Access a database with fine-grained access control

This page explains how to access a Spanner database when you are a fine-grained access control user.

To learn about fine-grained access control, see About fine-grained access control.

As a fine-grained access control user, you must select a database role to use to execute SQL statements and queries, and to perform row operations on a database. Your role selection persists throughout your session until you change the role.

When you submit a query, DML, or row operation, Spanner checks authorization by using the following rules:

Google Cloud console

Spanner first checks if you have database-level IAM permissions. If so, the Google Cloud console doesn't show a database role selector, and your session proceeds with your database-level permissions.

• If you have only fine-grained access control privileges and no IAM database-level permissions, you must have been granted access to the spanner_sys_reader system role or one of its member roles. Select a role on the database Overview page so that your Google Cloud console session proceeds with the required privileges.

  Note: To interact with Spanner resources in the Google Cloud console, you must have the roles/spanner.viewer IAM role.

Google Cloud SDK

If you specify a database role when you submit a query, DML, or a row operation, Spanner checks fine-grained access control privileges. If the check fails, Spanner does not check for database-level IAM permissions, and the operation fails.

If you don't specify a database role, Spanner checks database-level IAM permissions, and if the checks succeed, your session proceeds with your database-level permissions.

Use these methods to specify a database role when accessing a Spanner database:

Console

1. Select a database, and then on the database Overview page, click the Change database role (pencil) icon adjacent to the Current role field.

   By default, when a fine-grained access control user logs in, this field has the value public. For information about the public system role, see Fine-grained access control system roles.

   Note: As stated earlier, if a fine-grained access control user has database-level IAM permissions, the Current role field isn't shown.

2. In the Change database role dialog, select another role from the list of available roles.

3. Click Update.

   The Current role field shows the new role.

gcloud

• Add the --database-role option to the gcloud spanner databases execute-sql command, as follows:

  gcloud spanner databases execute-sql DATABASE_NAME \
  --instance=INSTANCE_NAME \
  --sql="SELECT * from TABLE_NAME;" \
  --database-role=ROLE_NAME

Client libraries

C++

void ReadDataWithDatabaseRole(std::string const& project_id,
                              std::string const& instance_id,
                              std::string const& database_id,
                              std::string const& role) {
  namespace spanner = ::google::cloud::spanner;
  auto client = spanner::Client(spanner::MakeConnection(
      spanner::Database(project_id, instance_id, database_id),
      google::cloud::Options{}.set<spanner::SessionCreatorRoleOption>(role)));
  spanner::SqlStatement select_star("SELECT * FROM Singers");
  auto rows = client.ExecuteQuery(std::move(select_star));
  using RowType =
      std::tuple<std::int64_t, std::string, std::string, spanner::Bytes>;
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << ", "
              << "FirstName: " << std::get<1>(*row) << ", "
              << "LastName: " << std::get<2>(*row) << "\n";
  }
}

C#

using Google.Cloud.Spanner.Data;
using System.Collections.Generic;
using System.Threading.Tasks;

public class ReadDataWithDatabaseRoleAsyncSample
{
    public class Singer
    {
        public int SingerId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

    public async Task<List<Singer>> ReadDataWithDatabaseRoleAsync(string projectId, string instanceId, string databaseId, string databaseRole)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        string tableName = "Singers";

        var spannerConnectionStringBuilder = new SpannerConnectionStringBuilder
        {
            ConnectionString = connectionString,
            DatabaseRole = databaseRole
        };
        using var connection = new SpannerConnection(spannerConnectionStringBuilder);
        var createSelectCmd = connection.CreateSelectCommand($"SELECT * FROM {tableName}");
        using var reader = await createSelectCmd.ExecuteReaderAsync();
        var singers = new List<Singer>();
        while (await reader.ReadAsync())
        {
            singers.Add(new Singer
            {
                SingerId = reader.GetFieldValue<int>("SingerId"),
                FirstName = reader.GetFieldValue<string>("FirstName"),
                LastName = reader.GetFieldValue<string>("LastName"),
            });
        }
        return singers;
    }
}

Go

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

func readDataWithDatabaseRole(w io.Writer, db string, databaseRole string) error {
	// databaseRole = "parent"
	ctx := context.Background()
	cfg := spanner.ClientConfig{
		DatabaseRole: databaseRole,
	}
	client, err := spanner.NewClientWithConfig(ctx, db, cfg)
	if err != nil {
		return err
	}
	defer client.Close()

