[do not merge] hack: local verification script for IPv6-only DNS - #1043
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Yuan Gao (ygao-g) wants to merge 2 commits into
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[do not merge] hack: local verification script for IPv6-only DNS#1043Yuan Gao (ygao-g) wants to merge 2 commits into
Yuan Gao (ygao-g) wants to merge 2 commits into
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CoreDNS runs dnsPolicy: Default and inherits the node's Docker-generated /etc/resolv.conf, which always names an IPv4 resolver -- unreachable from a v6-only pod, so every external lookup SERVFAILs and anything that fetches at runtime never starts. Behind that sits a second failure: the registry is wired into containerd on the node, but atelet pulls actor images from its own pod netns, where kind-registry does not resolve at all. On IPv6-only clusters CoreDNS now answers for kind-registry and forwards everything else to an IPv6 upstream, overridable with IPV6_DNS_UPSTREAM where the default is unreachable. A pod resolves external names and reaches the registry, so the control plane installs and actors boot. IPv4 and dual-stack clusters are unchanged.
Nothing exercised the IPv6-only CoreDNS rewrite except building a cluster and watching what happened, so a transform that quietly stopped matching kind's default Corefile would still have looked like a pass. The rewrite now lives in a sourceable function, and hack/verify-ipv6-dns.sh runs it against a pinned copy of that Corefile with neither Docker nor a cluster, then -- given a cluster -- asserts the shape that landed and resolves from a pod rather than the node, which is dual-stack and answers either way. Two of the offline checks are controls that must fail: an unrecognised Corefile, and re-patching an already-patched one. Reference branch stacked on the DNS fix, not a merge candidate.
Yuan Gao (ygao-g)
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Not a merge candidate — please don't merge this. It exists so anyone looking at #958 can reproduce that PR's local testing without hand-building a harness. Stacked on #958: the first commit is that PR's, only the second is new here.
hack/verify-ipv6-dns.shchecks the CoreDNS rewrite that IPv6-only kind clusters need. The offline half runs the transform against a pinned copy of kind's default Corefile and needs neither Docker nor a cluster. The live half detects the cluster's address family, asserts ipv4 and dual-stack are left alone, and probes from a pod rather than the node — the node is dual-stack and answers either way, so a node-side probe proves nothing.Two of the offline checks are controls that must fail, so a transform that silently did nothing cannot pass. Locally: 9/9 offline, 11/11 against an IPv4 cluster, 14/14 against a fresh IPv6-only one.
To make the transform testable without a cluster it moved into a sourceable function;
create-kind-cluster.shbehaviour is unchanged.🤖 Generated with Claude Code