Dockerfile - use Caddy instead of Apache2

[paragonie-scott]

We actually recommend Caddy over Apache or nginx due to its seamless LetsEncrypt integration (automatic HTTPS). Some time in the future, I'd like to play around with Docker and create a Dockerfile that installs and sets up Caddy.

If anyone wants to give this a swing before 2.0.0 is ready, I'd greatly appreciate it. Otherwise, I will eventually find time to tackle this.

[co60ca]

I might be able to do this but as you may know I have 0 experience with caddy and only experience with Apache and Nginx

[paragonie-scott]

Compare these two:

• https://github.com/paragonie/airship-docs/blob/master/en-us/01-intro/example-config/apache.conf
• https://github.com/paragonie/airship-docs/blob/master/en-us/01-intro/example-config/Caddyfile

For all intents and purposes, they're equivalent. :)

That being said, this isn't an enormous priority. Holding off until Caddy 1.0 is tagged is perfectly acceptable too.

[JoshHarmon]

@paragonie-scott Are you still interested in this given that Apache 2.4.30 (which I'd personally expect to see in Ubuntu 18.04 LTS) will have ACME support and nice ciphersuite config backported and baked into mod_md? I'm not sure the extra setup to make caddy work (and updating it) will be worth it compared to rolling with distro-packaged Apache at that point. Just figured I'd bump this to get an updated opinion since the landscape has changed significantly since this issue was created.