Allow providers to be defined globally on the app, rather than in each stack

[acdoussan]

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Description

Currently, the providers have to be defined directly on each stack. My provider configuration does not change between stacks. It would be nice if the cdk implementation walked up the object chain and used the first provider definition it finds, so I can define it in a single place.

Example (this doesn't work):

main.ts

import { HomelabApp } from 'src/app';

const app = new HomelabApp();
app.synth();

src/app.ts

import { App, AppOptions } from "cdktf";
import { ProxmoxProvider } from 'gen/providers/proxmox/provider';
import { K8sStack } from './k8s';

export class HomelabApp extends App {
  public readonly proxmoxProvider: ProxmoxProvider;
  public readonly k8sStack: K8sStack;

  constructor(options?: AppOptions) {
    super(options);

    this.proxmoxProvider = new ProxmoxProvider(this, 'proxmox-provider', {
      pmApiUrl: <redacted>,
      pmUser: <redacted>,
      pmPassword: <redacted>,
    });

    this.k8sStack = new K8sStack(this, "k8s");
  }
}

src/k8s.ts

import { Construct } from "constructs";
import { TerraformStack } from "cdktf";
import { Lxc } from "gen/providers/proxmox/lxc";

export class K8sStack extends TerraformStack {
  public readonly test: Lxc;

  constructor(scope: Construct, id: string) {
    super(scope, id);

    this.test = new Lxc(this, 'lxc-test', {
      <redacted config, not relevant>
    });
  }
}

tsconfig.json

{
  "compilerOptions": {
    "paths": {
      "src/*": ["./src/*"],
      "gen/*": ["./.gen/*"]
    },
    "alwaysStrict": true,
    "charset": "utf8",
    "declaration": true,
    "experimentalDecorators": true,
    "inlineSourceMap": true,
    "inlineSources": true,
    "lib": ["es2018"],
    "module": "CommonJS",
    "noEmitOnError": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitAny": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "resolveJsonModule": true,
    "strict": true,
    "strictNullChecks": true,
    "strictPropertyInitialization": true,
    "stripInternal": true,
    "target": "ES2018",
    "incremental": true,
    "skipLibCheck": true
  },
  "ts-node": {
    "require": ["tsconfig-paths/register"]
  },
  "include": ["**/*.ts"],
  "exclude": ["node_modules", "cdktf.out"]
}

Error I get when running npm run synth -- --json

[2023-01-14T15:43:03.640] [ERROR] default - Error: Validation failed with the following errors:
  [k8s] Found resources without a matching provider construct. Please make sure to add provider constructs [e.g. new RandomProvider(...)] to your stack 'k8s' for the following providers: proxmox
    at K8sStack.runAllValidations (/Users/acdoussan/git/homelab/terraform/node_modules/cdktf/lib/terraform-stack.ts:342:13)
    at StackSynthesizer.synthesize (/Users/acdoussan/git/homelab/terraform/node_modules/cdktf/lib/synthesize/synthesizer.ts:30:18)
    at /Users/acdoussan/git/homelab/terraform/node_modules/cdktf/lib/app.ts:129:49
    at Array.forEach (<anonymous>)
    at HomelabApp.synth (/Users/acdoussan/git/homelab/terraform/node_modules/cdktf/lib/app.ts:129:12)
    at Object.<anonymous> (/Users/acdoussan/git/homelab/terraform/main.ts:4:5)
    at Module._compile (node:internal/modules/cjs/loader:1105:14)
    at Module.m._compile (/Users/acdoussan/git/homelab/terraform/node_modules/ts-node/src/index.ts:1618:23)
    at Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
    at Object.require.extensions.<computed> [as .ts] (/Users/acdoussan/git/homelab/terraform/node_modules/ts-node/src/in
ERROR: cdktf encountered an error while synthesizing

References

[jsteinich]

A sort of workaround could be to create a function that creates the provider so that the configuration is one spot and you just need to call it from each stack.