[WIP] Experiment with option to link kmsg

THe current approach to link `/dev/kmsg` to `/dev/console` only works on
images that we build ourselves. Let's see if we can mess with the
running container and create the link at runtime / on the fly.

As this is fixed in kind already [0], we can remove that hack probably
when kind 0.5.0 is out.

Why is this linking even needed? See also [0]!

[0]: kubernetes-sigs/kind#662

Author: hoegaarden

entrypoint.sh

@@ -239,21 +239,45 @@ kind::start::fromSource() {
   # create the node image
   GOPATH="$(pwd)/go" \
     kind build node-image --image "$imageName"
-  kind::hack::inject_kmsg_linking "$imageName"
+  # kind::hack::inject_kmsg_linking "$imageName"
 
   # bring up kind
+  kind::hack::kmsg_linker "$clusterName" &
   kind create cluster --config "$KIND_CONFIG" --image "$imageName" --name "$clusterName" --loglevel "$loglevel" --retain
 
   # get the (compiled) version of kubectl
   cp ./go/src/k8s.io/kubernetes/_output/dockerized/bin/linux/amd64/kubectl ./bin/kubectl
 }
 
+kind::hack::kmsg_linker() {
+  local node clusterName sleepDur
+
+  clusterName="$1"
+  sleepDur="1s"
+
+  while sleep "$sleepDur"
+  do
+    echo '### trying to link'
+
+    node="$(kind get nodes --name "$clusterName")" || continue
+
+    docker exec "$node" sh -c \
+      'set -e; [ ! -e /dev/kmsg ] && ln -s /dev/console /dev/kmsg' \
+      || continue
+
+    break
+  done
+
+  echo "### linking worked"
+}
+
 # Start kind with the (latest) node image published by kind upstream
 kind::start::fromUpstream() {
   local clusterName="$1"
 
   log::warn "no k8s source found, using newest node image from kind upstream"
 
+  kind::hack::kmsg_linker "$clusterName" &
   kind create cluster --config "$KIND_CONFIG" --name "$clusterName" --loglevel "$loglevel" --retain
 
   # get kubectl from upstream