From 6f900420bf3f3417c8a90fb985b18db125d60bf8 Mon Sep 17 00:00:00 2001
From: Mathieu Tortuyaux <mtortuyaux@microsoft.com>
Date: Thu, 13 Jul 2023 11:20:12 +0200
Subject: [PATCH] bakery: add kubernetes sysext helper

Signed-off-by: Mathieu Tortuyaux <mtortuyaux@microsoft.com>
---
 create_kubernetes_sysext.sh | 96 +++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100755 create_kubernetes_sysext.sh

diff --git a/create_kubernetes_sysext.sh b/create_kubernetes_sysext.sh
new file mode 100755
index 0000000..b9b943e
--- /dev/null
+++ b/create_kubernetes_sysext.sh
@@ -0,0 +1,96 @@
+#!/bin/bash
+set -euo pipefail
+
+export ARCH="${ARCH-amd64}"
+SCRIPTFOLDER="$(dirname "$(readlink -f "$0")")"
+
+if [ $# -lt 2 ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
+  echo "Usage: $0 VERSION SYSEXTNAME [CNI_VERSION]"
+  echo "The script will download the Kubernetes release binaries (e.g., for v1.27.3) and create a sysext squashfs image with the name SYSEXTNAME.raw in the current folder."
+  echo "A temporary directory named SYSEXTNAME in the current folder will be created and deleted again."
+  echo "All files in the sysext image will be owned by root."
+  echo "To use arm64 pass 'ARCH=arm64' as environment variable (current value is '${ARCH}')."
+  echo "CNI version current value is 'latest'"
+  "${SCRIPTFOLDER}"/bake.sh --help
+  exit 1
+fi
+
+VERSION="$1"
+SYSEXTNAME="$2"
+CNI_VERSION="${3-latest}"
+if [ "${ARCH}" = aarch64 ]; then
+  ARCH=arm64
+fi
+rm -f kubectl kubeadm kubelet
+
+# install kubernetes binaries.
+curl -o kubectl -fsSL "https://dl.k8s.io/${VERSION}/bin/linux/${ARCH}/kubectl"
+curl -o kubeadm -fsSL "https://dl.k8s.io/${VERSION}/bin/linux/${ARCH}/kubeadm"
+curl -o kubelet -fsSL "https://dl.k8s.io/${VERSION}/bin/linux/${ARCH}/kubelet"
+
+rm -rf "${SYSEXTNAME}"
+mkdir -p "${SYSEXTNAME}"/usr/bin
+mv kubectl kubeadm kubelet "${SYSEXTNAME}"/usr/bin
+
+chmod +x "${SYSEXTNAME}"/usr/bin/{kubectl,kubeadm,kubelet}
+
+# setup kubelet service.
+mkdir -p "${SYSEXTNAME}/usr/lib/systemd/system"
+cat > "${SYSEXTNAME}/usr/lib/systemd/system/kubelet.service" <<-'EOF'
+[Unit]
+Description=kubelet: The Kubernetes Node Agent
+Documentation=https://kubernetes.io/docs/home/
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+ExecStart=/usr/bin/kubelet
+Restart=always
+StartLimitInterval=0
+RestartSec=10
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+mkdir -p "${SYSEXTNAME}/usr/lib/systemd/system/kubelet.service.d"
+cat > "${SYSEXTNAME}/usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf" <<-'EOF'
+# Note: This dropin only works with kubeadm and kubelet v1.11+
+[Service]
+Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
+Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
+# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
+EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
+# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
+# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
+EnvironmentFile=-/etc/sysconfig/kubelet
+ExecStart=
+ExecStartPre=/usr/bin/mkdir -p /opt/libexec /opt/libexec.work
+ExecStartPre=/usr/bin/cp -r /usr/local/bin/cni/ /opt/bin/cni
+ExecStartPre=/usr/bin/cp /usr/local/share/kubernetes-version /etc/kubernetes-version
+ExecStartPre=/usr/bin/mkdir -p /var/kubernetes/kubelet-plugins/volume/exec/
+ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS
+EOF
+
+mkdir -p "${SYSEXTNAME}/usr/local/share/"
+echo "${VERSION}" > "${SYSEXTNAME}/usr/local/share/kubernetes-version"
+
+mkdir -p "${SYSEXTNAME}/usr/libexec/kubernetes/kubelet-plugins/volume/exec/"
+# /var/kubernetes/... will be created at runtime by the kubelet unit.
+ln -sf "/var/kubernetes/kubelet-plugins/volume/exec/" "${SYSEXTNAME}/usr/libexec/kubernetes/kubelet-plugins/volume/exec/"
+
+mkdir -p "${SYSEXTNAME}/usr/lib/systemd/system/multi-user.target.d"
+{ echo "[Unit]"; echo "Upholds=kubelet.service"; } > "${SYSEXTNAME}/usr/lib/systemd/system/multi-user.target.d/10-kubelet-service.conf"
+
+# install CNI.
+version="${CNI_VERSION}"
+if [[ "${CNI_VERSION}" == "latest" ]]; then
+  version=$(curl -fsSL https://api.github.com/repos/containernetworking/plugins/releases/latest | jq -r .tag_name)
+  echo "Using latest version: ${version} for CNI plugins"
+fi
+curl -o cni.tgz -fsSL "https://github.com/containernetworking/plugins/releases/download/${version}/cni-plugins-linux-${ARCH}-${version}.tgz"
+mkdir -p "${SYSEXTNAME}/usr/local/bin/cni"
+tar --force-local -xf "cni.tgz" -C "${SYSEXTNAME}/usr/local/bin/cni"
+
+"${SCRIPTFOLDER}"/bake.sh "${SYSEXTNAME}"
+rm -rf "${SYSEXTNAME}"