IPv6 support

[tambry]

The website is inaccessible over IPv6 for people like me.

[stefwalter]

Hmmm, good point.

It looks like we need to setup an AAAA record for cockpit-project.org. I believe Github now supports IPv6. I'm not sure what the AAAA should be though:

$ host cockpit-project.org
cockpit-project.org has address 192.30.252.154
cockpit-project.org has address 192.30.252.153
$ host cockpit-project.github.io
cockpit-project.github.io is an alias for sni.github.map.fastly.net.
sni.github.map.fastly.net has address 151.101.37.147
sni.github.map.fastly.net has IPv6 address 2a04:4e42:9::403

I do see this, but it doesn't provide the necessary information:

isaacs/github#354

@sgallagher Do you know of any other domain pointed at GitHub that has added correct AAAA records?

[tambry]

GitHub Pages is the only part of GitHub, which has IPv6 support. Unfortunately no IPv6 support is available for custom domains — officially. After a bit of digging, one can reach a custom GitHub Pages domain over IPv6 using 2A04:4E42::403 (this is actually an IP belonging to the CDN GitHub uses).

This can be confirmed easily with curl:
curl "http://[2A04:4E42::403]" --header "Host:cockpit-project.org"

[tambry]

An alternative method would be to use Cloudflare's free plan as a proxy server, which in addition to IPv6 support would provide HTTPS support.

[stefwalter]

@sgallagher Is an AAAA record like this something we could do for cockpit-project.org?

. IN AAAA 2A04:4E42:2E::403

[sgallagher]

Just got back from vacation.

@stefwalter Is the syntax in #139 (comment) exact? If so, I can push that out right now.

I'm not familiar with the . in AAAA format. What does the leading dot indicate?

[sgallagher]

bump
@stefwalter can you comment?

[tambry]

I've done a bit more research into this and think there's a better approach than adding a specific AAAA record.

GitHub Pages uses Fastly CDN, which in turn uses GeoDNS to return the closest IP. This can be confirmed by querying DNS for cockpit-project.github.io from different physical locations. One can also note that pinging the IPs queried in this ways will always result in lower latencies than those in this help article, which cockpit-project.org currently uses.

To achieve the exact same better behaviour for a custom domain, adding a CNAME record, which points to cockpit-project.github.io should work. It makes sense to do this for both A and AAAA queries due to the aforementioned benefits. In fact, this is described in this help article.

[stefwalter]

@sgallagher Sorry for missing your response. I was catching up from vacation too :)

The solution that @tambry talks about seems to make more sense. What do you think? @sgallagher I believe the record would look like this. It would need to replace the current A record:

. IN CNAME cockpit-project.github.io.

[sgallagher]

@stefwalter OK, I just made the following change to our DNS records, which should make their way out over the next 24 hours:

-@           IN  A   192.30.252.153
-@           IN  A   192.30.252.154
+. IN CNAME cockpit-project.github.io.

[martinpitt]

It seems this broke DNS completely. dig @ns1.redhat.com. cockpit-project.org now does not have any results. curl http://cockpit-project.org fails with "Could not resolve host: cockpit-project.org" from four different places, and so does firefox.

[tambry]

I can't see a CNAME record from the Google DNS query tool nor from my own computer.
@sgallagher Try making sure the CNAME record was added correctly?

[sgallagher]

I just reverted the change completely. The previous records should propagate out soon.

[tambry]

The problem probably happened because CNAME records can't be added to a root domain.

One of the following should actually work:

1. If the DNS server you're using supports CNAME flattening (aka ANAME records), then add such a record to the root domain, which points to cockpit-project.github.io.
2. Move the GitHub Pages site to a www subdomain and add the CNAME record to that subdomain.

[Neustradamus]

To follow this ticket.