaris.header.X-Iceberg-Access-Delegation=true \
+--conf spark.sql.catalog.polaris.header.X-Iceberg-Access-Delegation=vended-credentials \
 --conf spark.sql.catalog.polaris=org.apache.polaris.spark.SparkCatalog \
 --conf spark.sql.catalog.polaris.uri=http://localhost:8181/api/catalog \
 --conf spark.sql.catalog.polaris.credential="root:secret" \
 --conf spark.sql.catalog.polaris.scope='PRINCIPAL_ROLE:ALL' \
 --conf spark.sql.catalog.polaris.token-refresh-enabled=true \
---conf spark.sql.catalog.polaris.type=rest \
 --conf spark.sql.sources.useV1SourceList=''
 ```
 
 # Limitations
 The Polaris Spark client supports catalog management for both Iceberg and Delta tables, it routes all Iceberg table 
 requests to the Iceberg REST endpoints, and routes all Delta table requests to the Generic Table REST endpoints.
 
-Following describes the current limitations of the Polaris Spark client:
+The Spark Client requires at least delta 3.2.1 to work with Delta tables, which requires at least Apache Spark 3.5.3.
+Following describes the current functionality limitations of the Polaris Spark client:
 1) Create table as select (CTAS) is not supported for Delta tables. As a result, the `saveAsTable` method of `Dataframe`
    is also not supported, since it relies on the CTAS support.
 2) Create a Delta table without explicit location is not supported.
 3) Rename a Delta table is not supported.
 4) ALTER TABLE ... SET LOCATION/SET FILEFORMAT/ADD PARTITION is not supported for DELTA table.
-5) For other non-iceberg tables like csv, there is no specific guarantee provided today.
+5) For other non-Iceberg tables like csv, it is not supported today.

site/content/in-dev/unreleased/polaris-spark-client.md

@@ -0,0 +1,130 @@
+---
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+Title: Polaris Spark Client
+type: docs
+weight: 650
+---
+
+Apache Polaris now provides Catalog support for Generic Tables (non-Iceberg tables), please check out 
+the [Catalog API Spec]({{% ref "polaris-catalog-service" %}}) for Generic Table API specs.
+
+Along with the Generic Table Catalog support, Polaris is also releasing a Spark client, which helps to 
+provide an end-to-end solution for Apache Spark to manage Delta tables using Polaris.
+
+Note the Polaris Spark client is able to handle both Iceberg and Delta tables, not just Delta.
+
+This page documents how to connect Spark with Polaris Service using the Polaris Spark client.
+
+## Quick Start with Local Polaris service
+If you want to quickly try out the functionality with a local Polaris service, simply check out the Polaris repo 
+and follow the instructions in the Spark plugin getting-started 
+[README](https://github.com/apache/polaris/blob/main/plugins/spark/v3.5/getting-started/README.md).
+
+Check out the Polaris repo:
+```shell
+cd ~
+git clone https://github.com/apache/polaris.git
+```
+
+## Start Spark against a deployed Polaris service
+Before starting, ensure that the deployed Polaris service supports Generic Tables, and that Spark 3.5(version 3.5.3 or later is installed).
+Spark 3.5.5 is recommended, and you can follow the instructions below to get a Spark 3.5.5 distribution.
+```shell
+cd ~
+wget https://archive.apache.org/dist/spark/spark-3.5.5/spark-3.5.5-bin-hadoop3.tgz 
+mkdir spark-3.5
+tar xzvf spark-3.5.5-bin-hadoop3.tgz  -C spark-3.5 --strip-components=1
+cd spark-3.5
+```
+
+### Connecting with Spark using the Polaris Spark client
+The following CLI command can be used to start the Spark with connection to the deployed Polaris service using
+a released Polaris Spark client.
