How to get hostname of OVH Load Balancer created via nginx helm release

Terraform Providers
,
1

Hi everyone, I’d really appreciate some help on this one.

So, I’m creating an OVH Public Cloud Kubernetes cluster, which has gone great so far.

I have deployed a nginx-ingress-controller via the helm_release module:

resource "helm_release" "nginx_ingress" {
  name       = "ingress-nginx"
  namespace = "ingress-nginx"
  create_namespace = true

  repository = "https://kubernetes.github.io/ingress-nginx"
  chart      = "ingress-nginx"

  values = [var.helm.nginx-ingress.values]
}

As the service type is set to LoadBalancer this triggers OVH to create a load balancer for me, great! However, I’m struggling with how I’d extract that new load balancer’s hostname/IP address via terraform, as I’d then like to create DNS records that point to it.

I can get it manually via kubectl get service ingress-nginx-controller -n ingress-nginx -o jsonpath="{.status.loadBalancer.ingress[0].hostname}" but I can’t find a way to do it in terraform.

I have tried:

Any ideas?

Thanks!

2

So, I figured out a way to do this.

I used a null_resource coupled with a local-exec provisioner to dump the kubeconfig file to disk (slightly dirty I know).

I then I run a shell command via the Invicton-Labs/shell-resource/external module to get the lb service’s IP.

I then use another null_resource coupled with a local-exec provisioned to delete the kubeconfig from disk.

I then output the shall command’s stdout which should be the LB’s hostname.

resource "null_resource" "create_kubeconfig" {
  provisioner "local-exec" {
    command = "echo \"${module.k8s.kubeconfig_file}\" >> \"${path.module}/kubeconfig\" && chmod 0600 \"${path.module}/kubeconfig\""
  }
  depends_on = [
    module.k8s
  ]
}

module "k8s_lb_hostname_query" {
  source  = "Invicton-Labs/shell-resource/external"
  working_dir = path.module

  // The command to run on resource creation on Unix machines
  command_unix         = "kubectl --kubeconfig \"${path.module}/kubeconfig\" get service ingress-nginx-controller -n ingress-nginx -o jsonpath=\"{.status.loadBalancer.ingress[0].hostname}\""
  depends_on = [
    null_resource.create_kubeconfig,
    helm_release.nginx_ingress
  ]
}

resource "null_resource" "rm_kubeconfig" {
  provisioner "local-exec" {
    command = "rm -f \"${path.module}/kubeconfig\""
  }
  depends_on = [
    null_resource.create_kubeconfig,
    module.k8s_lb_hostname_query
  ]
}```

:)
3

A common alternative method is to not use Terraform at all to manage the DNS and instead use the External DNS application - GitHub - kubernetes-sigs/external-dns: Configure external DNS servers (AWS Route53, Google CloudDNS and others) for Kubernetes Ingresses and Services

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