feat(mailer): add support for sending SMS messages

[philbooth]

Related to mozilla/fxa-auth-server#1628.

• Define the API.
• Include SMS messages in the auth mailer templates for l10n.
• Implement phone number validation.
• Unit tests.
• Fix Invalid Text Message error from Nexmo.
• Test out sending actual messages to the UK, the USA and Canada.
• Export the sms interface for direct calling.
• Include the proper install link.
• Include the finalised message text.
• Include the finalised sender ids.

/cc @shane-tomlinson @vbudhram

[shane-tomlinson]

What're these?

[philbooth]

What're these?

Virtual numbers that I'm using for testing.

As per the documentation, legal values for the sender id depend on the region we're sending to. For the UK we can use an alphanumeric string up to 11 characters long, hence Firefox. For the USA it has to be a phone number, so I just plugged in the virtual phone number I'm using for USA testing, for now. For Canada, we should be able to use the short code that was already associated with our Nexmo account, according to the docs. However, in practice I found this got rejected by the network provider, so I've switched to the virtual number I'm using for testing there too.

For all of this, note the last item in the issue check-list: Include the finalised sender ids. It's one of the things we need to pin down before this PR can be merged.

[shane-tomlinson]

Ya, we need a real link. @davismtl - what adjust link should we point people at? Should we run it through the moz.la shortener?

[davismtl]

Hey, I recommend looking at this document: https://docs.google.com/spreadsheets/d/151_fWwEPxmPN_AbHCp-sqAkshDCLaABRrVaowxoFS10/edit#gid=0

This is our Adjust master tracker for owned channels. You should both have edit access now.

There are some rows with FxA in there. You will see the nomenclature of the URLs.

I recommend shortner too since it would be too long in SMS.

[davismtl]

And here are the deeplinking parameters too for the next phases: https://docs.adjust.com/en/deeplinking/

[shane-tomlinson]

👍 I'm excited to see this come together @philbooth!

[shane-tomlinson]

I'm assuming this will also be done on the auth server.

[philbooth]

Why?

[philbooth]

Or did you mean that you assume some validation will be done on the auth server, rather than explicitly this validation?

I do have rudimentary validation at the API level, yes. /^\+[1-9]\d{1,14}$/ is the regex, if you're interested.

[shane-tomlinson]

Or did you mean that you assume some validation will be done on the auth server,

Yes.

[shane-tomlinson]

This error will be returned to the auth-server I'm guessing. What does the auth-server do with it? Does the auth-server convert errors to the standardized format where each error gets its own errno?

[philbooth]

The auth server work isn't finished yet. When it is, it will return an appropriate error.

[shane-tomlinson]

This may be pre-mature, any value in passing in the sendSms function so that we can swap out providers if need be, e.g., if we decide to use Basket or Amazon SNS instead of Nexmo? Basket may duplicate a lot of the functionality here, I'm not sure how it works.

[philbooth]

I don't see the point in doing it now. It's a possibility I'm aware of and that we spoke about, but writing code to handle multiple SMS APIs feels like wasted cycles at this stage. I don't foresee it being difficult to do, if/when we need it. None of the implementation/provider details leak outside of this module.

[shane-tomlinson]

What's this file for? Necessary to load the templates?

[philbooth]

The generic template code assumes HTML versions of every template. Obviously that makes no sense for SMS, so I made it a symlink, which is what this is. But it doesn't need to be a symlink, it could be an empty file, or anything really.

Or I could add some conditional logic to the template code that ignores HTML files for sms.* templates, but that felt a bit like unnecessary complexity when I thought about it before.