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167 lines
7.4 KiB
Markdown
167 lines
7.4 KiB
Markdown
# Kubeconform
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[](https://github.com/yannh/kubeconform/actions?query=branch%3Amaster)
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[](https://goreportcard.com/report/github.com/yannh/kubeconform)
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Kubeconform is a Kubernetes manifests validation tool. Build it into your CI to validate your Kubernetes
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configuration using the schemas from the registry maintained by the
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[kubernetes-json-schema](https://github.com/instrumenta/kubernetes-json-schema) project!
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It is inspired by, contains code from and is designed to stay close to
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[Kubeval](https://github.com/instrumenta/kubeval), but with the following improvements:
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* **high performance**: will validate & download manifests over multiple routines, caching
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downloaded files in memory
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* configurable list of **remote, or local schemas locations**, enabling validating Kubernetes
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custom resources (CRDs)
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### A small overview of Kubernetes manifest validation
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Kubernetes's API is described using the [OpenAPI (formerly swagger) specification](https://www.openapis.org),
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in a [file](https://github.com/kubernetes/kubernetes/blob/master/api/openapi-spec/swagger.json) checked into
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the main Kubernetes repository.
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Because of the state of the tooling to perform validation against OpenAPI schemas, projects usually convert
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the OpenAPI schemas to [JSON schemas](https://json-schema.org/) first. Kubeval relies on
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[instrumenta/OpenApi2JsonSchema](https://github.com/instrumenta/openapi2jsonschema) to convert Kubernetes' Swagger file
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and break it down into multiple JSON schemas, stored in github at
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[instrumenta/kubernetes-json-schema](https://github.com/instrumenta/kubernetes-json-schema) and published on
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[kubernetesjsonschema.dev](https://kubernetesjsonschema.dev/).
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Kubeconform relies on the same JSON schemas from kubernetesjsonschema.dev, and will download required
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schemas at runtime as required.
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### Limits of Kubeconform validation
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Kubeconform, similarly to kubeval, only validates manifests using the OpenAPI specifications. In some
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cases, the Kubernetes controllers might perform additional validation - so that manifests passing kubeval
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validation would still error when being deployed. See for example these bugs against kubeval:
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[#253](https://github.com/instrumenta/kubeval/issues/253)
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[#256](https://github.com/instrumenta/kubeval/issues/256)
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[#257](https://github.com/instrumenta/kubeval/issues/257)
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[#259](https://github.com/instrumenta/kubeval/issues/259). The validation logic mentioned in these
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bug reports is not part of Kubernetes' OpenAPI spec, and therefore kubeconform/kubeval will not detect the
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configuration errors.
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### Usage
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```
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$ ./bin/kubeconform -h
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Usage of ./bin/kubeconform:
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-ignore-missing-schemas
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skip files with missing schemas instead of failing
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-kubernetes-version string
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version of Kubernetes to validate against (default "1.18.0")
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-n int
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number of routines to run in parallel (default 4)
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-output string
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output format - text, json (default "text")
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-schema-location value
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override schemas location search path (can be specified multiple times)
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-skip string
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comma-separated list of kinds to ignore
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-strict
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disallow additional properties not in schema
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-summary
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print a summary at the end
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-verbose
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print results for all resources
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```
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### Usage examples
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* Validating a single, valid file
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```
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$ ./bin/kubeconform fixtures/valid.yaml
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$ echo $?
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0
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```
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* Validating a single invalid file, setting output to json, and printing a summary
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```
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$ ./bin/kubeconform -summary -output json fixtures/invalid.yaml
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{
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"resources": [
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{
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"filename": "fixtures/invalid.yaml",
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"kind": "ReplicationController",
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"version": "v1",
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"status": "INVALID",
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"msg": "Additional property templates is not allowed - Invalid type. Expected: [integer,null], given: string"
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}
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],
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"summary": {
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"valid": 0,
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"invalid": 1,
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"errors": 0,
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"skipped": 0
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}
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}
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$ echo $?