+
+```shell
+bin/spark-shell \
+--packages <polaris-spark-client-package>,org.apache.hadoop:hadoop-aws:3.4.0,io.delta:delta-spark_2.12:3.3.1 \
+--conf spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,io.delta.sql.DeltaSparkSessionExtension \
+--conf spark.sql.catalog.spark_catalog=org.apache.spark.sql.delta.catalog.DeltaCatalog \
+--conf spark.sql.catalog.<spark-catalog-name>.warehouse=<polaris-catalog-name> \
+--conf spark.sql.catalog.<spark-catalog-name>.header.X-Iceberg-Access-Delegation=vended-credentials \
+--conf spark.sql.catalog.<spark-catalog-name>=org.apache.polaris.spark.SparkCatalog \
+--conf spark.sql.catalog.<spark-catalog-name>.uri=<polaris-service-uri> \
+--conf spark.sql.catalog.<spark-catalog-name>.credential='<client-id>:<client-secret>' \
+--conf spark.sql.catalog.<spark-catalog-name>.scope='PRINCIPAL_ROLE:ALL' \
+--conf spark.sql.catalog.<spark-catalog-name>.token-refresh-enabled=true
+```
+Assume the released Polaris Spark client you want to use is `org.apache.polaris:polaris-iceberg-1.8.1-spark-runtime-3.5_2.12:1.0.0`,
+replace the `polaris-spark-client-package` field with the release.
+
+The `spark-catalog-name` is the catalog name you will use with Spark, and `polaris-catalog-name` is the catalog name used 
+by Polaris service, for simplicity, you can use the same name. 
+
+Replace the `polaris-service-uri` with the uri of the deployed Polaris service. For example, with a locally deployed
+Polaris service, the uri would be `http://localhost:8181/api/catalog`.
+
+For `client-id` and `client-secret` values, you can refer to [Using Polaris]({{% ref "getting-started/using-polaris" %}}) 
+for more details.
+
+You can also start the connection by programmatically initialize a SparkSession, following is an example with PySpark:
+```python
+from pyspark.sql import SparkSession
+
+spark = SparkSession.builder
+  .config("spark.jars.packages", "<polaris-spark-client-package>,org.apache.hadoop:hadoop-aws:3.3.4,io.delta:delta-spark_2.12:3.3.1")
+  .config("spark.sql.catalog.spark_catalog", "org.apache.spark.sql.delta.catalog.DeltaCatalog")
+  .config("spark.sql.extensions", "org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions,io.delta.sql.DeltaSparkSessionExtension")
+  .config("spark.sql.catalog.<spark-catalog-name>", "org.apache.polaris.spark.SparkCatalog")  
+  .config("spark.sql.catalog.<spark-catalog-name>.uri", <polaris-service-uri>)
+  .config("spark.sql.catalog.<spark-catalog-name>.token-refresh-enabled", "true")
+  .config("spark.sql.catalog.<spark-catalog-name>.credential", "<client-id>:<client_secret>")
+  .config("spark.sql.catalog.<spark-catalog-name>.warehouse", <polaris_catalog_name>)
+  .config("spark.sql.catalog.polaris.scope", 'PRINCIPAL_ROLE:ALL')
+  .config("spark.sql.catalog.polaris.header.X-Iceberg-Access-Delegation", 'vended-credentials')
+  .getOrCreate()
+```
+Similar as the CLI command, make sure the corresponding fields are replaced correctly.
+
+### Create tables with Spark
+After Spark is started, you can use it to create and access Iceberg and Delta tables, for example:
+```python
+spark.sql("USE polaris")
+spark.sql("CREATE NAMESPACE IF NOT EXISTS DELTA_NS")
+spark.sql("CREATE NAMESPACE IF NOT EXISTS DELTA_NS.PUBLIC")
+spark.sql("USE NAMESPACE DELTA_NS.PUBLIC")
+spark.sql("""CREATE TABLE IF NOT EXISTS PEOPLE (
+    id int, name string)
+USING delta LOCATION 'file:///tmp/var/delta_tables/people';
+""")
+```
+
+## Connecting with Spark using local Polaris Spark client jar
+If you would like to use a version of the Spark client that is currently not yet released, you can
+build a Spark client jar locally from source. Please check out the Polaris repo and refer to the Spark plugin
+[README](https://github.com/apache/polaris/blob/main/plugins/spark/README.md) for detailed instructions.
+
+## Limitations
+The Polaris Spark client has the following functionality limitations:
+1) Create table as select (CTAS) is not supported for Delta tables. As a result, the `saveAsTable` method of `Dataframe`
+   is also not supported, since it relies on the CTAS support.
+2) Create a Delta table without explicit location is not supported.
+3) Rename a Delta table is not supported.
+4) ALTER TABLE ... SET LOCATION/SET FILEFORMAT/ADD PARTITION is not supported for DELTA table.
+5) For other non-Iceberg tables like csv, it is not supported.