Terraform Condition on Deployment

user_1971380 0
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I'm using terraform in deployment. I have a list of deployment and using for_each on deployment. Based on string condition I need to add a sidecar.

Briefly, I need to write a condition to add a sidecar image.

Something like it:

${substr(each.key, 0, 3) == "tst" ? 1 : 0 }

Is there a way to achieve that?

Here is my deployment tf:

resource "kubernetes_deployment" "x" {
  for_each = data
  metadata {
    name = each.key
    labels = {
      app = each.key
      name = each.key
    }
    namespace = var.namespace
  }
  spec {
    replicas = 1

    selector {
      match_labels = {
        app = each.key
      }
    }
    template {
      metadata {
        labels = {
          app = each.key
          name = each.key
        }
      }
      spec {
        service_account_name = "default"

        container {
          image = each.value
          image_pull_policy = "Always"
          name = each.key
        }
        // I need a condtion to create the second container
        container {
          image = "sidecar_image"
          image_pull_policy = "Always"
          name = "sidecar-container"
          port {
            name           = "default-port"
            container_port = 50050
          }
        }

        restart_policy = "Always"
      }
    }
  }
}
terraform
2 Answers

You could use a dynamic block for the second container block in order to make it conditional. For example, consider the following piece of code:

dynamic "container" {
    for_each          = var.is_test ? [1] : []
    image             = "sidecar_image"
    image_pull_policy = "Always"
    name              = "sidecar-container"
    port {
        name           = "default-port"
        container_port = 50050
    }
}

Note that the condition will require some more attention but I think this should be enough to get you started.

user_29259620

In general you can see the nuances around conditional nested blocks in this answer. To tailor this to your specific situation though:

dynamic "container" {
  for_each = range(substr(each.key, 0, 3) == "tst" ? 1 : 0)
 
  content {
    image = "sidecar_image"
    image_pull_policy = "Always"
    name = "sidecar-container"
    port {
      name           = "default-port"
      container_port = 50050
    }
  }
}

This assumes well-formed data keys in your for_each meta-argument value for the resource as provided in your question.

One immediate issue I note with your conditional is that the substring from index 0 to 3 will contain four values, and you are testing against a string with three characters. You probably wanted to do:

substr(each.key, 0, 2)

or perhaps also:

can(regex("^tst", each.key))

but either way your provided conditional will always return false.

user_53433870
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