KinD Dockerfile seems broken

[mattmoor]

I was trying to add a periodic build of this via actions, which I could use to test with KinD in CI and it seems to be failing with:

update-alternatives: using /usr/sbin/iptables-legacy to provide /usr/sbin/iptables (iptables) in auto mode
update-alternatives: using /usr/sbin/ip6tables-legacy to provide /usr/sbin/ip6tables (ip6tables) in auto mode
update-alternatives: using /usr/sbin/iptables-nft to provide /usr/sbin/iptables (iptables) in auto mode
update-alternatives: using /usr/sbin/ip6tables-nft to provide /usr/sbin/ip6tables (ip6tables) in auto mode
update-alternatives: using /usr/sbin/arptables-nft to provide /usr/sbin/arptables (arptables) in auto mode
update-alternatives: using /usr/sbin/ebtables-nft to provide /usr/sbin/ebtables (ebtables) in auto mode
Processing triggers for libc-bin (2.28-10) ...
update-alternatives: using /usr/sbin/iptables-legacy to provide /usr/sbin/iptables (iptables) in manual mode

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now
The command '/bin/sh -c apt-get update && apt-get install -y iptables &&     update-alternatives --set iptables /usr/sbin/iptables-legacy &&     mkdir -p /opt/cni/bin &&     curl -Ls https://github.com/containernetworking/plugins/releases/download/${CNI_PLUGINS_VERSION}/cni-plugins-linux-${TARGETARCH}-${CNI_PLUGINS_VERSION}.tgz | tar xzv -C /opt/cni/bin' returned a non-zero code: 2

You can see the actions run here: https://github.com/mattmoor/mink/runs/1605720393?check_suite_focus=true#step:5:1421

[mattmoor]

I see, you added args without defaults 🤔

a7cd58a#diff-dd2c0eb6ea5cfc6c4bd4eac30934e2d5746747af48fef6da689e85b752f39557

[AkihiroSuda]

Please try export DOCKER_BUILDKIT=1

TARGETARCH might not be defined on legacy builder.

[mattmoor]

It is not, I added: --build-arg TARGETARCH=amd64

[mattmoor]

Seems past that failure now, so IDK if you want to close this, or update any docs / defaults so this just works again.