kind-registry.sh

#!/bin/sh
#
# Copyright (c) 2024 Snowflake Computing Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
set -o errexit

# 1. Create registry container unless it already exists
reg_name='kind-registry'
reg_port='5001'
if [ "$(docker inspect -f '{{.State.Running}}' "${reg_name}" 2>/dev/null || true)" != 'true' ]; then
  docker run \
    -d --restart=always -p "127.0.0.1:${reg_port}:5000" --network bridge --name "${reg_name}" \
    registry:2
fi

# 2. Create kind cluster with containerd registry config dir enabled
# TODO: kind will eventually enable this by default and this patch will
# be unnecessary.
#
# See:
# https:/kubernetes-sigs/kind/issues/2875
# https:/containerd/containerd/blob/main/docs/cri/config.md#registry-configuration
# See: https:/containerd/containerd/blob/main/docs/hosts.md
cat <<EOF | kind create cluster --config=-
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
containerdConfigPatches:
- |-
  [plugins."io.containerd.grpc.v1.cri".registry]
    config_path = "/etc/containerd/certs.d"
EOF

# 3. Add the registry config to the nodes
#
# This is necessary because localhost resolves to loopback addresses that are
# network-namespace local.
# In other words: localhost in the container is not localhost on the host.
#
# We want a consistent name that works from both ends, so we tell containerd to
# alias localhost:${reg_port} to the registry container when pulling images
REGISTRY_DIR="/etc/containerd/certs.d/localhost:${reg_port}"
for node in $(kind get nodes); do
  docker exec "${node}" mkdir -p "${REGISTRY_DIR}"
  cat <<EOF | docker exec -i "${node}" cp /dev/stdin "${REGISTRY_DIR}/hosts.toml"
[host."http://${reg_name}:5000"]
EOF
done

# 4. Connect the registry to the cluster network if not already connected
# This allows kind to bootstrap the network but ensures they're on the same network
if [ "$(docker inspect -f='{{json .NetworkSettings.Networks.kind}}' "${reg_name}")" = 'null' ]; then
  docker network connect "kind" "${reg_name}"
fi

# 5. Document the local registry
# https:/kubernetes/enhancements/tree/master/keps/sig-cluster-lifecycle/generic/1755-communicating-a-local-registry
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ConfigMap
metadata:
  name: local-registry-hosting
  namespace: kube-public
data:
  localRegistryHosting.v1: |
    host: "localhost:${reg_port}"
    help: "https://kind.sigs.k8s.io/docs/user/local-registry/"
EOF