AWS - AppConfig - Feature flags - CDK V1 - AppConfig Feature Flags Helper: Malformed 'Content' provided

Question

I am trying to create an AWS AppConfig app, configuration profile, environment, hosted configuration, deployment strategy and the deployment constructs from CDK V1 (Node.js).

I am following @aws-cdk_aws-appconfig.CfnHostedConfigurationVersion AWS docs. Unfortunately, no specification has been given on content syntax.

While performing cdk deploy it gives an error:

MyCfnHostedConfigurationVersion Error invoking extension AppConfig Feature Flags Helper: Malformed 'Content' provided (Service: AmazonAppConfig; Status Code: 400; Error Code: BadRequestException; Request ID: f9496e9f-db25-438b-a7bb-f030351eb251; Proxy: null)

I am trying to apply Aleksander Gurin's solution. I am using CDK V1 (Node.Js).

Code I have tried so far. I expected it to create the AppConfig profile of feature flags type.

//Create an application
const cfnAppConfigApplication = new appconfig.CfnApplication(this, 'MyCfnApplication', { name: 'document-vault-app-config-app', description: 'App to maintain environment variables for Document Vault.',});
//Create an environment
const cfnEnvironment = new appconfig.CfnEnvironment(this, 'MyCfnEnvironment', {
  applicationId: cfnAppConfigApplication.ref,
  name: props.environmentName,
  description: 'Environment to deploy the configuration to.',
});

//Create a configuration profile
const cfnConfigurationProfile = new appconfig.CfnConfigurationProfile(this, 'MyCfnConfigurationProfile', {
  applicationId: cfnAppConfigApplication.ref,
  locationUri: 'hosted',
  name: 'cp-migration-feature-flag-app-config-profile',    
  // the properties below are optional
  description: 'Profile to store CP migration feature flags.',      
  type: 'AWS.AppConfig.FeatureFlags'
});

const configVersion = Date.now();
const base64FeatureFlagsContent = Buffer.from(JSON.stringify(
  {
    "flags": {
      "flagkey": {
        "name": "cp_migration_feature_flags"
      }
    },
    "values": {
      "flagkey": {
        "enabled": false
      }
    },
    "version": "1"
  }
)).toString('base64');

const cfnHostedConfigurationVersion = new appconfig.CfnHostedConfigurationVersion(this, 'MyCfnHostedConfigurationVersion', {
  applicationId: cfnAppConfigApplication.ref,
  configurationProfileId: cfnConfigurationProfile.ref,
  content: base64FeatureFlagsContent,
  contentType: 'application/json',
  // the properties below are optional
  description: 'Hosted configuration for CP migration feature flags.',
  latestVersionNumber: 1,
});

//Create a deployment strategy
const cfnDeploymentStrategy = new appconfig.CfnDeploymentStrategy(this, 'MyCfnDeploymentStrategy', {
  deploymentDurationInMinutes: 3,
  growthFactor: 100,
  name: 'document-vault-app-deployment-strategy',
  replicateTo: 'NONE',
  description: 'Strategy to deploy document vault configuration',
  finalBakeTimeInMinutes: 4,
  growthType: 'LINEAR'
});

const cfnDeployment = new appconfig.CfnDeployment(this, 'MyCfnDeployment', {
  applicationId: cfnAppConfigApplication.ref,
  configurationProfileId: cfnConfigurationProfile.ref,
  configurationVersion: "1",
  deploymentStrategyId: cfnDeploymentStrategy.ref,
  environmentId: cfnEnvironment.ref,

  // the properties below are optional
  description: 'Deployment of document vault configuration',
});