Code change:
<!-- This form is for bug reports and feature requests ONLY! If you're looking for help check and the . --Is this a BUG REPORT or FEATURE REQUEST?: BUG REPORT What happened: When using IPv6 addresses, the kubelet passes the address to client-go, which does not correctly format the address for use in API requests. For example: Failed to list v1.Pod: Get https://2001:129::136:6443/api/v1/pods?fieldSelector=spec.nodeName%3Dnode136&resourceVersi on=0: dial tcp: too many colons in address 2001:129::136:6443 What you expected to happen: The URI should have https://[2001:129::136]:6443, so that SplitHostPort() will correctly be able to separate the host and port components. How to reproduce it (as minimally and precisely as possible): Create cluster using IPv6 address (e.g. kubeadm init --apiserver-advertise-address=2001:129::136). When the kubelet starts up, it'll log this error. Anything else we need to know?: This is being handled as part of effort to support IPv6 in Kubernetes. Was found by a co-worker, I'll work on a commit to fix. Environment: Kubernetes version (use ): Using latest, via KubeAdm Cloud provider or hardware configuration*: bare-metal OS (e.g. from /etc/os-release): Ubuntu 16.04 Kernel (e.g. ): 4.4.0-81-generic Install tools: Using KubeAdm Others:
/area client-libraries /area kubelet /area ipv6
/assign
The point of failure is here: SplitHostPort will accept IPv4 and IPv6 addresses, but the latter must have square brackets around the IPv6 address.
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/sig api-machinery because client-go
Should we open this on the repository?
I see in the client-go repo read me that it states: Does that confirm that I should do a PR here?
One thing that I was wonder, was whether or not the hostname/address provided in the call to getListener, has been validated. If so, and it can only be a hostname, IPv4, or IPv6 address as a string, we could just check if there is a ":" in the name to determine IPv6. Otherwise, I could use net.ParseIP(), and net.To4() to determine if IPv6. I'll start working with the latter assumption, but please let me know, if the former could be used.
Also, I'm making the assumption that we'd want to make client-go be able to handle IPv6 addresses, rather than having each user of client-go (e.g. kubelet) from ensuring that the IP address is of the right form. IOW, have client-go add the needed [] around IPv6 addresses, rather than have kubelet do that. My thought is that there may be cases where we want just the IP address and not the modified IP. Does that sound OK?

Related discussion:
text: ExpectedListenerAddress: "127.0.0.1", }, { <del> Hostname:                "[::1]", </del> <ins> Hostname:                "::1", </ins> Protocol:                "tcp6", ShouldRaiseError:        false, ExpectedListenerAddress: "::1", }, { <del> Hostname:         "[::1]", </del> <ins> Hostname:         "::1", </ins> Protocol:         "tcp4", ShouldRaiseError: true, },