This is the AWS CDK v2 Developer Guide. The older CDK v1 entered maintenance on June 1, 2022 and ended support on June 1, 2023.

# Advanced CDK Toolkit Library examples
<a name="toolkit-library-examples"></a>

Learn how to use advanced features of the AWS CDK Toolkit Library through practical examples. This guide provides detailed code samples for error handling, deployment monitoring, and cloud assembly management that build upon the basic concepts covered in other sections.

## Integrating features
<a name="toolkit-library-examples-integration"></a>

The following example demonstrates how to combine cloud assembly sources, custom io host implementation, and deployment options:

```
import { Toolkit, StackSelectionStrategy, IIoHost } from '@aws-cdk/toolkit-lib';

async function deployApplication(appPath, environment, options = {}) {
  // Create toolkit with custom message handling
  const toolkit = new Toolkit({
    ioHost: {
      notify: async (msg) => {
        // Add environment to all messages
        console.log(`[${environment}][${msg.time}] ${msg.level}: ${msg.message}`);
      },
      requestResponse: async (msg) => {
        // In production environments, use default responses
        if (environment === 'production') {
          console.log(`Auto-approving for production: ${msg.message}`);
          return msg.defaultResponse;
        }

        // For other environments, implement custom approval logic
        return promptForApproval(msg);
      }
    } as IIoHost
  });

  try {
    // Create cloud assembly source from the CDK app
    console.log(`Creating cloud assembly source from ${appPath}`);
    const cloudAssemblySource = await toolkit.fromCdkApp(appPath);

    // Synthesize the cloud assembly
    console.log(`Synthesizing cloud assembly`);
    const cloudAssembly = await toolkit.synth(cloudAssemblySource);

    try {
      // Deploy with environment-specific options
      console.log(`Deploying to ${environment} environment`);
      return await toolkit.deploy(cloudAssembly, {
        stacks: options.stacks || { strategy: StackSelectionStrategy.ALL_STACKS },
        parameters: options.parameters || {},
        tags: {
          Environment: environment,
          DeployedBy: 'CDK-Toolkit-Library',
          DeployTime: new Date().toISOString()
        }
      });
    } finally {
      // Always dispose when done
      await cloudAssembly.dispose();
    }
  } catch (error) {
    console.error(`Deployment to ${environment} failed:`, error);
    throw error;
  }
}

// Example usage
await deployApplication('ts-node app.ts', 'staging', {
  parameters: {
    MyStack: {
      InstanceType: 't3.small'
    }
  }
});
```

## Tracking deployment progress
<a name="toolkit-library-examples-progress"></a>

Track deployment progress with detailed status updates:

```
import { Toolkit, StackSelectionStrategy, IIoHost } from '@aws-cdk/toolkit-lib';

// Create a progress tracker
class DeploymentTracker {
  private startTime: Date;
  private resources = new Map<string, string>();

  constructor() {
    this.startTime = new Date();
  }

  onStackEvent(stackName: string, event: string, timestamp: string) {
    // Calculate elapsed time if needed, or use the provided timestamp
    const elapsed = (new Date().getTime() - this.startTime.getTime()) / 1000;
    console.log(`[${timestamp}] (${elapsed.toFixed(1)}s elapsed) Stack ${stackName}: ${event}`);
  }

  onResourceEvent(resourceId: string, status: string) {
    this.resources.set(resourceId, status);
    this.printProgress();
  }

  private printProgress() {
    console.log('\nResource Status:');
    for (const [id, status] of this.resources.entries()) {
      console.log(`- ${id}: ${status}`);
    }
    console.log();
  }
}

// Use the tracker with the toolkit
const tracker = new DeploymentTracker();
const toolkit = new Toolkit({
  ioHost: {
    notify: async (msg) => {
      if (msg.code.startsWith('CDK_DEPLOY')) {
        // Track deployment events
        if (msg.data && 'stackName' in msg.data) {
          tracker.onStackEvent(msg.data.stackName, msg.message, msg.time);
        }
      } else if (msg.code.startsWith('CDK_RESOURCE')) {
        // Track resource events
        if (msg.data && 'resourceId' in msg.data) {
          tracker.onResourceEvent(msg.data.resourceId, msg.message);
        }
      }
    }
  } as IIoHost
});

// Example usage with progress tracking
async function deployWithTracking(cloudAssemblySource: any) {
  try {
    // Synthesize the cloud assembly
    const cloudAssembly = await toolkit.synth(cloudAssemblySource);

    try {
      // Deploy using the cloud assembly
      await toolkit.deploy(cloudAssembly, {
        stacks: {
          strategy: StackSelectionStrategy.ALL_STACKS
        }
      });
    } finally {
      // Always dispose when done
      await cloudAssembly.dispose();
    }
  } catch (error) {
    // Display the error message
    console.error("Operation failed:", error.message);
    throw error;
  }
}
```

