Discussion on: How to setup a Serverless application with AWS SAM and Terraform

[johannes-mathes]

Really interesting idea. I followed your example.
In my organziation, we already use CodeBuild and CodePipeline for terraform deployments.
We deploy also our ECS fargate services via terraform and additional CodeDeploy steps.

I mixed our terraform CodeBuild stuff and your example and we have a pipeline which does a terraform plan, approval action with the plan, a terraform deploy and then the create changeset and execute changeset.

For the communication between terraform and CloudFormation I did not use SSM parameters. I defined parameters in the CloudFormation template.
According the SAM / CF documentation you can either override such parameters in CodePipeline or you can specify a configuration.json

The trick I did is that my terraform output is directly the output for the configuration json.
So in my terraform apply step in CodeBuild I do
terraform apply -input=false -lock-timeout=30s ./.pipeline/plan.tfplan

and then I do terraform output -json | jq .configuration_cloudformation.value > configuration.json

My terraform output statement looks like:

output "configuration_cloudformation" {
value = {
Parameters = {
SecurityGroupIds = aws_security_group.lambda.id
LambdaRoleARN = aws_iam_role.jds_monitoring.arn
Tags = var.complete_tags
...
StackPolicy = {
}
}

[Rolf Streefkerk]

That kind of chaining would solve the issue, thanks for sharing.