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1
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```
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* Passing manifests via Stdin
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```
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cat fixtures/valid.yaml | ./bin/kubeconform -summary
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Summary: 1 resource found parsing stdin - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0
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```
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* Validating a folder, increasing the number of parallel workers
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```
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$ ./bin/kubeconform -summary -n 16 fixtures
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fixtures/crd_schema.yaml - CustomResourceDefinition trainingjobs.sagemaker.aws.amazon.com failed validation: could not find schema for CustomResourceDefinition
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fixtures/invalid.yaml - ReplicationController bob is invalid: Invalid type. Expected: [integer,null], given: string
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[...]
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Summary: 65 resources found in 34 files - Valid: 55, Invalid: 2, Errors: 8 Skipped: 0
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```
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### Overriding schemas location - CRD and Openshift support
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When the `-schema-location` parameter is not used, kubeconform will default to downloading schemas from
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`https://kubernetesjsonschema.dev`. Kubeconform however supports passing one, or multiple, schemas
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locations - HTTP URLs, or local filesystem paths, in which case it will lookup for schema definitions
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in each of them, in order, stopping as soon as a matching file is found.
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* If the -schema-location value does not end with '.json', Kubeconform will assume filenames / a file
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structure identical to that of kubernetesjsonschema.dev
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* if the -schema-location value ends with '.json' - Kubeconform assumes the value is a Go templated
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string that indicates how to search for JSON schemas.
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All 3 following command lines are equivalent:
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```
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$ ./bin/kubeconform fixtures/valid.yaml
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$ ./bin/kubeconform -schema-location https://kubernetesjsonschema.dev fixtures/valid.yaml
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$ ./bin/kubeconform -schema-location 'https://kubernetesjsonschema.dev/{{ .NormalizedVersion }}-standalone{{ .StrictSuffix }}/{{ .ResourceKind }}{{ .KindSuffix }}.json' fixtures/valid.yaml
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```
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To support validating CRDs, we need to convert OpenAPI files to JSON schema, storing the JSON schemas
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in a local folder - for example schemas. Then we specify this folder as an additional registry to lookup:
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```
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# If the resource Kind is not found in kubernetesjsonschema.dev, also lookup in the schemas/ folder for a matching file
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$ ./bin/kubeconform -registry https://kubernetesjsonschema.dev -schema-location 'schemas/{{ .ResourceKind }}{{ .KindSuffix }}.json' fixtures/custom-resource.yaml
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```
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You can validate Openshift manifests using a custom schema location. Set the OpenShift version to validate
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against using -kubernetes-version.
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```
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bin/kubeconform -kubernetes-version 3.8.0 -schema-location 'https://raw.githubusercontent.com/garethr/openshift-json-schema/master/{{ .NormalizedVersion }}-standalone{{ .StrictSuffix }}/{{ .ResourceKind }}.json' -summary fixtures/valid.yaml
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Summary: 1 resource found in 1 file - Valid: 1, Invalid: 0, Errors: 0 Skipped: 0
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```
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### Converting an OpenAPI file to a JSON Schema
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Kubeconform uses JSON schemas to validate Kubernetes resources. For Custom Resource, the CustomResourceDefinition
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first needs to be converted to JSON Schema. A script is provided to convert these CustomResourceDefinitions
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to JSON schema. Here is an example how to use it:
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```
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$ ./scripts/openapi2jsonschema.py https://raw.githubusercontent.com/aws/amazon-sagemaker-operator-for-k8s/master/config/crd/bases/sagemaker.aws.amazon.com_trainingjobs.yaml > fixtures/registry/trainingjob-sagemaker-v1.json
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```
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### Credits
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* @garethr for the [Kubeval](https://github.com/instrumenta/kubeval) and
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[kubernetes-json-schema](https://github.com/instrumenta/kubernetes-json-schema) projects ❤️
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