> For the complete documentation index, see [llms.txt](https://atomoh.gitbook.io/kubernetes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://atomoh.gitbook.io/kubernetes/en/service-mesh/istio/advanced/07-sidecar-injection.md).

# Sidecar Injection

Sidecar Injection is the mechanism by which Istio automatically injects the Envoy proxy into application pods.

## Overview

Sidecar Injection methods:

* Automatic injection (Webhook)
* Manual injection (istioctl)

## Automatic Injection Configuration

### Namespace Level

```bash
# Add Label to Namespace
kubectl label namespace default istio-injection=enabled

# Verify
kubectl get namespace default -L istio-injection
```

### Pod Level

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: myapp
  annotations:
    sidecar.istio.io/inject: "true"  # Inject only this pod
spec:
  containers:
  - name: myapp
    image: myapp:latest
```

## Manual Injection

```bash
# Inject Sidecar into manifest
istioctl kube-inject -f deployment.yaml | kubectl apply -f -

# Or save to file
istioctl kube-inject -f deployment.yaml -o deployment-injected.yaml
kubectl apply -f deployment-injected.yaml
```

## Sidecar Resource Configuration

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: myapp
  annotations:
    sidecar.istio.io/proxyCPU: "100m"
    sidecar.istio.io/proxyMemory: "128Mi"
    sidecar.istio.io/proxyCPULimit: "200m"
    sidecar.istio.io/proxyMemoryLimit: "256Mi"
spec:
  containers:
  - name: myapp
    image: myapp:latest
```

## Excluding from Injection

```yaml
# Exclude specific pod
apiVersion: v1
kind: Pod
metadata:
  name: myapp
  annotations:
    sidecar.istio.io/inject: "false"
spec:
  containers:
  - name: myapp
    image: myapp:latest
```

## Troubleshooting

```bash
# Check injection status
kubectl get namespace default -o yaml | grep istio-injection

# Check webhook
kubectl get mutatingwebhookconfigurations

# Check sidecar
kubectl get pods -n default -o jsonpath='{.items[*].spec.containers[*].name}'
```

## References

* [Istio Sidecar Injection](https://istio.io/latest/docs/setup/additional-setup/sidecar-injection/)