Clone fails on Node: global.fetch is not a function

[strogonoff]

From a quick scan, it looks like as of this change in January 2019 http module no longer checks for global.fetch, which excludes Node environment.

I was accidentally stuck on 0.50 version, and once I updated (for the sake of fastCheckout and other niceties) I’m getting the following stack trace when cloning:

  16:00:17.707 › UnhandledRejection TypeError: global.fetch is not a function
      at http (webpack-internal:///./node_modules/isomorphic-git/dist/for-future/isomorphic-git/index.js:4931:28)
      at Function.discover (webpack-internal:///./node_modules/isomorphic-git/dist/for-future/isomorphic-git/index.js:5162:21)
      at fetchPackfile (webpack-internal:///./node_modules/isomorphic-git/dist/for-future/isomorphic-git/index.js:5975:42)
      at fetch (webpack-internal:///./node_modules/isomorphic-git/dist/for-future/isomorphic-git/index.js:5840:22)
      at Module.clone (webpack-internal:///./node_modules/isomorphic-git/dist/for-future/isomorphic-git/index.js:6321:42)

From cursory search, it seems like global.fetch isn’t supposed to be available on Node. Is reinstating the previous Node-compatible state of http’s fetching logic on the table?

[strogonoff]

I’m not sure if I’m missing something, since no one else reports such an issue.

So far I made it work by jury-rigging node-fetch’s fetch() onto global:

import fetch from 'node-fetch';
(global as any).fetch = fetch;

[billiegoose]

The node version doesn't use fetch at all... how are you importing isomorphic-git? Are you building a Node application with Webpack?

[strogonoff]

@wmhilton I’m building an Electron one, and yes, this happens on Node process side. It does a Webpack pass during build🤔

I’m not aware if Webpack supplies global.fetch. Generally speaking you’re hinting it’s likely an issue on my side and you don’t think it’s a regression in isomorphic-git’s Node support?

[billiegoose]

Yes... it's really a webpack configuration issue. Webpack is probably trying to use the module file instead of the main file, but

• the module file uses ES6 modules and is "for web" while
• the main file uses CommonJS modules and is "for node"

Which 99% of the time is right, because Webpack is usually not used on Node.js apps. You can probably make Webpack use the "right" version with an alias to dist/for-node/isomorphic-git/index.js but if you're using webpack and isomorphic-git on both the node-side and the browser-side of an Electron app, you'd need separate webpack config files....

Anyway, as you can see it's obviously a bit of a mess. And I am going to fix this in version 1.0 by pulling this troublesome bit out of the library completely and make users provide an HTTP client, just like what I already do for fs. That way the code doesn't have to try and detect whether it's running in Node or be compiled differently.

[strogonoff]

Understood, very clear. Going to take note but keep global.fetch for now, fingers crossed no other incompatibilities crop up. Thank you for awesome work!

I guess Webpack is more for browser-based code, but this mainstream Electron builder library builds on top of Webpack to transpile/bundle both Node and in-browser code. Works impressively well out of the box but that Webpack config is not for the weak of heart (or subject to deadlines) to fiddle with (which I am so I don’t, unless something’s really broken).

[davidenke]

I have the same issue as well with a quite similar setup using rollup and deskgap.
Since I could configure @rollup/plugin-node-resolve to use only the main fields and ignore the module entries, it fails for other packages during bundling. Unfortunately it can't be configured per dependency, so I have to stick to the workaround of @strogonoff as well.

@wmhilton Maybe it would help to release a meta package for node usage (e.g. isomorphic-git-node which includes just the main field: thus it can be consumed by bundlers without further configuration...?

[billiegoose]

Hi @davidenke ! See if the solution I hit upon in v1.0.0 works for you. Basically the http bit has been split off, so now you do:

import * as git from 'isomorphic-git'
import http from 'isomorphic-git/http/node'
// or
import http from 'isomorphic-git/http/web'

Full details and examples at https://isomorphic-git.org/docs/http

[billiegoose]

@strogonoff ooh! what's the name of this mainstream Electron builder library that uses Webpack to transpile and bundle both? I was actually trying to do something similar the other day from scratch using Webpack (and failed miserably).

[strogonoff]

@wmhilton I believe https://www.electron.build? That’s what we’re using!