doc: add MutableCredentials Example #4382
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| Original file line number | Diff line number | Diff line change | ||||||||
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| @@ -0,0 +1,98 @@ | ||||||||||
| /* | ||||||||||
| * Copyright 2026 Google LLC | ||||||||||
| * | ||||||||||
| * Licensed 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. | ||||||||||
| */ | ||||||||||
|
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| package com.example.spanner; | ||||||||||
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| // [START spanner_mutable_credentials] | ||||||||||
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| import com.google.auth.oauth2.ServiceAccountCredentials; | ||||||||||
| import com.google.cloud.spanner.MutableCredentials; | ||||||||||
| import com.google.cloud.spanner.Spanner; | ||||||||||
| import com.google.cloud.spanner.SpannerOptions; | ||||||||||
| import com.google.cloud.spanner.admin.database.v1.DatabaseAdminClient; | ||||||||||
| import java.io.FileInputStream; | ||||||||||
| import java.io.IOException; | ||||||||||
| import java.nio.file.Files; | ||||||||||
| import java.nio.file.Path; | ||||||||||
| import java.nio.file.Paths; | ||||||||||
| import java.nio.file.attribute.FileTime; | ||||||||||
| import java.util.concurrent.Executors; | ||||||||||
| import java.util.concurrent.ScheduledExecutorService; | ||||||||||
| import java.util.concurrent.ThreadFactory; | ||||||||||
| import java.util.concurrent.TimeUnit; | ||||||||||
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| public class MutableCredentialsExample { | ||||||||||
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| static void createClientWithMutableCredentials() throws IOException { | ||||||||||
| final String credentialsPath = "location_of_service_account_credential_json"; | ||||||||||
| Path path = Paths.get(credentialsPath); | ||||||||||
| // Use an array to hold the mutable lastModifiedTime so it can be accessed in the lambda | ||||||||||
| FileTime[] lastModifiedTime = new FileTime[] {Files.getLastModifiedTime(path)}; | ||||||||||
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| // 1 - create service account credentials | ||||||||||
| ServiceAccountCredentials serviceAccountCredentials; | ||||||||||
| try (FileInputStream is = new FileInputStream(credentialsPath)) { | ||||||||||
| serviceAccountCredentials = ServiceAccountCredentials.fromStream(is); | ||||||||||
| } | ||||||||||
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| // 2 - wrap credentials from step 1 in a MutableCredentials instance | ||||||||||
| MutableCredentials mutableCredentials = new MutableCredentials(serviceAccountCredentials); | ||||||||||
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| // 3 - set credentials on your SpannerOptions builder to your mutableCredentials | ||||||||||
| SpannerOptions options = SpannerOptions.newBuilder().setCredentials(mutableCredentials).build(); | ||||||||||
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| // 4 - include logic for when/how to update your mutableCredentials | ||||||||||
| // In this example we'll use a SchedulerExecutorService to periodically check for updates | ||||||||||
| ThreadFactory daemonThreadFactory = | ||||||||||
| runnable -> { | ||||||||||
| Thread thread = new Thread(runnable, "spanner-mutable-credentials-rotator"); | ||||||||||
| thread.setDaemon(true); | ||||||||||
| return thread; | ||||||||||
| }; | ||||||||||
| ScheduledExecutorService executorService = | ||||||||||
| Executors.newSingleThreadScheduledExecutor(daemonThreadFactory); | ||||||||||
| executorService.scheduleAtFixedRate( | ||||||||||
| () -> { | ||||||||||
| try { | ||||||||||
| FileTime currentModifiedTime = Files.getLastModifiedTime(path); | ||||||||||
| if (currentModifiedTime.compareTo(lastModifiedTime[0]) > 0) { | ||||||||||
| lastModifiedTime[0] = currentModifiedTime; | ||||||||||
|
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Contributor
There was a problem hiding this comment. As part of refactoring to use
Suggested change
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| try (FileInputStream is = new FileInputStream(credentialsPath)) { | ||||||||||
| ServiceAccountCredentials credentials = ServiceAccountCredentials.fromStream(is); | ||||||||||
| mutableCredentials.updateCredentials(credentials); | ||||||||||
| } | ||||||||||
| } | ||||||||||
| } catch (IOException e) { | ||||||||||
| System.err.println("Failed to check or update credentials: " + e.getMessage()); | ||||||||||
| } | ||||||||||
| }, | ||||||||||
| 15, | ||||||||||
| 15, | ||||||||||
| TimeUnit.MINUTES); | ||||||||||
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| // 5. Use the client | ||||||||||
| try (Spanner spanner = options.getService(); | ||||||||||
| DatabaseAdminClient databaseAdminClient = spanner.createDatabaseAdminClient()) { | ||||||||||
| // Perform operations... | ||||||||||
| // long running client operations will always use the latest credentials wrapped in | ||||||||||
| // mutableCredentials | ||||||||||
| } finally { | ||||||||||
| // Ensure the executor is shut down when the application exits or the client is closed | ||||||||||
| executorService.shutdown(); | ||||||||||
| } | ||||||||||
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Contributor
There was a problem hiding this comment. This example is intended to demonstrate credential updates for a long-running client, but the To make the example more illustrative, consider adding a // 5. Use the client
try (Spanner spanner = options.getService();
DatabaseAdminClient databaseAdminClient = spanner.createDatabaseAdminClient()) {
// Perform operations...
// long running client operations will always use the latest credentials wrapped in
// mutableCredentials.
// This example demonstrates this by keeping the client alive for 60 seconds.
System.out.println("Client created. It will remain active for 60 seconds.");
try {
TimeUnit.SECONDS.sleep(60);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
System.out.println("60 seconds passed. Closing client.");
} finally {
// Ensure the executor is shut down when the application exits or the client is closed
executorService.shutdown();
} |
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| } | ||||||||||
| } | ||||||||||
| // [END spanner_mutable_credentials] | ||||||||||
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For better clarity and to use modern Java concurrency utilities, consider using
java.util.concurrent.atomic.AtomicReferenceinstead of a single-element array to hold a mutable reference. This makes the intent of sharing a mutable object with the lambda more explicit. This change should be applied along with an update to the lambda that uses this variable.