## Handling errors with recovery
<a name="toolkit-library-examples-error"></a>

Implement robust error handling with recovery strategies:

```
import { Toolkit, ToolkitError, StackSelectionStrategy } from '@aws-cdk/toolkit-lib';

async function deployWithRetry(toolkit: Toolkit, cloudAssemblySource: any) {
  try {
    // Synthesize the cloud assembly
    const cloudAssembly = await toolkit.synth(cloudAssemblySource);

    try {
      // Deploy using the cloud assembly
      await toolkit.deploy(cloudAssembly, {
        stacks: {
          strategy: StackSelectionStrategy.ALL_STACKS
        }
      });
    } finally {
      // Always dispose when done
      await cloudAssembly.dispose();
    }
  } catch (error) {
    // Simply show the error to the user
    console.error("Operation failed:", error.message);
    throw error;
  }
}

// Example usage
try {
  await deployWithRetry(toolkit, cloudAssemblySource);
} catch (error) {
  console.error("Operation failed:", error.message);
  process.exit(1);
}
```

## Integrating with CI/CD pipelines
<a name="toolkit-library-examples-cicd"></a>

Integrate the CDK Toolkit Library into a CI/CD pipeline:

```
import { Toolkit, StackSelectionStrategy, IIoHost } from '@aws-cdk/toolkit-lib';
import * as fs from 'fs';
import * as path from 'path';

async function cicdDeploy() {
  // Create a non-interactive toolkit for CI/CD environments
  const toolkit = new Toolkit({
    ioHost: {
      notify: async (msg) => {
        // Write to both console and log file
        const logMessage = `${msg.time} [${msg.level}] ${msg.message}`;
        console.log(logMessage);

        // Append to deployment log file
        fs.appendFileSync('deployment.log', logMessage + '\n');
      },
      requestResponse: async (msg) => {
        // Always use default responses in CI/CD
        console.log(`Auto-responding to: ${msg.message} with: ${msg.defaultResponse}`);
        return msg.defaultResponse;
      }
    } as IIoHost
  });

  // Determine environment from CI/CD variables
  const environment = process.env.DEPLOYMENT_ENV || 'development';

  // Load environment-specific parameters
  const paramsPath = path.join(process.cwd(), `params.${environment}.json`);
  const parameters = fs.existsSync(paramsPath)
    ? JSON.parse(fs.readFileSync(paramsPath, 'utf8'))
    : {};

  try {
    // Use pre-synthesized cloud assembly from build step
    const cloudAssemblySource = await toolkit.fromAssemblyDirectory('cdk.out');

    // Synthesize the cloud assembly
    const cloudAssembly = await toolkit.synth(cloudAssemblySource);

    try {
      // Deploy with CI/CD specific options
      const result = await toolkit.deploy(cloudAssembly, {
        stacks: { strategy: StackSelectionStrategy.ALL_STACKS },
        parameters,
        tags: {
          Environment: environment,
          BuildId: process.env.BUILD_ID || 'unknown',
          CommitHash: process.env.COMMIT_HASH || 'unknown'
        }
      });

      // Write outputs to a file for subsequent pipeline steps
      fs.writeFileSync(
        'stack-outputs.json',
        JSON.stringify(result.outputs, null, 2)
      );

      return result;
    } finally {
      // Always dispose when done
      await cloudAssembly.dispose();
    }
  } catch (error) {
    // Display the error message
    console.error("Operation failed:", error.message);
    process.exit(1);
  }
}

// Run the CI/CD deployment
cicdDeploy().then(() => {
  console.log('CI/CD deployment completed successfully');
});
```

## Additional resources
<a name="toolkit-library-examples-resources"></a>

For more detailed information on specific components used in these examples, refer to:
+  [Managing cloud assembly sources](toolkit-library-configure-ca.md) - Learn how to create and manage cloud assembly sources.
+  [Configuring messages and interactions](toolkit-library-configure-messages.md) - Detailed guide on customizing the `IIoHost` interface.