# Trigger local exec when resources changes

**URL:** <https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789>\
**Category:** Terraform\
**Created:** [September 4, 2020, 1:11pm UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789 "2020-09-04T13:11:35Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![linuxbsdfreak](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/linuxbsdfreak/32/9430_2.png) [@linuxbsdfreak](https://discuss.hashicorp.com/u/linuxbsdfreak)\
**Post date:** [September 4, 2020, 1:11pm UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/1 "2020-09-04T13:11:35Z")

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Hi @apparentlymart ,

Apologizes for asking TF Qs. Learning new stuff everyday 🙂

I have the following snippet for example which is a K8s Custom Resource

```auto
terraform {
  required_version = ">= 0.13.0"
  required_providers {
    kubectl = {
      source = "github.com/gavinbunney/kubectl"
      version = "1.5.1"
    }
  }
}

provider "kubectl" {
  config_path = "/tmp/configs/my.kubeconfig"
  load_config_file = true
}

resource "kubectl_manifest" "gardener_shoot" {
   yaml_body = templatefile("${path.module}/templates/gardener-shoot.yaml.tmpl", {
          shoot_cluster_name = var.shoot_cluster_name,
          project_name = var.project_name,
          create_timeout = var.create_timeout,
          update_timeout = var.update_timeout,
          delete_timeout = var.delete_timeout,
          dashboard_enabled = var.dashboard_enabled,
          nginx_enabled = var.nginx_enabled,
          target_profile = var.target_profile,
          kubernetes_version = var.kubernetes_version,
          maintenance_k8s_version_enabled = var.maintenance_k8s_version_enabled,
          maintenance_machine_image_version_enabled = var.maintenance_machine_image_version_enabled,
          networking_nodes = var.networking_nodes,
          networking_pods = var.networking_pods,
          networking_services = var.networking_services,
          networking_type = var.networking_type,
          vnetcidr = var.vnetcidr,
          cloud_provider = var.cloud_provider,
          machine_image_name = var.machine_image_name,
          machine_image_version = var.machine_image_version,
          machine_type = var.machine_type,
          worker_max_surge = var.worker_max_surge,
          worker_max_unavailable = var.worker_max_unavailable,
          worker_maximum = var.worker_maximum,
          worker_minimum = var.worker_minimum,
          worker_name = var.worker_name,
          disk_size = var.disk_size,
          disk_type = var.disk_type,
          location = var.location,
          target_secret = var.target_secret,
          zones = var.zones,
          subnets = var.subnets,
        })
}

resource "null_resource" "check_shoot_status" {
  provisioner "local-exec" {
    command = "/tmp/shoot-status"
  }
  depends_on = [kubectl_manifest.gardener_shoot]
}

```

To check the status of the K8s resource creation. I created a binary to check the status which works on initial run. How do i trigger the null\_resource when the resource changes ?

Kevin

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<div class="post-metadata">

**Author:** ![vasylenko](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/vasylenko/32/27614_2.png) [@vasylenko](https://discuss.hashicorp.com/u/vasylenko)\
**Post date:** [September 6, 2020, 12:44am UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/2 "2020-09-06T00:44:23Z")

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> [@linuxbsdfreak](#):
>
> To check the status of the K8s resource creation. I created a binary to check the status which works on initial run. How do i trigger the null\_resource when the resource changes ?

It seems that you can achieve your goal with `triggers` argument. Here is the link to docs – [Terraform Registry](https://registry.terraform.io/providers/hashicorp/null/latest/docs/resources/resource)

---

<div class="post-metadata">

**Author:** ![linuxbsdfreak](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/linuxbsdfreak/32/9430_2.png) [@linuxbsdfreak](https://discuss.hashicorp.com/u/linuxbsdfreak)\
**Post date:** [September 7, 2020, 8:39am UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/3 "2020-09-07T08:39:09Z")

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Hi @vasylenko,

Thanks for the reply. I did the following

```auto
resource "null_resource" "check_shoot_status" {
  triggers = {
    //shoot_id = kubectl_manifest.gardener_shoot.id
    always_run = "${timestamp()}"
  }

  provisioner "local-exec" {
    command = "/tmp/shoot-status"
  }

  depends_on = [kubectl_manifest.gardener_shoot]
}

```

Which works well every time irrespective if the resource changes. However is there a way to trigger only when the resource changes or associate **shoot\_id** to the provisioner?

Kevin

---

<div class="post-metadata">

**Author:** ![vasylenko](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/vasylenko/32/27614_2.png) [@vasylenko](https://discuss.hashicorp.com/u/vasylenko)\
**Post date:** [September 8, 2020, 4:50pm UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/4 "2020-09-08T16:50:09Z")

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@linuxbsdfreak It looks that you already have the answer in your commented code

```auto
triggers {
  shoot_id = "${kubectl_manifest.gardener_shoot.id}"
}

```

This is exactly how you can map trigger to specific attribute of another resource (within a module scope of course).  
I am not sure what `shoot_id` is (and I could not find documentation for your provider online), but your idea is correct. So if the `kubectl_manifest` resource type of your provider does have the `id` attribute, then your trigger should work as expected: be triggered once the `id` attribute is changed.

---

<div class="post-metadata">

**Author:** ![linuxbsdfreak](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/linuxbsdfreak/32/9430_2.png) [@linuxbsdfreak](https://discuss.hashicorp.com/u/linuxbsdfreak)\
**Post date:** [September 8, 2020, 5:16pm UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/5 "2020-09-08T17:16:34Z")

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Hi @vasylenko,

Thanks for the feedback. I tried that however it did not work. I am only doing a kubectl apply with the kubectl provider from the [github.com](http://github.com) site. It detects the change. However it does not trigger the local-exec. Wondering what trigger value I need to set for the resource.

> **[kubectl\_manifest · Kubectl Terraform Provider](https://gavinbunney.github.io/terraform-provider-kubectl/docs/kubectl_manifest)**
>
> Create a Kubernetes resource using raw YAML manifests.

Kevin

---

<div class="post-metadata">

**Author:** ![vasylenko](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/vasylenko/32/27614_2.png) [@vasylenko](https://discuss.hashicorp.com/u/vasylenko)\
**Post date:** [September 13, 2020, 9:22pm UTC](https://discuss.hashicorp.com/t/trigger-local-exec-when-resources-changes/13789/6 "2020-09-13T21:22:56Z")

</div>

@linuxbsdfreak The main idea is that you need to reference a value that changes in order to make your trigger do its work. Perhaps `uid` or `live_uid` (found that in docs you provided). Unfortunately I’m not quite good with k8s yet, so I can’t say for sure from the provider point of view. But the trigger will work only if the value (you are referencing to) is changed.