templates

type Config ¶

type Config struct {
	AdditionalIndentation uint
	DisabledFunctions     []string
	EncryptionConfig
	KubeAPIResourceList []*metav1.APIResourceList
	LookupNamespace     string
	StartDelim          string
	StopDelim           string
}

Config is a struct containing configuration for the API. Some are required.

- AdditionalIndentation sets the number of additional spaces to be added to the input number to the indent method. This is useful in situations when the indentation should be relative to a logical starting point in a YAML file.

- DisabledFunctions is a slice of default template function names that should be disabled. - KubeAPIResourceList sets the cache for the Kubernetes API resources. If this is set, template processing will not try to rediscover the Kubernetes API resources needed for dynamic client/ GVK lookups.

- EncryptionConfig is the configuration for template encryption/decryption functionality.

- InitializationVector is the initialization vector (IV) used in the AES-CBC encryption/decryption. Note that it must be equal to the AES block size which is always 128 bits (16 bytes). This value must be random but does not need to be private. Its purpose is to make the same plaintext value, when encrypted with the same AES key, appear unique. When performing decryption, the IV must be the same as it was for the encryption of the data. Note that all values encrypted in the template will use this same IV, which means that duplicate plaintext values that are encrypted will yield the same encrypted value in the template.

- LookupNamespace is the namespace to restrict "lookup" template functions (e.g. fromConfigMap) to. If this is not set (i.e. an empty string), then all namespaces can be used.

- StartDelim customizes the start delimiter used to distinguish a template action. This defaults to "{{". If StopDelim is set, this must also be set.

- StopDelim customizes the stop delimiter used to distinguish a template action. This defaults to "}}". If StartDelim is set, this must also be set.

type EncryptionConfig ¶

type EncryptionConfig struct {
	AESKey                []byte
	AESKeyFallback        []byte
	DecryptionConcurrency uint8
	DecryptionEnabled     bool
	EncryptionEnabled     bool
	InitializationVector  []byte
}

EncryptionConfig is a struct containing configuration for template encryption/decryption functionality.

- AESKey is an AES key (e.g. AES-256) to use for the "protect" template function and decrypting such values.

- AESKeyFallback is an AES key to try if the decryption fails using AESKey.

- DecryptionConcurrency is the concurrency (i.e. number of Goroutines) limit when decrypting encrypted strings. Not setting this value is the equivalent of setting this to 1, which means no concurrency.

- DecryptionEnabled enables automatic decrypting of encrypted strings. AESKey and InitializationVector must also be set if this is enabled.

- EncryptionEnabled enables the "protect" template function and "fromSecret" returns encrypted content. AESKey and InitializationVector must also be set if this is enabled.

- InitializationVector is the initialization vector (IV) used in the AES-CBC encryption/decryption. Note that it must be equal to the AES block size which is always 128 bits (16 bytes). This value must be random but does not need to be private. Its purpose is to make the same plaintext value, when encrypted with the same AES key, appear unique. When performing decryption, the IV must be the same as it was for the encryption of the data. Note that all values encrypted in the template will use this same IV, which means that duplicate plaintext values that are encrypted will yield the same encrypted value in the template.

type TemplateResolver ¶

type TemplateResolver struct {
	// contains filtered or unexported fields
}

TemplateResolver is the API for processing templates. It's better to use the NewResolver function instead of instantiating this directly so that configuration defaults and validation are applied.

func NewResolver(kubeClient *kubernetes.Interface, kubeConfig *rest.Config, config Config) (*TemplateResolver, error)

func (t *TemplateResolver) ResolveTemplate(tmplJSON []byte, context interface{}) ([]byte, error)

policyYAML := `
---
apiVersion: policy.open-cluster-management.io/v1
kind: ConfigurationPolicy
metadata:
  name: demo-sampleapp-config
  namespace: sampleapp
spec:
  remediationAction: enforce
  namespaceSelector:
    exclude:
    - kube-*
    include:
    - default
  object-templates:
  - complianceType: musthave
    objectDefinition:
      kind: ConfigMap
      apiVersion: v1
      metadata:
        name: demo-sampleapp-config
        namespace: test
      data:
        message: '{{ "VGVtcGxhdGVzIHJvY2sh" | base64dec }}'
        b64-cluster-name: '{{ .ClusterName | base64enc }}'
    severity: high
`

policyJSON, err := yamlToJSON([]byte(policyYAML))
if err != nil {
	fmt.Fprintf(os.Stderr, "Failed to convert the policy YAML to JSON: %v\n", err)
	panic(err)
}

// This example uses the fake Kubernetes client, but in production, use a
// real Kubernetes configuration and client
var k8sClient kubernetes.Interface = fake.NewSimpleClientset()

resolver, err := NewResolver(&k8sClient, &rest.Config{}, Config{})
if err != nil {
	fmt.Fprintf(os.Stderr, "Failed to instantiate the templatesResolver struct: %v\n", err)
	panic(err)
}

templateContext := struct{ ClusterName string }{ClusterName: "cluster0001"}

policyResolvedJSON, err := resolver.ResolveTemplate(policyJSON, templateContext)
if err != nil {
	fmt.Fprintf(os.Stderr, "Failed to process the policy YAML: %v\n", err)
	panic(err)
}

var policyResolved interface{}
err = yaml.Unmarshal(policyResolvedJSON, &policyResolved)

objTmpls := policyResolved.(map[string]interface{})["spec"].(map[string]interface{})["object-templates"]
objDef := objTmpls.([]interface{})[0].(map[string]interface{})["objectDefinition"]

data, ok := objDef.(map[string]interface{})["data"].(map[string]interface{})
if !ok {
	fmt.Fprintf(os.Stderr, "Failed to process the policy YAML: %v\n", err)
	panic(err)
}

message, ok := data["message"].(string)
if !ok {
	fmt.Fprintf(os.Stderr, "Failed to process the policy YAML: %v\n", err)
	panic(err)
}

b64ClusterName, ok := data["b64-cluster-name"].(string)
if !ok {
	fmt.Fprintf(os.Stderr, "Failed to process the policy YAML: %v\n", err)
	panic(err)
}

fmt.Println(message)
fmt.Println(b64ClusterName)

Output:

Templates rock!
Y2x1c3RlcjAwMDE=

func (t *TemplateResolver) SetEncryptionConfig(encryptionConfig EncryptionConfig) error

func (t *TemplateResolver) SetKubeAPIResourceList(resourceList []*metav1.APIResourceList)