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Ace Nassri
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feat(functions): add infinite retries sample (GoogleCloudPlatform#1260)
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‎functions/tips_infinite_retries/composer.json

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{
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"require": {
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"google/cloud-functions-framework": "^0.7.1"
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},
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"require-dev": {
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"google/cloud-pubsub": "^1.29",
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"google/cloud-logging": "^1.21"
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}
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}

‎functions/tips_infinite_retries/index.php

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/**
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* Copyright 2020 Google LLC.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// [START functions_tips_infinite_retries]
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/**
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* This function shows an example method for avoiding infinite retries in
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* Google Cloud Functions. By default, functions configured to automatically
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* retry execution on failure will be retried indefinitely - causing an
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* infinite loop. To avoid this, we stop retrying executions (by not throwing
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* exceptions) for any events that are older than a predefined threshold.
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*/
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use Google\CloudFunctions\CloudEvent;
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function avoidInfiniteRetries(CloudEvent $event): string
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{
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$log = fopen(getenv('LOGGER_OUTPUT') ?: 'php://stderr', 'wb');
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$eventId = $event->getId();
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// The maximum age of events to process.
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$maxAge = 60 * 3; // 3 minutes, in seconds
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// The age of the event being processed.
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$eventAge = time() - strtotime($event->getTime());
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// Ignore events that are too old
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if ($eventAge > $maxAge) {
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fwrite($log, 'Dropping event ' . $eventId . ' with age ' . $eventAge . ' seconds' . PHP_EOL);
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return '';
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}
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// Do what the function is supposed to do
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fwrite($log, 'Processing event: ' . $eventId . ' with age ' . $eventAge . ' seconds' . PHP_EOL);
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// infinite_retries failed function executions
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$failed = true;
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if ($failed) {
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throw new Exception('Event ' . $eventId . ' failed; retrying...');
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}
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return '';
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}
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// [END functions_tips_infinite_retries]

‎functions/tips_infinite_retries/phpunit.xml.dist

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xml version="1.0" encoding="UTF-8"?>
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<phpunit bootstrap="../../testing/bootstrap.php" convertWarningsToExceptions="false">
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<testsuites>
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<testsuite name="Cloud Functions Tips Avoid Infinite Retries Test Suite">
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<directory>testdirectory>
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testsuite>
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testsuites>
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<logging>
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<log type="coverage-clover" target="build/logs/clover.xml"/>
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logging>
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<filter>
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<whitelist>
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<directory suffix=".php">.directory>
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<exclude>
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<directory>./vendordirectory>
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exclude>
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whitelist>
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filter>
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phpunit>

‎functions/tips_infinite_retries/test/DeployTest.php

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/**
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* Copyright 2020 Google LLC.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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declare(strict_types=1);
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namespace Google\Cloud\Samples\Functions\TipsInfiniteRetries\Test;
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use Google\Cloud\Logging\LoggingClient;
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use Google\Cloud\TestUtils\CloudFunctionDeploymentTrait;
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use Google\Cloud\TestUtils\EventuallyConsistentTestTrait;
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use Google\Cloud\TestUtils\GcloudWrapper\CloudFunction;
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use Google\Cloud\PubSub\PubSubClient;
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use PHPUnit\Framework\TestCase;
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use PHPUnit\Framework\ExpectationFailedException;
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/**
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* Class DeployTest.
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*
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* This test is not run by the CI system.
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*
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* To skip deployment of a new function, run with "GOOGLE_SKIP_DEPLOYMENT=true".
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* To skip deletion of the tested function, run with "GOOGLE_KEEP_DEPLOYMENT=true".
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*/
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class DeployTest extends TestCase
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{
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use CloudFunctionDeploymentTrait;
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use EventuallyConsistentTestTrait;
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private static $entryPoint = 'avoidInfiniteRetries';
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/* var string */
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private static $projectId;
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/* var string */
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private static $topicName;
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/** @var LoggingClient */
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private static $loggingClient;
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public function testTipsRetry(): void
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{
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// Send Pub/Sub message.
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$this->publishMessage();
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// Give event and log systems a head start.
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// If log retrieval fails to find logs for our function within retry limit, increase sleep time.
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sleep(30);
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$fiveMinAgo = date(\DateTime::RFC3339, strtotime('-5 minutes'));
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$this->processFunctionLogs(self::$fn, $fiveMinAgo, function (\Iterator $logs) {
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// Concatenate all relevant log messages.
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$actual = '';
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foreach ($logs as $log) {
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$info = $log->info();
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$actual .= $info['textPayload'];
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}
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// Check that multiple invocations of the function have occurred.
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$retryCount = substr_count($actual, 'retrying...');
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$this->assertGreaterThan(1, $retryCount);
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// Check that the function has stopped retrying
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$this->assertContains('Dropping event', $actual);
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});
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}
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private function publishMessage(): void
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{
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// Construct Pub/Sub message
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$message = json_encode(['retry' => true]);
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// Publish a message to the function.
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$pubsub = new PubSubClient([
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'projectId' => self::$projectId,
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]);
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$topic = $pubsub->topic(self::$topicName);
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$topic->publish(['data' => $message]);
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}
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/**
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* Retrieve and process logs for the defined function.
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*
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* @param CloudFunction $fn function whose logs should be checked.
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* @param string $startTime RFC3339 timestamp marking start of time range to retrieve.
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* @param callable $process callback function to run on the logs.
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*/
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private function processFunctionLogs(CloudFunction $fn, string $startTime, callable $process)
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{
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$projectId = self::requireEnv('GOOGLE_PROJECT_ID');
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if (empty(self::$loggingClient)) {
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self::$loggingClient = new LoggingClient([
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'projectId' => $projectId
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]);
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}
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// Define the log search criteria.
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$logFullName = 'projects/' . $projectId . '/logs/cloudfunctions.googleapis.com%2Fcloud-functions';
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$filter = sprintf(
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'logName="%s" resource.labels.function_name="%s" timestamp>="%s"',
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$logFullName,
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$fn->getFunctionName(),
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$startTime
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);
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echo "\nRetrieving logs [$filter]... (this may take a minute or two)\n";
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// Check for new logs for the function.
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$attempt = 1;
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$this->runEventuallyConsistentTest(function () use ($filter, $process, &$attempt) {
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$entries = self::$loggingClient->entries(['filter' => $filter]);
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// If no logs came in try again.
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if (empty($entries->current())) {
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echo 'Logs not found, attempting retry #' . $attempt++ . PHP_EOL;
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throw new ExpectationFailedException('Log Entries not available');
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}
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echo 'Processing logs...' . PHP_EOL;
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$process($entries);
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}, $retries = 10);
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}
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/**
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* Deploy the Cloud Function, called from DeploymentTrait::deployApp().
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*
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* Overrides CloudFunctionDeploymentTrait::doDeploy().
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*/
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private static function doDeploy()
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{
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self::$projectId = self::requireEnv('GOOGLE_CLOUD_PROJECT');
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self::$topicName = self::requireEnv('FUNCTIONS_TOPIC');
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return self::$fn->deploy(['--retry' => ''], '--trigger-topic=' . self::$topicName);
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}
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}

