Istio has the ability to install itself as a sidecar automatically by using labels in the namespace. We can make it function in this way by using the following steps:

1. Let's label the default namespace with the appropriate label, namely, istio-injection=enabled:

kubectl label namespace default istio-injection=enabled

2. Let's launch an application to see whether the sidecar is indeed deployed automatically:

kubectl apply -f samples/bookinfo/platform/kube/bookinfo.yaml

3. Get the pods running on the default namespace:

kubectl get pods

4. Run the describe command on any one of the pods:

kc describe pods/details-<pod id>

You can see that the sidecar has indeed been applied:

Name:           details-v1-7bcdcc4fd6-xqwjz
Namespace:      default
...
Labels:         app=details
                pod-template-hash=3678770982
                version=v1
Annotations:    sidecar.istio.io/status:
                  {"version":"887285bb7fa76191bf7f637f283183f0ba057323b078d44c3db45978346cbc1a","initContainers":["istio-init"],"containers":["istio-proxy"]...
...

Note that without making any modifications to the underlying application, we were able to get the istio service mesh deployed and attached to the containers.