Better logging of state parsing errors

[silvpol]

I have come across an issue when cluster was upgraded from 1.15 to 1.16 and the config stopped working. I have updated the TF files to match the new format but plan keeps failing with a rather unhelpful message:

Error: missing expected [

Enabling Terraform TRACE logging didn't yield any clues and the only way I could spot the issue was to create another environment and compare state files.

I don't think there is a solution to migrate spec format here but a more detailed message with parsing error and some context would have allowed to pinpoint issue much quicker.

I'm using:

Terraform version: 0.12.20
terraform-provider-k8s_v0.1.4
Kubernetes 1.15 / 1.16

Resource in 1.15:

resource "k8s_cloud_google_com_v1beta1_backend_config" "www" {

  metadata {
    name      = "www"
    namespace = var.namespace
  }

  spec = jsonencode({
    timeoutSec = 600
  spec {
    timeout_sec = 600

    connectionDraining = {
      drainingTimeoutSec = 121
    connection_draining {
      draining_timeout_sec = 121
    }

    cdn = {
    cdn {
      enabled = true

      cachePolicy = {
        includeHost        = true
        includeProtocol    = true
        includeQueryString = true
      cache_policy {
        include_host         = true
        include_protocol     = true
        include_query_string = true
      }
    }
  })
  }
}

Same resource in 1.16:

resource "k8s_cloud_google_com_v1beta1_backend_config" "www" {

  metadata {
    name      = "www"
    namespace = var.namespace
  }

  spec {
    timeout_sec = 600

    connection_draining {
      draining_timeout_sec = 121
    }

    cdn {
      enabled = true

      cache_policy {
        include_host         = true
        include_protocol     = true
        include_query_string = true
      }
    }
  }
}

State fragment in 1.15:

    {
      "mode": "managed",
      "type": "k8s_cloud_google_com_v1beta1_backend_config",
      "name": "www",
      "provider": "provider.k8s",
      "instances": [
        {
          "schema_version": 0,
          "attributes": {
            "id": "test.backend_config.www",
            "metadata": [
              {
                "annotations": {},
                "creation_timestamp": "2020-03-31T08:32:16Z",
                "deletion_grace_period_seconds": 0,
                "deletion_timestamp": "",
                "labels": {},
                "name": "www",
                "namespace": "test",
                "resource_version": "8569",
                "self_link": "/apis/cloud.google.com/v1beta1/namespaces/test/backendconfigs/www",
                "uid": "39592fd1-83b7-48ac-af98-9497c4a5c9dc"
              }
            ],
            "spec": "{\"cdn\":{\"cachePolicy\":{\"includeHost\":true,\"includeProtocol\":true,\"includeQueryString\":true},\"enabled\":true},\"connectionDraining\":{\"drainingTimeoutSec\":121},\"timeoutSec\":600}"
          },
          "private": "bnVsbA=="
        }
      ]
    },

State fragment in 1.16:

    {
      "mode": "managed",
      "type": "k8s_cloud_google_com_v1beta1_backend_config",
      "name": "www",
      "provider": "provider.k8s",
      "instances": [
        {
          "schema_version": 0,
          "attributes": {
            "id": "kube.backend_config.www",
            "metadata": [
              {
                "annotations": {},
                "creation_timestamp": "2020-10-26T20:05:01Z",
                "deletion_grace_period_seconds": 0,
                "deletion_timestamp": "",
                "labels": {},
                "name": "www",
                "namespace": "kube",
                "resource_version": "100795599",
                "self_link": "/apis/cloud.google.com/v1beta1/namespaces/kube/backendconfigs/www",
                "uid": "87c19eed-6aae-4cb9-a86a-1dae1b319bb4"
              }
            ],
            "spec": [
              {
                "cdn": [
                  {
                    "cache_policy": [
                      {
                        "include_host": "true",
                        "include_protocol": "true",
                        "include_query_string": "true",
                        "query_string_blacklist": [],
                        "query_string_whitelist": []
                      }
                    ],
                    "enabled": "true"
                  }
                ],
                "connection_draining": [
                  {
                    "draining_timeout_sec": 121
                  }
                ],
                "custom_request_headers": [],
                "health_check": [],
                "iap": [],
                "logging": [],
                "security_policy": [],
                "session_affinity": [],
                "timeout_sec": 600
              }
            ]
          },
          "private": "bnVsbA=="
        }
      ]
    },