Inject Sidecar Container

 1apiVersion: kyverno.io/v1
 2kind: ClusterPolicy
 3metadata:
 4  name: inject-sidecar
 5  annotations:
 6    policies.kyverno.io/title: Inject Sidecar Container
 7    policies.kyverno.io/category: Sample
 8    policies.kyverno.io/subject: Pod,Volume
 9    policies.kyverno.io/description: >-
10      The sidecar pattern is very common in Kubernetes whereby other applications can
11      insert components via tacit modification of a submitted resource. This is, for example,
12      often how service meshes and secrets applications are able to function transparently.
13      This policy injects a sidecar container, initContainer, and volume into Pods that match
14      an annotation called `vault.hashicorp.com/agent-inject: true`.      
15spec:
16  rules:
17  - name: inject-sidecar
18    match:
19      resources:
20        kinds:
21        - Deployment
22    mutate:
23      patchStrategicMerge:
24        spec:
25          template:
26            metadata:
27              annotations:
28                (vault.hashicorp.com/agent-inject): "true"
29            spec:
30              containers:
31              - name: vault-agent
32                image: vault:1.5.4
33                imagePullPolicy: IfNotPresent
34                volumeMounts:
35                - mountPath: /vault/secrets
36                  name: vault-secret
37              initContainers:
38              - name: vault-agent-init
39                image: vault:1.5.4
40                imagePullPolicy: IfNotPresent
41                volumeMounts:
42                - mountPath: /vault/secrets
43                  name: vault-secret
44              volumes:
45              - name: vault-secret
46                emptyDir:
47                  medium: Memory