How to make Terraform continue with execution and ignore an error with resource creation during terraform apply?

Question

I am installing CNI using null_resource in terraform. Now if the CNI is already installed the terraform script fails with error: exit status 254. Output: │ An error occurred (ResourceInUseException) when calling the CreateAddon │ operation: Addon already exists. How can I make terraform continue with execution if the CNI is already installed, rather than failing.

Below is my Configuration for installing CNI:

### Installing CNI Addon ###
resource "null_resource" "install-CNI" {
  provisioner "local-exec" {
    when = create
    interpreter = ["bash", "-c"]
    command = <<EOT
        aws eks create-addon  \
            --cluster-name ${data.aws_eks_cluster.Custom_Dev-cluster-deploy.name} \
            --addon-name vpc-cni \
            --addon-version v1.11.2-eksbuild.1 \
            --service-account-role-arn ${aws_iam_role.Custom_Dev-cluster.arn} \
            --resolve-conflicts OVERWRITE
    EOT
  }
  triggers = {
    "before" = null_resource.eks-config-file.id
  }
}

Answer 1

you can handle the error base on the response. if the command response contains Addon already exists you can exit 0 and return an error if something else, it can be aws cli permission or wrong command.

resource "null_resource" "install-CNI" {
  provisioner "local-exec" {
    when = create
    interpreter = ["bash", "-c"]
    command = <<EOT
        RESULT=$(aws eks create-addon --cluster-name ${data.aws_eks_cluster.Custom_Dev-cluster-deploy.name} --addon-name vpc-cni --addon-version v1.11.2-eksbuild.1 --service-account-role-arn ${aws_iam_role.Custom_Dev-cluster.arn} --resolve-conflicts OVERWRITE 2>&1)
        if [ $? -eq 0 ]
        then
        echo "Addon installed successfully $RESULT"
        exit 0
        elif [[ "$RESULT" =~ .*"Addon already exists".* ]] 
        then
        echo "Plugin already exists $RESULT" >&2
        exit 0
        else 
        echo "Encounter error $RESULT" >&2
        exit 1
        fi
    EOT
    
  }
  triggers = {
    "before" = null_resource.eks-config-file.id
  }
}