‎functions/tips_infinite_retries/test/IntegrationTest.php

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/**
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* Copyright 2020 Google LLC.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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declare(strict_types=1);
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namespace Google\Cloud\Samples\Functions\TipsInfiniteRetries\Test;
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use PHPUnit\Framework\TestCase;
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use Google\Cloud\TestUtils\CloudFunctionLocalTestTrait;
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/**
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* Class IntegrationTest.
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*
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* Integration Test for helloGCS.
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*/
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class IntegrationTest extends TestCase
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{
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use CloudFunctionLocalTestTrait;
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/** @var string */
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private static $entryPoint = 'avoidInfiniteRetries';
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/** @var string */
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private static $functionSignatureType = 'cloudevent';
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public function dataProvider()
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{
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return [
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[
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'cloudevent' => [
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'id' => 'new-event',
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'source' => 'pubsub.googleapis.com',
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'specversion' => '1.0',
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'type' => 'google.cloud.pubsub.topic.v1.messagePublished',
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'time' => gmdate('c', strtotime('+20 minutes'))
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],
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'data' => [],
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'statusCode' => '500',
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'expected' => 'Event new-event failed; retrying...',
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'label' => 'Should throw an exception to trigger a retry'
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],
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[
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'cloudevent' => [
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'id' => 'old-event',
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'source' => 'pubsub.googleapis.com',
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'specversion' => '1.0',
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'type' => 'google.cloud.pubsub.topic.v1.messagePublished',
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'time' => gmdate('c', strtotime('-20 minutes'))
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],
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'data' => [
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'data' => [],
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],
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'statusCode' => '200',
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'expected' => 'Dropping event old-event with age',
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'label' => 'Should not throw an exception if event is too old'
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],
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];
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}
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/**
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* @dataProvider dataProvider
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*/
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public function testLimitInfiniteRetries(array $cloudevent, array $data, string $statusCode, string $expected, string $label): void
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{
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// Prepare the HTTP headers for a CloudEvent.
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$cloudEventHeaders = [];
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foreach ($cloudevent as $key => $value) {
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$cloudEventHeaders['ce-' . $key] = $value;
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}
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// Send an HTTP request using CloudEvent metadata.
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$resp = $this->client->request('POST', '/', [
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'body' => json_encode($data),
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'headers' => $cloudEventHeaders + [
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// Instruct the function framework to parse the body as JSON.
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'content-type' => 'application/json'
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],
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]);
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// The Cloud Function logs all data to stderr.
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$actual = self::$localhost->getIncrementalErrorOutput();
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// Confirm the status code.
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$this->assertEquals(
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$statusCode,
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$resp->getStatusCode(),
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$label . ' status code'
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);
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// Verify the function's behavior is correct.
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$this->assertContains($expected, $actual, $label . ' contains');
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}
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}

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