IPv6 addresses are broken due to buggy HTTP proxy check

[ismacasti]

Is this a BUG REPORT or FEATURE REQUEST?

BUG REPORT

Versions

kubeadm version (use kubeadm version):
kubeadm version: &version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.3", GitCommit:"2d3c76f9091b6bec110a5e63777c332469e0cba2", GitTreeState:"clean", BuildDate:"2019-08-20T11:44:48Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/amd64"}

Environment:

• Kubernetes version (use kubectl version):
  Client Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.3", GitCommit:"2d3c76f9091b6bec110a5e63777c332469e0cba2", GitTreeState:"clean", BuildDate:"2019-08-20T11:45:27Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/amd64"}
  Server Version: version.Info{Major:"1", Minor:"15", GitVersion:"v1.15.3", GitCommit:"2d3c76f9091b6bec110a5e63777c332469e0cba2", GitTreeState:"clean", BuildDate:"2019-08-20T11:40:58Z", GoVersion:"go1.12.9", Compiler:"gc", Platform:"linux/amd64"}
• Cloud provider or hardware configuration:
  OpenStack
• OS (e.g. from /etc/os-release):
  PRETTY_NAME="SUSE Linux Enterprise Server 15 SP1"
• Kernel (e.g. uname -a):
  Linux master-0-n25-eccd-ci-02-jenkins 4.12.14-197.15-default kubeadm join on slave node fails preflight checks #1 SMP Thu Aug 1 12:18:13 UTC 2019 (8a1385f) x86_64 x86_64 x86_64 GNU/Linux
• Others:

What happened?

kubeadm init fails on IPv6 clusters when the machine IPv6 address ends on an address that contains letters.
2001:db8::1 --> OK
2001:db8::f --> FAIL
The error message is:
[ERROR HTTPProxy]: parse https://2001:db8::f: invalid port ":f"

What you expected to happen?

kubeadm to come up and configure the control plane.

How to reproduce it (as minimally and precisely as possible)?

kubeadm init on a machine with an IPv6 address that ends in letters

Anything else we need to know?

This seems to be a parse error in Golang, reproducible here:
https://play.golang.org/p/T9lvfcRBW1c

[neolit123]

This seems to be a parse error in Golang, reproducible here:
https://play.golang.org/p/T9lvfcRBW1c

hi, as you pointed out this is something in golang and not kubeadm.
to distinguish ipv6 port from address please use [ ... ]:..
and let me know if it works.

example:
https://play.golang.org/p/PbPud__MTFU

/triage support

[ismacasti]

Hi, that's not possible. Setting the node IP addresses in kubeadm.conf with brackets does not work, kubeadm complaints that it expects an IPv4 or IPv6 address.

[ismacasti]

Workaround: add --ignore-preflight-errors=HTTPProxy to kubeadm

[kad]

I'll have a look at this. I think it is trivial to fix.
/assign

[rosti]

Everywhere else we seem to be using net.JoinHostPort which does the proper bracket wrapping for IPv6 addresses. However, in this check in particular, net.JoinHostPort is not used (because we don't take the port number into account, the check does not require that).
Hence, we need to check if the address is IPv6 and bracket wrap it if it is and it's not wrapped already.

[ismacasti]

Thanks a lot!!