run-workflow-function index.js

index.js

const projectId = process.env.PROJECT_ID;

/**
 * Run Workflow Cloud Function
 */
exports.runWorkflow = async (req, res) => {
  if (req.method !== 'POST') {
    return res.status(405).send('Only POST method is allowed');
  }
  const workflowsAPI = await callWorkflowsAPI();
  if (!workflowsAPI.success) {
    return res.status(400).send(`Error running workflow. Result: ${workflowsAPI.result}`)
  }
  res.send(`Result: ${workflowsAPI.result}`);
};

const {ExecutionsClient} = require('@google-cloud/workflows');
const client = new ExecutionsClient();

/**
 * Calls the Workflow API and waits for the execution result.
 */
async function callWorkflowsAPI() {
  const location = 'us-central1';
  const workflow = 'myFirstWorkflow';
  
  // Execute workflow
  try {
    const createExecutionRes = await client.createExecution({
      parent: client.workflowPath(projectId, location, workflow),
    });
    const executionName = createExecutionRes[0].name;
    console.log(`Created execution: ${executionName}`);

    // Wait for execution to finish, then print results.
    let executionFinished = false;
    let backoffDelay = 1000; // Start wait with delay of 1,000 ms
    console.log('Poll every second for result...');
    while (!executionFinished) {
      const [execution] = await client.getExecution({
        name: executionName,
      });
      executionFinished = execution.state !== 'ACTIVE';

      // If we haven't seen the result yet, wait a second.
      if (!executionFinished) {
        console.log('- Waiting for results...');
        await new Promise(resolve => {
          setTimeout(resolve, backoffDelay);
        });
        backoffDelay *= 2; // Double the delay to provide exponential backoff.
      } else {
        console.log(`Execution finished with state: ${execution.state}`);
        console.log(execution.result);
        return {
          success: true,
          result: execution.result
        };
      }
    }
  } catch (e) {
    console.error(`Error executing workflow: ${e}`);
    return {
      success: false,
    };
  }
}