StaticSite: Add support for external domains

[warwickgrigg]

Enhancement. As discussed on Slack. With documentation , a new test case, and two test cases updated. I've tested this e2e for my own hostname.

In brief, for external domains omit customDomain, and include:

cfDistribution: {
  domainNames: ["www.domain.com"],
  certificate: Certificate.fromCertificateArn(this, "MyCert", certArn)
}

Then set external domain's CNAME record to the cloudfront distribution's URL.

[warwickgrigg]

@fwang Thank you for moving this forward. Is the failed check a false negative, or do I need to fix something?

[fwang]

Hey @warwickgrigg, I moved the code around a bit to rely on using the customDomain to configure external domains:

const site = new StaticSite(this, "Site", {
  path: "path/to/src",
  customDomain: {
    isExternalDomain: true,
    domainName: "domain.com",
    certificate: Certificate.fromCertificateArn(this, "MyCert", certArn),
  },
});

Behind the scene, it does exactly as what you proposed. This way, site.customDomainUrl still works.

Thanks again for working on the PR. This will go into the next release!