	// Read all albums.
	iter := client.Single().Read(ctx, "Albums", spanner.AllKeys(),
		[]string{"SingerId", "AlbumId", "AlbumTitle"})
	defer iter.Stop()
	for {
		row, err := iter.Next()
		if err == iterator.Done {
			return nil
		}
		if err != nil {
			return err
		}
		var singerID, albumID int64
		var albumTitle string
		if err := row.Columns(&singerID, &albumID, &albumTitle); err != nil {
			return err
		}
		fmt.Fprintf(w, "%d %d %s\n", singerID, albumID, albumTitle)
	}
}

Java

import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.KeySet;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import java.util.Arrays;

public class ReadDataWithDatabaseRole {

  static void readDataWithDatabaseRole() {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "my-project";
    String instanceId = "my-instance";
    String databaseId = "my-database";
    String role = "my-role";
    readDataWithDatabaseRole(projectId, instanceId, databaseId, role);
  }

  static void readDataWithDatabaseRole(
      String projectId, String instanceId, String databaseId, String role) {
    try (Spanner spannerWithRole =
        SpannerOptions.newBuilder()
            .setProjectId(projectId)
            .setDatabaseRole(role)
            .build()
            .getService()) {
      DatabaseClient dbClient =
          spannerWithRole.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
      ResultSet resultSet =
          dbClient
              .singleUse()
              .read(
                  "Singers",
                  KeySet.all(),
                  Arrays.asList("SingerId", "FirstName", "LastName"));
      while (resultSet.next()) {
        System.out.printf("SingerId: %d\n", resultSet.getLong(0));
        System.out.printf("FirstName: %s\n", resultSet.getString(1));
        System.out.printf("LastName: %s\n", resultSet.getString(2));
      }
    }
  }
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// const projectId = 'my-project-id';
// Imports the Google Cloud Spanner client library
const {Spanner} = require('@google-cloud/spanner');

// Instantiates a client
const spanner = new Spanner({
  projectId: projectId,
});

async function readDataWithDatabaseRole() {
  // Gets a reference to a Cloud Spanner instance and database.
  const instance = spanner.instance(instanceId);
  // Connect to a database using the 'parent' database role. This means that the connection will only have the permissions that have explicitly been granted to the 'parent' role.
  const options = {
    databaseRole: 'parent',
  };
  const database = instance.database(databaseId, options);

  try {
    const query = {
      sql: 'SELECT SingerId, FirstName, LastName FROM Singers',
    };
    const [rows] = await database.run(query);

    for (const row of rows) {
      const json = row.toJSON();

      console.log(
        `SingerId: ${json.SingerId}, FirstName: ${json.FirstName}, LastName: ${json.LastName}`,
      );
    }
  } catch (err) {
    console.error('ERROR:', err);
  } finally {
    // Close the database when finished.
    await database.close();
  }
}
readDataWithDatabaseRole();

PHP

use Google\Cloud\Spanner\SpannerClient;

/**
 * Read database with a database role.
 * Example:
 * ```
 * read_data_with_database_role($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function read_data_with_database_role(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $databaseRole = 'new_parent';
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId, ['databaseRole' => $databaseRole]);
    $results = $database->execute('SELECT * FROM Singers');

    foreach ($results as $row) {
        printf('SingerId: %s, Firstname: %s, LastName: %s' . PHP_EOL, $row['SingerId'], $row['FirstName'], $row['LastName']);
    }
}

Python

# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
role = "new_parent"
database = instance.database(database_id, database_role=role)

with database.snapshot() as snapshot:
    results = snapshot.execute_sql("SELECT * FROM Singers")
    for row in results:
        print("SingerId: {}, FirstName: {}, LastName: {}".format(*row))

Ruby

require "google/cloud/spanner"

def spanner_read_data_with_database_role project_id:, instance_id:, database_id:
  # project_id  = "Your Google Cloud project ID"
  # instance_id = "Your Spanner instance ID"
  # database_id = "Your Spanner database ID"

  role = "new_parent"
  spanner = Google::Cloud::Spanner.new project: project_id
  client = spanner.client instance_id, database_id, database_role: role

  result = client.execute_sql "SELECT * FROM Singers"

  result.rows.each do |row|
    puts "SingerId: #{row[:SingerId]}"
    puts "FirstName: #{row[:FirstName]}"
    puts "LastName: #{row[:LastName]}"
  end
end