Example CDKTF file

cdktf.ts

import { Construct } from "constructs";
import { App, RemoteBackend, TerraformStack, TerraformHclModule, TerraformOutput } from "cdktf";
import { AwsProvider } from "@cdktf/provider-aws";

// These variables are hardcoded here for brevity but the values could be stored and fetched from anywhere.
const DEPLOYMENT_TARGETS = {
  // region : aws account id
  "ap-northeast-1": "582318560864",
  "ap-northeast-2": "600734575887",
  "ap-south-1": "718504428378",
  "ap-southeast-1": "114774131450",
  "ca-central-1": "985666609251",
  "eu-central-1": "054676820928",
  "eu-west-1": "156460612806",
  "eu-west-2": "652711504416",
  "eu-west-3": "009996457667",
  "sa-east-1": "507241528517",
  "us-east-1": "127311923021",
  "us-east-2": "033677994240",
  "us-west-1": "027434742980",
  "us-west-2": "797873946194",
};

const MODULE_VERSIONS = {
  default: "1.0.0",
  regionalOverride: {
    "eu-west-2": "2.0.0",
  },
};

/**
 * Utility function, create aws providers for all regions.
 */
function createAllProviders(scope: Construct, deploymentTargets: Record<string, string>) {
  const allProviders: Record<string, AwsProvider> = {};

  for (const [region, accountId] of Object.entries(deploymentTargets)) {
    allProviders[region] = new AwsProvider(scope, `a${accountId}-${region}`, {
      alias: `a${accountId}-${region}`,
      region,
      assumeRole: {
        roleArn: `arn:aws:iam::${accountId}:role/IaC`,
      },
      defaultTags: {
        tags: {
          System: "core",
        },
      },
    });
  }

  return allProviders;
}

interface StackConfig {
  deploymentTargets: Record<string, string>;
  moduleVersions: {
    default: string;
    regionalOverride: Record<string, string | undefined>;
  };
}

class MyCdkStack extends TerraformStack {
  constructor(scope: Construct, stackName: string, config: StackConfig) {
    super(scope, stackName);

    // Create all the provider configurations
    const allProviders = createAllProviders(this, config.deploymentTargets);

    // Create module resources for all generated providers.
    const allModules: Record<string, TerraformHclModule> = {};
    for (const [region, provider] of Object.entries(allProviders)) {
      allModules[region] = new TerraformHclModule(this, `normal-hcl-module-${region}`, {
        source: "terraform_registry",
        variables: {
            module_input_var: "a value"
        },
        // Overide module version based on region.
        version: config.moduleVersions.regionalOverride?.[region] || config.moduleVersions.default,
        providers: [provider],
      });
    }

    // Bubble up module outputs to top level
    for (const [region, module] of Object.entries(allModules)) {
      new TerraformOutput(this, `hcl-module-${region}-output`, {
        value: module.get("module_output_name"),
        description: `Output for region ${region}`,
        staticId: true,
      });
    }
  }
}

const app = new App();
const myCdkStack = new MyCdkStack(app, "stack", {
  deploymentTargets: DEPLOYMENT_TARGETS,
  moduleVersions: MODULE_VERSIONS,
});

new RemoteBackend(myCdkStack, {
  organization: "org",
  hostname: "hostname",
  workspaces: {
    name: "cdktf",
  },
});

app.synth();