cfn-custom-resources

AWS CloudFormation : Usefull custom resources

Instructions

You will create 2 custom resources for your CloudFormation templates :

A resource to retrieve credentials in Secrets Manager.
A resource str-utils to make operations on strings, that's not natively included in CF for now.

Create the secrets

aws secretsmanager create-secret --name "test/creds" --secret-string file://creds.json

# You can retrieve them in the cli like this : 
aws secretsmanager get-secret-value --secret-id "test/creds"

Create your own S3 bucket, where you can store artifacts about CloudFormation and Lambda

cp cfn/params.json.dist cfn/params.json
# then edit cfn/params.json
# and set a unique name for your S3 bucket (the names are shared between AWS accounts)

aws cloudformation create-stack --stack-name cfn-exercise-s3 --template-body file://./cfn/create-s3.yml --parameters file://./cfn/params.json

Deploy your lambda functions to S3

./deploy-lambda.sh <my-bucket>

Create the lambda functions to be used by the custom resources

aws cloudformation create-stack --stack-name cfn-exercise-lambda-functions --template-body file://./cfn/create-lambda-functions.yml --parameters file://./cfn/params.json --capabilities CAPABILITY_NAMED_IAM

Execute the custom resources directly from a new stack

aws cloudformation create-stack --stack-name cfn-exercise-custom-resources-usage --template-body file://./cfn/custom-resources-usage.yml --timeout-in-minutes 5

Now you should see your outputs processed by the custom ressources !

Clean up

Once it's done, you should delete your stacks

aws cloudformation delete-stack --stack-name cfn-exercise-custom-resources-usage
aws cloudformation delete-stack --stack-name cfn-exercise-lambda-functions
aws cloudformation delete-stack --stack-name cfn-exercise-s3

Credits

The cfn_resource.py function is based on the cfn-wrapper-python repository by ryansb.

jdxlabs/cfn-custom-resources