(CLI): hotswap support for API Gateway

[misterjoshua]

Description

I'd like the CDK CLI to hotswap the following API Gateway Method constituents:

• Method requestParameters
• Integration requestParameters
• Integration requestTemplates
• Integration responseTemplates
• Method methodResponses

Use Case

Development of service-to-service integrations with AwsIntegration, especially when using substantial VTL code.

Proposed Solution

We should hotswap these fields so that incremental development doesn't require substantial CloudFormation waits between changes.

Other information

Example of a non-trivial service-to-service integration:

const AMZ_JSON_1_0 = 'application/x-amz-json-1.0';
const APPLICATION_JSON = 'application/json';

const requestModel = new aws_apigateway.Model(this, 'Model', {
  restApi: resource.api,
  schema: {
    type: aws_apigateway.JsonSchemaType.OBJECT,
    properties: {
      test: { type: aws_apigateway.JsonSchemaType.STRING },
      env: { type: aws_apigateway.JsonSchemaType.STRING },
      result: { type: [aws_apigateway.JsonSchemaType.OBJECT, aws_apigateway.JsonSchemaType.STRING] },
    },
    required: [
      'env',
      'test',
      'result',
    ],
  },
});

new aws_apigateway.Method(this, 'PostMethod', {
  httpMethod: 'POST',
  resource: resource,
  options: {
    methodResponses: [{ statusCode: '200' }],
    requestModels: {
      [APPLICATION_JSON]: requestModel,
    },
    requestValidatorOptions: {
      validateRequestBody: true,
    },
  },
  integration: new aws_apigateway.AwsIntegration({
    service: 'dynamodb',
    action: 'PutItem',
    options: {
      credentialsRole,
      requestTemplates: {
        [APPLICATION_JSON]: [
          "#set ($env = $input.path('$.env'))",
          "#set ($test = $input.path('$.test'))",
          "#set ($timeId = $context.requestTimeEpoch + '#' + $context.requestId)",
          JSON.stringify({
            TableName: table.tableName,
            Item: {
              // Test results in an environment by date
              PK: { S: 'ENV#$util.escapeJavaScript($env)' },
              SK: { S: 'TEST#$util.escapeJavaScript($test)#$timeId' },
              // Test results across environments by date
              GSI1PK: { S: 'TEST#$util.escapeJavaScript($test)' },
              GSI1SK: { S: 'ENV#$util.escapeJavaScript($env)#$timeId' },
              // Data
              env: { S: '$util.escapeJavaScript($env)' },
              test: { S: '$util.escapeJavaScript($test)' },
              result: { S: "$util.escapeJavaScript($input.json('$.result'))" },
            },
          }),
        ].join('\n'),
      },
      passthroughBehavior: aws_apigateway.PassthroughBehavior.WHEN_NO_MATCH,
      integrationResponses: [{
        statusCode: '200',
        responseTemplates: {
          [AMZ_JSON_1_0]: JSON.stringify({
            requestId: '$context.requestId',
          }),
        },
      }],
    },
  }),
});

new aws_apigateway.Method(this, 'GetByEnvMethod', {
  httpMethod: 'GET',
  resource: resource,
  options: {
    methodResponses: [{
      statusCode: '200',
    }],
    requestParameters: {
      'method.request.path.env': true,
    },
  },
  integration: new aws_apigateway.AwsIntegration({
    service: 'dynamodb',
    action: 'Query',
    options: {
      credentialsRole,
      requestParameters: {
        'integration.request.path.env': 'method.request.path.env',
      },
      requestTemplates: {
        [APPLICATION_JSON]: [
          "#set ($env = $input.params('env'))",
          '#set ($limit = 2)',
          JSON.stringify({
            TableName: table.tableName,
            Limit: '$limit',
            KeyConditionExpression: 'PK = :PK',
            ExpressionAttributeValues: {
              ':PK': { S: 'ENV#$util.escapeJavaScript($env)' },
            },
          }),
        ].join('\n'),
      },
      passthroughBehavior: aws_apigateway.PassthroughBehavior.WHEN_NO_MATCH,
      integrationResponses: [{
        statusCode: '200',
        responseTemplates: {
          [AMZ_JSON_1_0]: [
            "#set($root = $input.path('$'))",
            '{',
            // eslint-disable-next-line quotes
            `  "Count": $root.Count,`,
            '  "Results": [',
            '#foreach($item in $root.Items)',
            '#set($env = $item.env.S)',
            '#set($test = $item.test.S)',
            '#set($result = $item.result.S)',
            '    {',
            '      "env": "$util.escapeJavaScript($env)",',
            '      "test": "$util.escapeJavaScript($test)",',
            '      "result": $result', // Provide the JSON directly.
            '    }#if($foreach.hasNext),#end',
            '#end',
            '',
            '  ]',
            '}',
          ].join('\n'),
        },
      }],
    },
  }),
});

Acknowledge

• [ ] I may be able to implement this feature request
• [ ] This feature might incur a breaking change

[skinny85]

Thanks for opening the issue @misterjoshua!