How to fix Error creating SslCertificate: googleapi: Error 409: The resource already exists in Terraform

First, verify the certificate exists in GCP by checking Compute Engine > Security > SSL Certificates:

gcloud compute ssl-certificates list

This confirms whether the resource physically exists in GCP, separate from your Terraform state.

If the certificate is in use by a load balancer, it cannot be deleted or replaced directly. List what's using it:

gcloud compute target-https-proxies list
gcloud compute target-https-proxies describe [PROXY_NAME] --global

Note which proxies reference your certificate. This is the most common blocker.

If the certificate already exists in GCP and you want to manage it with Terraform, import it:

terraform import google_compute_ssl_certificate.my_cert [CERTIFICATE_NAME]

This adds the existing resource to your Terraform state without recreating it. Then update your Terraform code to match the actual resource.

If you need to replace the certificate, first update any target HTTPS proxies to use a temporary/migration certificate:

gcloud compute target-https-proxies update [PROXY_NAME] --ssl-certificates=[TEMP_CERT_NAME] --global

Then the old certificate can be deleted via Terraform, allowing the new one to be created.

For managed certificates where you can't modify domains, use a unique naming strategy with a suffix:

resource "random_id" "cert_suffix" {
  byte_length = 4
  keepers = {
    domains = join(",", var.domains)
  }
}

resource "google_compute_managed_ssl_certificate" "my_cert" {
  name = "my-cert-${random_id.cert_suffix.hex}"
  managed {
    domains = var.domains
  }

  lifecycle {
    create_before_destroy = true
  }
}

This generates unique names to avoid conflicts when domains change.

As a last resort, manually delete the certificate if nothing references it:

gcloud compute ssl-certificates delete [CERTIFICATE_NAME]

Then run:

terraform apply

WARNING: Only do this if you've confirmed nothing is using the certificate, or you'll break production load balancers.