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README.md |
Kyverno - Kubernetes Native Policy Management
Kyverno is a policy engine designed for Kubernetes.
Kubernetes supports declarative management of objects using configurations written in YAML or JSON. Often, parts of the configuration will need to vary based on the runtime environment. For portability, and for separation of concerns, its best to mantain environment specific configurations separately from workload configurations.
Kyverno allows cluster adminstrators to manage environment specific configurations independently of workload configurations and enforce configuration best practices for their clusters.
Kyverno policies are Kubernetes resources that can be written in YAML or JSON. Kyverno policies can validate, mutate, and generate any Kubernetes resources.
Kyverno runs as a dynamic admission controller in a Kubernetes cluster. Kyverno receives validating and mutating admission webhook HTTP callbacks from the kube-apiserver and applies matching policies to return results that enforce admission policies or reject requests.
Kyverno policies can match resources using the resource kind, name, and label selectors. Wildcards are supported in names.
Mutating policies can be written as overlays (similar to Kustomize) or as a JSON Patch. Validating policies also use an overlay style syntax, with support for pattern matching and conditional (if-then-else) processing.
Policy enforcement is captured using Kubernetes events. Kyverno also reports policy violations for existing resources.
Examples
1. Validating resources
This policy requires that all pods have CPU and memory resource requests and limits:
apiVersion: kyverno.io/v1alpha1
kind: Policy
metadata:
name: check-cpu-memory
spec:
rules:
- name: check-pod-resources
resource:
kinds:
- Pod
validate:
message: "CPU and memory resource requests and limits are required"
pattern:
spec:
containers:
# 'name: *' selects all containers in the pod
- name: "*"
resources:
limits:
# '?' requires at least 1 character and '*' means that there can be 0 or several characters after a single character marked by ?
memory: "?*"
cpu: "?*"
requests:
memory: "?*"
cpu: "?*"
2. Mutating resources
This policy sets the imagePullPolicy to Always if the image tag is latest:
apiVersion: kyverno.io/v1alpha1
kind: Policy
metadata:
name: set-image-pull-policy
spec:
rules:
- name: set-image-pull-policy
resource:
kinds:
- Pod
mutate:
overlay:
spec:
containers:
# match images which end with :latest
- (image): "*:latest"
# set the imagePullPolicy to "Always"
imagePullPolicy: "Always"
3. Generating resources
This policy sets the Zookeeper and Kafka connection strings for all namespaces with a label key 'kafka'.
apiVersion: kyverno.io/v1alpha1
kind: Policy
metadata:
name: "zk-kafka-address"
spec:
rules:
- name: "zk-kafka-address"
resource:
kinds:
- Namespace
selector:
matchExpressions:
- {key: kafka, operator: Exists}
generate:
kind: ConfigMap
name: zk-kafka-address
data:
ZK_ADDRESS: "192.168.10.10:2181,192.168.10.11:2181,192.168.10.12:2181"
KAFKA_ADDRESS: "192.168.10.13:9092,192.168.10.14:9092,192.168.10.15:9092"
4. More examples
Additional examples are available in examples.
Status
Kyverno is under active development and not ready for production use. Key components and policy definitions are likely to change as we complete core features.
Documentation
Roadmap
Here are some the major features we plan on completing before a 1.0 release:
- Events
- Policy Violations
- Generate any resource
- Conditionals on existing resources
- Extend CLI to operate on cluster resources
Getting help
For feature requests and bugs, file an issue.