Show warning when usage of `npm link` causes `instanceof TerraformElement` to fail

[ansgarm]

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Description

After extracting commonly used logic (which instantiates constructs) into a separate npm package, npm link is commonly used in local development to test the library with an cdktf project.

However the way npm link works breaks the instanceof check in TerraformStack. It creates a symlink from e.g. <cdktf-project>/node_modules/<custom-library> pointing to the custom library directory. And as the custom library also has the cdktf package installed, that one is instead used for resolving dependencies to cdktf.TerraformStack (for constructs created in the custom library code). This causes the check in TerraformStack.allocateLogicalId to fail and produces the following error: TypeError: node.tryGetContext is not a function.

Instead of this hard to debug error, we could e.g. probe the passed argument and check whether it probably is in fact a TerraformStack and print a more useful warning message (e.g. recommending yalc – see workaround section).

We could also get rid of instanceof for the check but that could only defer the underlying issue to a later (possibly even harder to debug) place in the code.

Workaround for the issue caused by npm link

Using yalc to link packages for local development solves the issue as it works differently.

References

• https://github.com/hashicorp/terraform-cdk/blob/0732e9f5bbf2e85f7eb2cd131855fe6bf0e8b641/packages/cdktf/lib/terraform-stack.ts#L118-L121

[DanielMSchmidt]

We should check if using symbols solves this problem, e.g. like we do in https://github.com/hashicorp/terraform-cdk/blob/main/packages/cdktf/lib/terraform-stack.ts#L43-L45

[cprice404]

This has been biting me pretty regularly, and it's not limited to the node instanceof check; I tried hacking the js source for that file inside of my node_modules directory to get past this error, and I hit another one on this line:

https://github.com/hashicorp/terraform-cdk/blob/abe8435e74de96cc1d969fb257a0f9123702a63c/packages/cdktf/lib/validations/validate-provider-presence.ts#L22

In general those instanceof checks do not play nicely with local library dev and it would be super helpful if there was a different way to implement the checks.

[cloneluke]

I got this error when I didnt have a required/used provider installed, FYI

[amarflybot]

I got this error when I used Oracle OCI non-prebuilt Provider.

[mbazalik]

@ansgarm - are you planning to release that as a prerelease anytime soon? (We have been trying to run our config with 0.14.0-pre.5 with no luck so far)

[ansgarm]

Hey @mbazalik, we can merge that PR soon – we needed to wait making breaking changes because of the guarantee we gave for 0.12 prebuilt providers working with 0.13 (and patch releases of 0.13) 😇

[ansgarm]

@mbazalik fyi: the PR was just merged 👍

[jlsalmon]

I got this error when I was using cdktf-cli v0.13.2, but one of my dependencies was accidentally pulling in v0.12.3 inside node_modules.

[ansgarm]

Closed via https://github.com/hashicorp/terraform-cdk/pull/2125

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