Smoke test and blocking deployments

Terrafrom support depends_on for modules since 0.14. But when you have mixed push/pull deployment process (like provisioning k8s resources with terraform - terraform push yaml and k8s apply those yaml during pull model ) you may need some kind of validation in your module to make it’s execution blocking.

Other case may be a smoke test when you want to validate your service running after deployment.

I found that running a blocking smoke test for each component it is the best testing strategy for Infrastructure as code. With such approach you gain fastest feedback on component failures and in conjunction with depends_on modules you won’t need to search root cause in dependent components.

Here are my example of such blocking module:

resource "helm_release" "elasticsearch" {
  name   = local.esValues.esName
  chart  = "${path.module}/elasticsearch"
  atomic = true
  values = [
    yamlencode(local.esValues)
  ]
}

resource "null_resource" "ansible_validate_resources" {
  triggers = {
    playbook_contents = md5(file("${path.module}/../../ansible/validate.yml"))
    helm_release      = helm_release.elasticsearch.id
  }
  provisioner "local-exec" {
    command = <<COMMAND
    cd ${path.module}/../../ansible &&\
    ansible-playbook validate.yml \
      -e 'ansible_python_interpreter=/usr/bin/python3'
COMMAND

    environment = merge(local.ansibleEnvs, {
      name       = local.esValues.esName
      kind       = "Elasticsearch"
      apiVersion = "elasticsearch.k8s.elastic.co/v1"
    })
  }
  depends_on = [
    helm_release.elasticsearch
  ]
}