Add ability to specify certificate

[bdukes]

Our standard dev setup includes using local domains with generated certificates (e.g. https://client.local), so being able to pass a trusted certificate through to elm-watch improves our experience quite a bit. Let me know if there are any changes you'd like to my approach here. Thanks!

[lydell]

Hi! We were talking about being able to specify a certificate there: #46 (comment)

I was thinking the config would point to two files instead of having to paste the certificates in the config itself. What do you say?

[bdukes]

We can do that also. I was trying to get the input as close to the Node.js options as I could to avoid extra processing, but storing them as files is definitely easier for the most common scenarios. I'll try to find some time tomorrow to adjust the implementation. Thanks!

[bdukes]

@lydell I've pushed a change for the configuration to point to a file instead of containing the certificate contents. Let me know if there's anything else you need. Thanks!

[lydell]

Thanks! I’ll look into this soon. I’m going to update the docs, write tests (this repo has 100 % coverage), review error messages etc.

[lydell]

Here are some rough notes I made for myself (just to show you what the status is):

• better error messages when decoding
  • I think it makes sense to do it inside the decoders
  • another way of doing it is reading the files when doing https.createServer()
    • since that can fail anyway (see below). Not sure if easier.
• mix up key and cert -> “unexpected error” and exit. https.createServer() throws? or error event?
• simplify CertificateChoice away? Does not seem to need to be able to tell them apart
• switch to read the built in cert from files too?
• make sure that when reading, it’s relative to elm-watch.json, not cwd
• update docs mentioning “let me know if you need this”
• maybe easier to start from scratch in my own branch and use his as inspiration
• write tests

I want to do that soon, but now it’s December and other things usually get in the way.

[lydell]

I’m sorry I never got around to finishing this. I’m finally starting to get more time for open source again. The current plan for this is here: #74

If you’re still interested in this, it would be very helpful if you could comment on #74 if that approach would work for you!