Documentation
¶
Overview ¶
Package cfn provides helpers for implementing AWS CloudFormation custom resources.
CloudFormation custom resources allow you to write custom provisioning logic that CloudFormation runs when you create, update, or delete stacks. This package handles the response protocol, making it easier to implement custom resource handlers.
The LambdaWrap helper catches errors and ensures proper responses are sent to CloudFormation's pre-signed URL, preventing stack operations from hanging.
See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-custom-resources.html
Example ¶
CloudFormation custom resources require a different response handling due to the way stacks execute. The cfn.LambdaWrap helper catches all errors and ensures the correct response is sent to the pre-signed URL that comes with the event.
This example safely 'Echo' back anything given into the Echo parameter within the Custom Resource call.
package main
import (
"context"
"github.com/aws/aws-lambda-go/cfn"
"github.com/aws/aws-lambda-go/lambda"
)
func main() {
lambda.Start(cfn.LambdaWrap(func(ctx context.Context, event cfn.Event) (physicalResourceID string, data map[string]interface{}, err error) {
v, _ := event.ResourceProperties["Echo"].(string)
data = map[string]interface{}{
"Echo": v,
}
return
}))
}
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type CustomResourceFunction ¶
type CustomResourceFunction func(context.Context, Event) (physicalResourceID string, data map[string]interface{}, err error)
CustomResourceFunction is a representation of the customer's Custom Resource function. LambdaWrap will take the returned values and turn them into a response to be sent to CloudFormation.
type CustomResourceLambdaFunction ¶
CustomResourceLambdaFunction is a standard form Lambda for a Custom Resource.
func LambdaWrap ¶
func LambdaWrap(lambdaFunction CustomResourceFunction) (fn CustomResourceLambdaFunction)
LambdaWrap returns a CustomResourceLambdaFunction which is something lambda.Start() will understand. The purpose of doing this is so that Response Handling boiler plate is taken away from the customer and it makes writing a Custom Resource simpler.
func myLambda(ctx context.Context, event cfn.Event) (physicalResourceID string, data map[string]interface{}, err error) {
physicalResourceID = "arn:...."
return
}
func main() {
lambda.Start(cfn.LambdaWrap(myLambda))
}
type Event ¶
type Event struct {
RequestType RequestType `json:"RequestType"`
RequestID string `json:"RequestId"`
ResponseURL string `json:"ResponseURL"`
ResourceType string `json:"ResourceType"`
PhysicalResourceID string `json:"PhysicalResourceId,omitempty"`
LogicalResourceID string `json:"LogicalResourceId"`
StackID string `json:"StackId"`
ResourceProperties map[string]interface{} `json:"ResourceProperties"`
OldResourceProperties map[string]interface{} `json:"OldResourceProperties,omitempty"`
}
Event is a representation of a Custom Resource request
type RequestType ¶
type RequestType string
RequestType represents the types of requests that come from a CloudFormation stack being run
const ( RequestCreate RequestType = "Create" RequestUpdate RequestType = "Update" RequestDelete RequestType = "Delete" )
type Response ¶
type Response struct {
Status StatusType `json:"Status"`
RequestID string `json:"RequestId"`
LogicalResourceID string `json:"LogicalResourceId"`
StackID string `json:"StackId"`
PhysicalResourceID string `json:"PhysicalResourceId"`
Reason string `json:"Reason,omitempty"`
NoEcho bool `json:"NoEcho,omitempty"`
Data map[string]interface{} `json:"Data,omitempty"`
// contains filtered or unexported fields
}
Response is a representation of a Custom Resource response expected by CloudFormation.
func NewResponse ¶
NewResponse creates a Response with the relevant verbatim copied data from a Event
type SNSCustomResourceLambdaFunction ¶ added in v1.12.0
type SNSCustomResourceLambdaFunction func(context.Context, events.SNSEvent) (reason string, err error)
SNSCustomResourceLambdaFunction is a standard form Lambda for a Custom Resource that is triggered via a SNS topic.
func LambdaWrapSNS ¶ added in v1.12.0
func LambdaWrapSNS(lambdaFunction CustomResourceFunction) SNSCustomResourceLambdaFunction
LambdaWrapSNS wraps a Lambda handler with support for SNS-based custom resources. Usage and purpose otherwise same as LambdaWrap().
type StatusType ¶
type StatusType string
StatusType represents a CloudFormation response status
const ( StatusSuccess StatusType = "SUCCESS" StatusFailed StatusType = "FAILED" )
Source Files