How do I configure Spark properties to use a service principal for accessing Azure Data Lake Storage Gen2 or Blob Storage in Databricks?
To configure Spark properties to use a service principal for accessing Azure Data Lake Storage Gen2 or Blob Storage in Databricks, you can follow these steps:

1. Set the following Spark properties in a cluster’s Spark configuration or a notebook:
```python
spark.hadoop.fs.azure.account.auth.type.<storage-account>.dfs.core.windows.net OAuth
spark.hadoop.fs.azure.account.oauth.provider.type.<storage-account>.dfs.core.windows.net org.apache.hadoop.fs.azurebfs.oauth2.ClientCredsTokenProvider
spark.hadoop.fs.azure.account.oauth2.client.id.<storage-account>.dfs.core.windows.net <application-id>
spark.hadoop.fs.azure.account.oauth2.client.secret.<storage-account>.dfs.core.windows.net {{secrets/<secret-scope>/<service-credential-key>}}
spark.hadoop.fs.azure.account.oauth2.client.endpoint.<storage-account>.dfs.core.windows.net https://login.microsoftonline.com/<directory-id>/oauth2/token
```
2. Replace the placeholders with the appropriate values:
* `<storage-account>`: The name of the Azure storage account.
* `<application-id>`: The Application (client) ID for the Microsoft Entra ID application.
* `<directory-id>`: The Directory (tenant) ID for the Microsoft Entra ID application.
* `<secret-scope>`: The Databricks secret scope name.
* `<service-credential-key>`: The name of the key containing the client secret.

Here's an example of how to set the Spark properties in a notebook:
```python
service_credential = dbutils.secrets.get(scope="<secret-scope>",key="<service-credential-key>")
spark.conf.set("fs.azure.account.auth.type.<storage-account>.dfs.core.windows.net", "OAuth")
spark.conf.set("fs.azure.account.oauth.provider.type.<storage-account>.dfs.core.windows.net", "org.apache.hadoop.fs.azurebfs.oauth2.ClientCredsTokenProvider")
spark.conf.set("fs.azure.account.oauth2.client.id.<storage-account>.dfs.core.windows.net", "<application-id>")
spark.conf.set("fs.azure.account.oauth2.client.secret.<storage-account>.dfs.core.windows.net", service_credential)
spark.conf.set("fs.azure.account.oauth2.client.endpoint.<storage-account>.dfs.core.windows.net", "https://login.microsoftonline.com/<directory-id>/oauth2/token")
```
By setting these Spark properties, you can use a service principal to access Azure Data Lake Storage Gen2 or Blob Storage in Databricks.