Kubernetes v1.28 SidecarContainers — An API for sidecar containers

Philippe Bogaerts
4 min readAug 16


As per Kubernetes documentation , K8S now allows you to specify a restartPolicy for init containers which is independent of the Pod and other init containers.

This features is available starting with Kubernetes 1.28 in alpha through a feature gate named SidecarContainers. Alpha features are NOT enabled by default.

Through the years, I have been researching different ways to capture traffic in pods (see references). So here we go again!

Maintained and updated here:

How to enable the feature gate

I compiled a small step-by-step install for a self-managed #k8s setup

  • Create 3 ubuntu nodes
  • On the control-plane node:
curl https://raw.githubusercontent.com/xxradar/k8s-calico-oss-install-containerd/main/setup-cluster-config.sh | bash
  • On the worker nodes:
curl https://raw.githubusercontent.com/xxradar/install_k8s_ubuntu/main/setup_node_latest.sh | bash
  • Run the join command on the worker nodes
    (copy/paste output from control-plane node)
sudo kubeadm join --token eow8gw.8863eelhollpn37p \
--discovery-token-ca-cert-hash sha256:1e0ec482fcee39edbfzxxzxz5e6a7e57217bd1e57c23e2d318ef7e16759947

Install a CNI

You can use any CNI. Here we use https://cilium.io/ v1.14.

CILIUM_CLI_VERSION=$(curl -s https://raw.githubusercontent.com/cilium/cilium-cli/main/stable.txt)
if [ "$(uname -m)" = "aarch64" ]; then CLI_ARCH=arm64; fi
curl -L --fail --remote-name-all https://github.com/cilium/cilium-cli/releases/download/${CILIUM_CLI_VERSION}/cilium-linux-${CLI_ARCH}.tar.gz{,.sha256sum}
sha256sum --check cilium-linux-${CLI_ARCH}.tar.gz.sha256sum
sudo tar xzvfC cilium-linux-${CLI_ARCH}.tar.gz /usr/local/bin
rm cilium-linux-${CLI_ARCH}.tar.gz{,.sha256sum}
sudo snap install helm --classic
helm repo add cilium https://helm.cilium.io/
helm install cilium cilium/cilium --version…
Philippe Bogaerts

#BruCON co-founder, #OWASP supporter, Application Delivery and Web Application Security, #Kubernetes and #container, #pentesting enthousiast, BBQ & cocktails !!