IPv6 on GitHub-hosted runners

[BrightRan]

This issue is transferred from here.

In this ticket, the user is trying to reach the IPv6 address of Google by running the command "curl -6 https://www.google.com" on the GitHub-hosted Ubuntu runner, but it always failed to connect and returned the message "Couldn't connect to server".
The command "curl https://www.google.com" or "curl -4 https://www.google.com" can work fine to reach the IPv4 address.

I also tested directly ping the IPv6 address of Google via the command "ping6 ipv6.google.com", it also failed to connect and returned the message "connect: Network is unreachable".

To check whether the current Linux kernel supports IPv6 via the command,

[ -f /proc/net/if_inet6 ] && echo 'IPv6 ready system!' || echo 'No IPv6 support found! Compile the kernel!!'

It returns "IPv6 ready system!", looks like IPv6 is supported.
Then to check whether the IPv6 module has loaded,

lsmod | grep -qw ipv6 && echo "IPv6 kernel driver loaded and configured." || echo "IPv6 not configured and/or driver loaded on the system."

It returns "IPv6 not configured and/or driver loaded on the system.", looks like the IPv6 module is not loaded.
Load the IPv6 module and check again.

modprobe ipv6
lsmod | grep -qw ipv6 && echo "IPv6 kernel driver loaded and configured." || echo "IPv6 not configured and/or driver loaded on the system."

The returned result still shows that the IPv6 module is not loaded. Looks like this should be the reason for failed to reach the IPv6 address.

Why it can't load the IPv6 module on the GitHub-hosted runner? Whether this is an expected behavior for some limitations set on the hosted runners?

[miketimofeev]

@BrightRan looks like the images itself are ok.
@alepauly do we have ipv6 configured on the environment side?

[airtower-luna]

According to the Docker documentation the images would still need to enable IPv6 for Docker containers, even if the VMs start to support it.

[alepauly]

Unfortunately we can't support this at this time due to infrastructure constraints.

[lzhecheng]

Unfortunately we can't support this at this time due to infrastructure constraints.

Is it in the roadmap? I found no opening issues on IPv6 support. Thanks.

[miyurusankalpa]

GitHub IP address list now has IPv6 address for GitHub Actions.
https://api.github.com/meta

[oscartbeaumont]

As of a week ago, I could not get IPv6 working in GitHub Actions but let's hope them listing those address's means they are about to release support for it.

[pavelkim]

Tested today.
Under both ubuntu-latest and ubuntu-20.04:

curl -vv --ipv6 "[2607:f8b0:4002:c03::93]:80"

* Rebuilt URL to: [2607:f8b0:4002:c03::93]:80/
*   Trying 2607:f8b0:4002:c03::93...
* TCP_NODELAY set
* Immediate connect fail for 2607:f8b0:4002:c03::93: Network is unreachable
* Closing connection 0
curl: (7) Couldn't connect to server

ip route sh

default via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.4 metric 100 
10.1.0.0/16 dev eth0 proto kernel scope link src 10.1.0.4 
168.63.129.16 via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.4 metric 100 
169.254.169.254 via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.4 metric 100 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown 

ip addr sh

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0d:3a:c6:7b:12 brd ff:ff:ff:ff:ff:ff
    inet 10.1.0.4/16 brd 10.1.255.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20d:3aff:fec6:7b12/64 scope link 
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:79:06:ee:ce brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever

No IPv6 routes so far.

[undergroundwires]

Here's my workaround (open-source and documented) that I hope that can help you too:

• privacy.sexy | force-ipv4: GitHub action to use for GitHub workflows.
• privacy.sexy | force-ipv4.sh.: Script for general use.

After days of research and trial/error, this is how I got this working:

1. Create a script called force-ipv4.sh, that configures system to prefer IPv4 over IPv6, call it to configure the machine. It was not easy to find a reliable cross-platform solution and I went Cloudflare WARP for DNS resolution along with some system configurations.
2. To easily use the script in GitHub workflows, create GitHub action called force-ipv4 and call it in GitHub runners.
3. Fixes the IPv6 request issues, and you can happily run e.g. fetch API from Node.

Related commit introducing this fix: undergroundwires/privacy.sexy@52fadcd