Add Node DNS as a Webpack mock - PR Linked

[Downchuck]

Presently CRA works quite well for isomorphic web applications: I've only hit one strong issue -- node built-ins as required by submodules. So when I hit: "Module not found: Can't resolve 'dns'" with my yarn start, I was unable to work around it, short of manually editing a node module (a pain).

Several libraries have worked to remove dns from their require statements. This issue bubbled from node-postgres, which has a direct require('dns') statement that I've had to comment out. With that done, life just works, for a rather large and complicated, multiple component application.

Unfortunately, I've not found another route.

I attempted to add a stub for dns in package.json, but as "pg" is included from the sub-project, I was unable to work-around the issue. As I'm using serve and build, not test, I don't have Jest mocks to fall back on.

I am doing all I can not to run an eject, as I'd like to stay simple and with the mainline of CRA.

So with all of that said, I'm looking/asking if there is a method for accommodating the peculiar use case of dependencies that have calls to node built-ins, such that they do not break the build.

Obviously I am not asking that we actually make them work -- once the build runs I have no issue mocking those libraries to take different routes.

[Downchuck]

Here's an example of a work-around that didn't work for me, in node-postgres, because node-postgres itself is included from a submodule: skeggse/isemail#26 (comment)

[heyimalex]

Maybe we should just add dns to the stubbed node builtins here.

[Downchuck]

@heyimalex That seems likely to fix the issue I'm hitting. My active thread for node-postgres brianc/node-postgres#1822 is not likely to result in a change in their codebase.

It's also a little strange for them to need to move a require statement down into a try catch block. Once the stub is in, I believe I can easily just mock any calls that libraries are using. I'll go ahead and submit a PR.

[Downchuck]

PR seems to have stalled on some unrelated Travis CI things.

[Downchuck]

@mrmckeb I'm getting stuck on the build - is this directly related to mocking DNS or just a temporary issue with the CI?