(aws-cdk): go template breaks go list

[mguterl]

aws/aws-cdk#13840 added an app template for go and the filenames break go list ./... when cdk project is embedded inside of a Go project.

Reproduction Steps

mkdir project
cd project
cdk init app --language=typescript
go mod init github.com/test/project
echo "package main\nfunc main() { return }\n" > main.go
go list ./... # fails because of template files

package github.com/test/project/node_modules/aws-cdk/lib/init-templates/v1/app/go: invalid input file name "%name%.template.go"

What did you expect to happen?

I expected go list ./... to return a list of package names.

What actually happened?

List of package name was not returned and an error was returned instead.

package github.com/test/project/node_modules/aws-cdk/lib/init-templates/v1/app/go: invalid input file name "%name%.template.go"

Environment

• CDK CLI Version: 1.96.0 (build 39f3df8)
• Framework Version: ?
• Node.js Version: v15.13.0
• OS : macOS 11.2.3
• Language (Version): all
• Go (Version): 1.16.3

Other

I think it might be possible to add an empty go.mod file into the template directory to prevent this from happening, but I'm hardly an expert in Go.

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This is 🐛 Bug Report

[MrArnoldPalmer]

we will investigate if there is an easy fix from our side. I don't know if generally this is a use case that we want to think about compatibility with. The user can put their cdk app anywhere, and node_modules can have a lot of stuff in it. Thinking about what unrelated commands that users can invoke that may conflict with any of the files within node_modules feels hard. In this case though if adding an empty go.mod or otherwise solves this seems easy enough.

[tgrobinson]

The root cause is the filename doesn't conform to the Golang filename standards by being prefixed with a %. It looks like the standards allow for . and _ prefixed filenames which may be better suited.

As a side note, I've also hit this exact error while using the go vet and go test commands on my Golang project.

[davidsteed]

This is causing us problems too with ci cd tooling and annoying errors in VSCode... If the files were .go_tempate or something that these files would not be recognised this would not be a problem. Should be an easy fix.

[mlafeldt]

I agree that an easy fix might be to rename the template from %name%.template.go to %name%.go.template.

Update: Actually, it's not that easy since the templating is generic and used for all languages.