Add a "Deploy to Heroku" button

[sjparkinson]

See https://devcenter.heroku.com/articles/heroku-button.

This button would live on the README.md and look something like:

Pressing it would allow anyone with a Heroku account to quickly set up a new Pa11y dashboard.

[sjparkinson]

More than happy to submit a PR for this if there is interest.

[joeyciechanowicz]

Thanks. This sounds really useful in theory.

Couple of questions:

• Can heroku sites block all traffic except for whitelisted IPs? As pa11y-dashboard is not meant as a tool that's publicly available.
• How would this work with specify a config.json or ENV variables?

[sjparkinson]

* Can heroku sites block all traffic except for whitelisted IPs?

Interesting question. Not out of the box. However I would imagine there is a Buildpack out there that we could make use of. I'll have a look around.

* How would this work with specify a `config.json` or ENV variables?

Environment variables are covered, and a configuration file I will have a look at how it works in this project first.

[sjparkinson]

Interesting question. Not out of the box. However I would imagine there is a Buildpack out there that we could make use of. I'll have a look around.

There is one robust answer to this which would be to provision the Heroku app inside a Heroku Private Space.

https://www.heroku.com/private-spaces

That would allow IP access lists to be defined and managed within Heroku, no maintenance required. There is an increased cost associated with provisioning an app in a Private Space however.

Spend Alert. Each Heroku Private Space costs $1000 in Add-on Credits/month (pro-rated to the second).

Buildpack wise, the route seems to be using an nginx based Buildpack configured with a list of IPs from a file. However the ones I've found all deal with static sites only. I'll dig into what one that supports this project would look like.

---

Configuration wise, looks like this would work just fine with the way the Heroku Deploy button supports asking for environment variables.

pa11y-dashboard/config.js

Lines 28 to 37 in c7bd2a5

	port: Number(env('PORT', '4000')),
	noindex: env('NOINDEX', 'true') === 'true',
	readonly: env('READONLY', 'false') === 'true',
	webservice: env('WEBSERVICE_URL', {
	database: env('WEBSERVICE_DATABASE', 'mongodb://localhost/pa11y-webservice'),
	host: env('WEBSERVICE_HOST', '0.0.0.0'),
	port: Number(env('WEBSERVICE_PORT', '3000')),
	cron: env('WEBSERVICE_CRON', false)
	})

https://devcenter.heroku.com/articles/app-json-schema#env