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173 lines
7.1 KiB
Markdown
173 lines
7.1 KiB
Markdown
# Kyverno - Kubernetes Native Policy Management
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[](https://travis-ci.org/nirmata/kyverno) [](https://goreportcard.com/report/github.com/nirmata/kyverno)
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Kyverno is a policy engine designed for Kubernetes.
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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 maintain environment specific configurations separately from workload configurations.
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Kyverno allows cluster adminstrators to manage environment specific configurations independently of workload configurations and enforce configuration best practices for their clusters.
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Kyverno policies are Kubernetes resources that can be written in YAML or JSON. Kyverno policies can validate, mutate, and generate any Kubernetes resources.
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Kyverno runs as a [dynamic admission controller](https://kubernetes.io/docs/reference/access-authn-authz/extensible-admission-controllers/) 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.
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Kyverno policies can match resources using the resource kind, name, and label selectors. Wildcards are supported in names.
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Mutating policies can be written as overlays (similar to [Kustomize](https://kubernetes.io/docs/tasks/manage-kubernetes-objects/kustomization/#bases-and-overlays)) or as a [JSON Patch](http://jsonpatch.com/). Validating policies also use an overlay style syntax, with support for pattern matching and conditional (if-then-else) processing.
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Policy enforcement is captured using Kubernetes events. Kyverno also reports policy violations for existing resources.
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## Examples
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### 1. Validating resources
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This policy requires that all pods have CPU and memory resource requests and limits:
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````yaml
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apiVersion: kyverno.io/v1alpha1
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kind: Policy
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metadata:
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name: check-cpu-memory
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spec:
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rules:
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- name: check-pod-resources
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match:
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resources:
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kinds:
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- Pod
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validate:
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message: "CPU and memory resource requests and limits are required"
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pattern:
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spec:
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containers:
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# 'name: *' selects all containers in the pod
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- name: "*"
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resources:
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limits:
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# '?' requires 1 alphanumeric character and '*' means that there can be 0 or more characters.
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# Using them together e.g. '?*' requires at least one character.
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memory: "?*"
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cpu: "?*"
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requests:
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memory: "?*"
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cpu: "?*"
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````
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### 2. Mutating resources
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This policy sets the imagePullPolicy to Always if the image tag is latest:
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````yaml
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apiVersion: kyverno.io/v1alpha1
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kind: Policy
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metadata:
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name: set-image-pull-policy
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spec:
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rules:
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- name: set-image-pull-policy
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match:
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resources:
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kinds:
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- Deployment
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mutate:
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overlay:
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spec:
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template:
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spec:
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containers:
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# match images which end with :latest
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- (image): "*:latest"
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# set the imagePullPolicy to "Always"
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imagePullPolicy: "Always"
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````
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### 3. Generating resources
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This policy sets the Zookeeper and Kafka connection strings for all namespaces with a label key 'kafka'.
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````yaml
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apiVersion: kyverno.io/v1alpha1
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kind: Policy
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metadata:
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name: "zk-kafka-address"
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spec:
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rules:
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- name: "zk-kafka-address"
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match:
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resources:
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kinds:
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- Namespace
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selector:
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matchExpressions:
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- {key: kafka, operator: Exists}
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generate:
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kind: ConfigMap
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name: zk-kafka-address
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data:
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kind: ConfigMap
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data:
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ZK_ADDRESS: "192.168.10.10:2181,192.168.10.11:2181,192.168.10.12:2181"
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KAFKA_ADDRESS: "192.168.10.13:9092,192.168.10.14:9092,192.168.10.15:9092"
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````
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### 4. More examples
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Refer to a list of curated of [kyverno policies](/samples/README.md) to follow kubernetes best practices.
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## License
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[Apache License 2.0](https://github.com/nirmata/kyverno/blob/master/LICENSE)
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## Status
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*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.*
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## Alternatives
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### Open Policy Agent
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[Open Policy Agent (OPA)](https://www.openpolicyagent.org/) is a general-purpose policy engine that can be used as a Kubernetes admission controller. It supports a large set of use cases. Policies are written using [Rego](https://www.openpolicyagent.org/docs/latest/how-do-i-write-policies#what-is-rego) a custom query language.
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### Polaris
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[Polaris](https://github.com/reactiveops/polaris) validates configurations for best practices. It includes several checks across health, networking, security, etc. Checks can be assigned a severity. A dashboard reports the overall score.
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### External configuration management tools
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Tools like [Kustomize](https://github.com/kubernetes-sigs/kustomize) can be used to manage variations in configurations outside of clusters. There are several advantages to this approach when used to produce variations of the same base configuration. However, such solutions cannot be used to validate or enforce configurations.
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## Documentation
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* [Getting Started](documentation/installation.md)
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* [Writing Policies](documentation/writing-policies.md)
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* [Mutate](documentation/writing-policies-mutate.md)
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* [Validate](documentation/writing-policies-validate.md)
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* [Generate](documentation/writing-policies-generate.md)
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* [Testing Policies](documentation/testing-policies.md)
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* [Using kubectl](documentation/testing-policies.md#Test-using-kubectl)
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* [Using the Kyverno CLI](documentation/testing-policies.md#Test-using-the-Kyverno-CLI)
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## Roadmap
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Here are some the major features we plan on completing before a 1.0 release:
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* [Events](https://github.com/nirmata/kyverno/issues/14)
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* [Policy Violations](https://github.com/nirmata/kyverno/issues/24)
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* [Conditionals on existing resources](https://github.com/nirmata/kyverno/issues/57)
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* [Extend CLI to operate on cluster resources ](https://github.com/nirmata/kyverno/issues/164)
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## Getting help
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* For feature requests and bugs, file an [issue](https://github.com/nirmata/kyverno/issues).
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* For discussions or questions, join our [Kubernetes Slack channel #kyverno](https://app.slack.com/client/T09NY5SBT/CLGR9BJU9) or the [mailing list](https://groups.google.com/forum/#!forum/kyverno)
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## Contributing
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Welcome to our community and thanks for contributing!
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* Please review and agree to abide with the [Code of Conduct](/CODE_OF_CONDUCT.md) before contributing.
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* See the [Wiki](https://github.com/nirmata/kyverno/wiki) for developer documentation.
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* Browse through the [open issues](https://github.com/nirmata/kyverno/issues)
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