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resource_template.go
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resource_template.go
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package v3
import (
"bytes"
"encoding/json"
"fmt"
"html/template"
corev2 "github.com/sensu/core/v2"
apitools "github.com/sensu/sensu-api-tools"
)
// ResourceTemplate is a template for core/v3 resources.
type ResourceTemplate struct {
Metadata *corev2.ObjectMeta `json:"metadata"`
APIVersion string `json:"api_version"`
Type string `json:"type"`
Template string `json:"template"`
}
func (r *ResourceTemplate) GetMetadata() *corev2.ObjectMeta {
return r.Metadata
}
// Execute executes the Template in the ResourceTemplate. It's given a metadata
// object to draw variables from. Typically, templating will be done with a
// variable namespace or name, but could also be done with labels and annotations
// from the metadata, depending on the nature of the template.
func (r *ResourceTemplate) Execute(meta *corev2.ObjectMeta) (Resource, error) {
tmpl, err := template.New("resource").Parse(r.Template)
if err != nil {
return nil, fmt.Errorf("error parsing resource template: %s", err)
}
var buf bytes.Buffer
if err := tmpl.Execute(&buf, meta); err != nil {
return nil, fmt.Errorf("error executing resource template: %s", err)
}
t, err := apitools.Resolve(r.APIVersion, r.Type)
if err != nil {
// do not wrap this error
return nil, err
}
resource, ok := t.(Resource)
if !ok {
return nil, fmt.Errorf("error expanding resource template: %T is not a core/v3 resource", t)
}
if err := json.Unmarshal(buf.Bytes(), &resource); err != nil {
return nil, fmt.Errorf("error expanding resource template: invalid json: %s", err)
}
if err := resource.Validate(); err != nil {
return nil, fmt.Errorf("error expanding resource template: resource not valid: %s", err)
}
return resource, nil
}
func (r *ResourceTemplate) validate() error {
if _, err := template.New("validate").Parse(r.Template); err != nil {
return err
}
if _, err := apitools.Resolve(r.APIVersion, r.Type); err != nil {
return err
}
return nil
}