How to access secrets in databricks initscript

Another answer is correct regarding the syntax of the secrets reference (so-called "secret paths"), but it won't work for init scripts, although it will work for Spark code itself.

To pass the secret to the init script you need to put the secrets path into the "Environment Variables" sections of the Spark configuration tab, like this:

And after that you can use the variable by name inside the init script:

if [ -n "$SECRET_VAR" ]; then
  do_something_with_it
fi

Here are the steps to access secrets in databricks initscript:

1. Go to cluster
2. Click Edit next to the Cluster information.
3. On the Configure Cluster page, click Advanced Options.
4. On the Spark tab, enter the following Spark Config:

Sample ini code:

 fs.azure.account.auth.type.chepragen2.dfs.core.windows.net OAuth
 fs.azure.account.oauth.provider.type.chepragen2.dfs.core.windows.net org.apache.hadoop.fs.azurebfs.oauth2.ClientCredsTokenProvider
 fs.azure.account.oauth2.client.id.chepragen2.dfs.core.windows.net {<!-- -->{secrets/KeyVaultName/ClientID}}
 fs.azure.account.oauth2.client.secret.chepragen2.dfs.core.windows.net {<!-- -->{secrets/KeyVaultName/ClientSecret}}
 fs.azure.account.oauth2.client.endpoint.chepragen2.dfs.core.windows.net https://login.microsoftonline.com/<Directory_ID>/oauth2/token

For more details, refer Azure Databricks - configure the cluster to read secrets from the secret scope.