Don't lint files under .gitignore

[Veetaha]

Introduction

I have tflint configured in a git pre-commit hook, which you can see in this public repo. There are several problems with it

• This invocation of tflint on pre-commit hook is rather expensive because it traverses all modules in the repo including ones that didn't change during the commit. This isn't a critical problem yet, but still something that can be addressed with proper filtering which I still haven't figured out.
• This invocation of tflint processes files disabled by .gitignore which is a critical problem because it prevents me from committing my code when it finds issues in my dirty .tf files that I keep in my repo outside of source control for testing.

Proposal

The minimal fix that I'd like to propose is such that tflint ignores all files disabled by .gitignore by default.

[wata727]

That's an interesting suggestion, but it's not obvious that .gitignore should always be ignored here.
As it turns out, what you need is to ignore certain files. Please track #1929

[Veetaha]

it's not obvious that .gitignore should always be ignored here

I assume you are basing your thinking on ESLint's design, Indeed, ESLint doesn't respect the .gitignore, and in my humble opinion that is bad. I also had to work around that problem with ESlint by adding the gitgnore plugin, and I'm not very happy with that solution. I wish ESLint respected .gitignore by default with the option to opt-out from that behaviour instead.

The main reason is that in git repository setups the only files people care to lint are the ones that are checked into source control. I think this is the 99% use case actually. Having a separate tool-specific ignore config (e.g. .tflintignore) seems redundant in such case, because one would need to always keep the .gitignore and the .tflintignore (or whatever tflint config for this may be) in sync.

ESLint worked around that by providing a plugin that reads the provided .gitignore file and this way synchronizes the ESLint's view of ignores. I don't think such solution would fit tflint for several reasons:

• There is no JS ecosystem involved in tflint
• The plugin that ESLint provides requires explicit specification of the .gitignore file path. But what if I have multiple .gitignore files scattered all around my repo? I'd need to walk the directory recursively and collect all of them. Could be solved with a glob pattern support, but let's not digress too much

So I think some kind of support for .gitignore should be built in to tflint, either as an opt-in or as an opt-out (for which I prefer the latter), but the final decision is up to you.

[wata727]

In these situations, I prefer to minimize surprises as much as possible. If you have a use case where you want to inspect files that is ignored by .gitignore, you would be surprised if that files were ignored by default and didn't detect the issue you expected.

On the other hand, if TFLint detects files that you have ignored with .gitignore, it may be an inconvenience but is unlikely to be a surprise. If the inconvenience were extremely significant, there may be a decision to tolerate some surprise, but in my understanding, it is not a major problem that it would make operation difficult in reality. Please let me know if there is any misunderstanding on this point.

Given this, it may be possible to offer such a feature on an opt-in basis. However, I prefer a generic solution (e.g. glob pattern support) over a specific solution to .gitignore, as that would be more beneficial.

[Veetaha]

Yeah, opt-in is fine, as long as there is some way to ignore files outside of git

[bendrucker]

Is there prior art? Other linters that do this, aside from the notes on ESLint?

.gitignore isn't one file, you have to walk upwards to the repository root looking for matching config. TFLint doesn't currently interact with git.

[Veetaha]

Hm, it's hard to tell. Usually languages have some kind of workspace setup and manifest files that define the project structure, so linters are able to traverse the project structure seamlessly. In case of terraform I don't know of such a manifest unless tflint invents its own 🤔.

I can recall the typos CLI which traverses the directories to find typos in files. I see it has ignore-vcs that opts-in to repsecting the gitignore.

As I see it's more common for non-linting tools like deno publish or cargo publish to respect gitignore by default. I think my initial opinion was based on the experience of using these publish commands. Anyway, this is just the point of whether .gitignore is respected by default or via an opt-in. I think even if it's opt-in - it's fine. My main concern is to have at least some kind of .gitignore support or some workspace manifest format to be able to ignore files not in the source control.