Hot reloading does not work for subdirectories in Linux

[laurenzlong]

Environment details

• OS: Linux
• Node.js version: 7.11.5
• npm version: 3.10.10
• @google-cloud/functions-emulator version: 1.0.0-beta.4

Steps to reproduce

1. Create a functions folder where index.js is not at the root directory, but in a subdirectory such as 'lib/index.js' (this is a common pattern for users that write functions in TypeScript and then compile them to JS)
2. Emulate the function
3. Change the source code in lib/index.js
4. Observe that the worker is not closed

After taking a look at the code, it seems from this line that fs.watch is used for hotloading. This has a known limitation that recursive: true does not work on Linux (see https://nodejs.org/api/fs.html#fs_caveats). In order to work around it, what do you think about checking package.json for the main field, which indicates the file that contains the functions, and then also watching the directory that file is in? But this would still lead to problems if the main file for functions calls helper functions in other subdirectories, so it doesn't solve the issue completely. Alternatively, the emulator can crawl the entire directory first so it knows all the subdirectories to watch, but that is a lot of work. So perhaps it's worth just printing out a warning messaging when Linux is detected.

[psigen]

For what it's worth, fs.watch is somewhat known for this limitation and several third party libraries exist to deal with it.

For example, webpack has a whole high-level API watchpack which wraps a lower-level API chokidar used in several well-known frameworks to perform this exact function in a cross-platform-friendly way. Perhaps it would be useful to integrate with one of them or at least replicate their behavior?

[OrDuan]

I want to add that it's not Typescript specific. Anyone who uses Babel as well won't be able to use the hot reload.
I'm using Babel since I want to use the latest js features on my backend. To verify that the issue is related to the directory path I changed ~/.npm-global/lib/node_modules/firebase-tools/node_modules/@google-cloud/functions-emulator/src/supervisor/worker.js file from this line:

const localdir = getLocaldir(cloudfunction)

To this:

const localdir = getLocaldir(cloudfunction)+'/dist';

And the hot reload indeed works again(no reloading logging, but the function gets updated)

[Harry-Torry]

I'm developing an app with Angular 6, it's a bit hacky but straight up editing the functions/lib/index.js file works as a workaround to get functions shell to hot reload.

[sdbondi]

I added a PR here which uses chokidar and this works when I test hot reloading on one of my projects. Any help with getting this through would be appreciated 😄 I ran the tests locally before making any changes (master) and a lot of them failed/I needed to set something up. I expected circle ci to just run them when I made the PR but that didn't seem to happen. 🤷‍♂️

#223

[beeman]

Thanks a lot for landing this ❤️