AWS Step Functions with Cloudwatch and Lambda

Triggering AWS Step Functions from CloudWatch rule to execute a series of Lambda Functions based on condition. Rules are cron jobs and set using Cloudwatch event rule. At some specified time it triggers the Step Function. The execution flow is as follows:

1. Cloudwatch rule triggers step function (the state machine).
2. Initial state fires a lambda named collector_lambda.
3. Collector lambda executes its job and then pass its output to the next state.
4. This state decides based on the output of the collector_lambda which lambda to call next.
5. Based on the decision of the state, either the sender_lambda or rejection_lambda is fired.
6. The fired lambda returns output and the state machine reach its end.

Commands To Manipulate Resources

First enter into terraform directory to run the following commands.

• Installs required terraform plugins. See more details here

terraform init

• View execution plan

terraform plan --var-file input_value.tfvars

• Apply the configurations

terraform apply --var-file input_value.tfvars --auto-approve

Remove --auto-approve option from the above command to approve manually (by inputting prompt).

If the input file is named exactly terraform.tfvars or any variation of *.auto.tfvars, those will be loaded automatically, you don't need to pass --var-file option with the command. In this case the command is as following.

terraform apply --auto-approve

And, the JSON version of the input files follows the same above rules.

• Destroy all resources

terraform destroy --var-file input.tfvars --auto-approve

Remove --auto-approve option from the above command to approve manually (by inputting prompt).