Kubernetes Mutating Webhook

https://hub.docker.com/r/expediagroup/kubernetes-sidecar-injector

This mutating webhook was developed to inject sidecars to a Kubernetes pod.

Developing

If one is interested in contributing to this codebase, please read the developer documentation on how to build and test this codebase.

Using this webhook

We have provided two ways to deploy this webhook. Using Helm and using kubectl. Deployment files are in deployment/helm and deployment/kubectl respectively.

ConfigMap Sidecar Configuration

NOTE: Applications only have access to sidecars in their own namespaces.

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-app-sidecar
  namespace: my-app-namespace
data:
  sidecars.yaml: |
    - name: # Sidcar Name
      initContainers:
        - name: # Example 1
          image: # Example 1
      containers:
        - name: # Example 2
          image: # Example 2
      volumes:
        - name: # Example 3
          configMap:
            name: # Example 3
      imagePullSecrets:
        - name: # Example 4

How to enable sidecar injection using this webhook

Deploy this mutating webhook by cloning this repository and running the following command (needs kubectl installed and configured to point to the kubernetes cluster or minikube)

make helm-install

By default, all namespaces are watched except kube-system and kube-public. This can be configured in your helm values.
Add the annotation (sidecar-injector.expedia.com/inject by default) with ConfigMap sidecar name to inject in pod spec where sidecar needs to be injected. This sample spec shows such an annotation added to a pod spec to inject haystack-agent.
Create your ConfigMap sidecar configuration

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-app-sidecar
  namespace: {{ .Release.Namespace }}
data:
  sidecars.yaml: |
    - name: busybox
      initContainers:
        - name: busybox
          image: busybox
          command: [ "/bin/sh" ]
          args: [ "-c", "echo '<html><h1>Hi!</h1><html>' >> /work-dir/index.html" ]
          volumeMounts:
            - name: workdir
              mountPath: "/work-dir"

How to use the kubernetes-sidecar-injector Helm repository

You need to add this repository to your Helm repositories: