aws-cdk: cli: cdk synth doesn't output yaml when having dependency stacks

❓ General Issue

I have a LambdaStack depending on NetworkStack’s vpc. There is the code

LambdaStack

import cdk = require('@aws-cdk/core');
import lambda = require('@aws-cdk/aws-lambda');
import iam = require('@aws-cdk/aws-iam');
import vpc = require('@aws-cdk/aws-ec2')

interface LambdaStackProps extends cdk.StackProps {
  vpc: vpc.Vpc
}

export class LambdaStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props: LambdaStackProps) {
    super(scope, id, props);
    // define lambdas by using props.vpc
  }
}

NetworkStack

import cdk = require('@aws-cdk/core');
import ec2 = require("@aws-cdk/aws-ec2");
import iam = require("@aws-cdk/aws-iam");


interface NetworkStackProps extends cdk.StackProps { }

export class NetworkStack extends cdk.Stack {
  public readonly vpc: ec2.Vpc;
  constructor(scope: cdk.Construct, id: string, prop: NetworkStackProps) {
    super(scope, id, prop);
    this.vpc = new ec2.Vpc(some code here);
  }
}

app

const networkStack = new NetworkStack(app, 'network-stack-dev', { env: UsEast1Env });
const lambdaStack = new LambdaStack(app, 'lambda-stack-dev', { 
  env: UsEast1Env,
  vpc: networkStack.vpc
});

I tried to generate yaml file for LambdaStack by executing

cdk synth lambda-stack-dev > template.yaml

Then I got

Including dependency stacks: network-stack-dev
Successfully synthesized to /Users/whao/Developer/serverless-dev/cdk.out
Supply a stack name (network-stack-dev, lambda-stack-dev) to display its template.

I tried cdk synth network-stack-dev lambda-stack-dev but it gave the same output. I am kinda confused with what Supply a stack name (network-stack-dev, lambda-stack-dev) to display its template. means

I have read issue #3259 but I didn’t find it helpful. Forgive me if I am asking stupid questions.

Environment

CDK CLI Version: 1.4.0 (build 175471f)
Module Version: N/A
OS: macOS 10.14.6
Language: TypeScript

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 28
Comments: 20 (6 by maintainers)

Commits related to this issue

fix(cli) cdk synth doesn't output yaml for explicitly specified stacks that have dependency stacks fixes #3721 — committed to madeline-k/aws-cdk by madeline-k 3 years ago
fix(cli): cdk synth doesn't output yaml for stacks with dependency stacks (#14805) * fix(cli) cdk synth doesn't output yaml for explicitly specified stacks that have dependency stacks fixes #3721 ... — committed to aws/aws-cdk by madeline-k 3 years ago
fix(cli): cdk synth doesn't output yaml for stacks with dependency stacks (#14805) * fix(cli) cdk synth doesn't output yaml for explicitly specified stacks that have dependency stacks fixes #3721 ... — committed to hollanddd/aws-cdk by madeline-k 3 years ago

Most upvoted comments

@sacag I was struggling with this myself and I found that if I added the --exclusively, -e flag to the synth command, I could get it to generate the YAML for the dependent stack. Hope that helps.

+28

ctaylor-osv on Aug 12, 2020

bumping this up as a p1 to prioritize a fix

shivlaks on May 19, 2020

We’re still seeing this issue in 1.19.0 - what’s the likelihood of it being picked up? It’d be great to be able to synth stacks without relying on cdk.out and having to convert the generated json into yaml for readability

EDIT: After looking through the code in aws-cdk, it appears that what’s happening is upstream stacks are being synthesized too, even if you specify a particular stack. Adding the -e flag sets exclusively to true, and only synthesizes the specified stack. It’s not clear from the docs that the list of stacks to synthesize is also the list of stacks it tries to print, so if there’s a dependency, it’ll try to synthesize those also, and fail to print to stdout because there are more than one.

I’d suggest updating the printed text on packages/aws-cdk/bin/cdk.ts:334 to suggest that -e might help if there are dependencies.

dabarrell on Jan 8, 2020

makr11 on Jan 7, 2021

put the hack code at the end of app.ts can generate all yaml files in cdk.out:


import {serializeStructure} from "aws-cdk/lib/serialize";
import { ISynthesisSession, Stack} from "@aws-cdk/core";
import * as path from "path";

...

const old = Stack.prototype._synthesizeTemplate;
const nw = function (this: Stack, session: ISynthesisSession) {
    old.apply(this, [session])

    const builder = session.assembly;
    const template = this._toCloudFormation();
    const outPath = path.join(builder.outdir, this.templateFile + ".yaml");
    fs.writeFileSync(outPath, serializeStructure(template, false));
}

Stack.prototype._synthesizeTemplate = nw

gyang-vonage on May 19, 2021

Hello @nija-at - do you know if there is a solution to generate YAML for dependent stacks?

sacag on Feb 11, 2020

@dabarrell - thanks for the suggestion! We’ll change for this to explain this better.

Also, we’re fairly good at reviewing and accepting pull requests, in case you’d like to help us out.

nija-at on Jan 8, 2020

As a workaround, both the synthesized stack is present in the cdk.out folder in JSON format. That should unblock anyone who wants to find the synthesized stacks.

@jayrmotta - the issue you’re pointing out is being tracked in #3705. This one is about cdk synth not producing the expected synthesized yaml.

nija-at on Aug 23, 2019