Cannot terraform apply minor changes with multiple workers due to a module cycle

[julnamoo]

Problem

I have tried to reuse AWS resources after the first terraform apply. In a way running the apply command with this, -var='locat_plan_filename="script1.py"' , but the apply failed with the below logs.

Logs

⚡  terraform plan
Acquiring state lock. This may take a few moments...
module.locust.tls_private_key.loadtest: Refreshing state... [id=a5b616973aaf0f278d108eb3d874fed573c0ca87]
module.locust.aws_key_pair.loadtest: Refreshing state... [id=locuster-dist-loadtest-keypair]
module.locust.data.aws_subnet.current: Reading...
module.locust.data.aws_ami.amazon_linux_2: Reading...
module.locust.aws_iam_role.loadtest: Refreshing state... [id=locuster-dist-loadtest-role]
module.locust.null_resource.key_pair_exporter: Refreshing state... [id=7139382739481599406]
module.locust.data.aws_subnet.current: Read complete after 1s [id=subnet-****]
module.locust.data.aws_vpc.current: Reading...
module.locust.data.aws_vpc.current: Read complete after 0s [id=vpc-****]
module.locust.aws_security_group.loadtest: Refreshing state... [id=sg-0cc7e185d0b6035e6]
module.locust.aws_iam_instance_profile.loadtest: Refreshing state... [id=locuster-dist-loadtest-profile]
module.locust.data.aws_ami.amazon_linux_2: Read complete after 3s [id=ami-0d08ef957f0e4722b]
module.locust.aws_instance.nodes[3]: Refreshing state... [id=i-0dcf1bab9c079d17d]
module.locust.aws_instance.nodes[2]: Refreshing state... [id=i-0e9a8ccbe930343a8]
module.locust.aws_instance.nodes[0]: Refreshing state... [id=i-0cc320e0c6964a3d4]
module.locust.aws_instance.nodes[1]: Refreshing state... [id=i-0500f93dc3e480a58]
module.locust.aws_instance.leader: Refreshing state... [id=i-01069a4aa417686e4]
module.locust.null_resource.spliter_execute_command: Refreshing state... [id=4082036881688020582]
module.locust.null_resource.setup_leader: Refreshing state... [id=6433090945558305086]
module.locust.null_resource.setup_nodes[2]: Refreshing state... [id=7349787731921181745]
module.locust.null_resource.setup_nodes[0]: Refreshing state... [id=4438619351419084083]
module.locust.null_resource.setup_nodes[1]: Refreshing state... [id=87202048137344834]
module.locust.null_resource.setup_nodes[3]: Refreshing state... [id=462707723291235854]
module.locust.null_resource.executor[0]: Refreshing state... [id=1416692590300092713]
╷
│ Error: Cycle: module.locust.null_resource.setup_nodes[2] (destroy), module.locust.null_resource.setup_nodes[0] (destroy), module.locust.null_resource.setup_nodes[3] (destroy), module.locust.null_resource.executor[0] (destroy), module.locust.null_resource.setup_nodes[1] (destroy)
│
│
╵
Releasing state lock. This may take a few moments...

Proposal

• Change the dependency between null_resource.executor and null_resource.setup_nodes.
  As Locust requires to launch a master node first, and then workers to register recognized workers only. IMHO, the cycle would be solved with the dependency reverse, unless null_resource.setup_nodes has a critical reason that should be done before than null_resource.executor.
• poc: fix: reverse a dependency between null_resource.setup_nodes and `nu… #29