Tfgen does not respect fully computed on nested object properties

[VenelinMartinov]

What happened?

In pulumi/pulumi-gcp#2096 it was discovered that Computed + !Optional + !Required is not respected on nested object properties in tfgen.

The schemas is generated with the property as settable by the user:

  "gcp:compute/InstanceAttachedDisk:InstanceAttachedDisk": {
      "properties": {
          "deviceName": {
              "type": "string",
              "description": "Name with which the attached disk will be accessible\nunder `/dev/disk/by-id/google-*`\n"
          },
          "diskEncryptionKeyRaw": {
              "type": "string",
              "description": "A 256-bit [customer-supplied encryption key]\n(https://cloud.google.com/compute/docs/disks/customer-supplied-encryption),\nencoded in [RFC 4648 base64](https://tools.ietf.org/html/rfc4648#section-4)\nto encrypt this disk. Only one of `kms_key_self_link` and `disk_encryption_key_raw` may be set.\n",
              "secret": true
          },
          "diskEncryptionKeySha256": {
              "type": "string",
              "description": "The [RFC 4648 base64](https://tools.ietf.org/html/rfc4648#section-4)\nencoded SHA-256 hash of the [customer-supplied encryption key]\n(https://cloud.google.com/compute/docs/disks/customer-supplied-encryption) that protects this resource.\n"
          },
          "kmsKeySelfLink": {
              "type": "string",
              "description": "The self_link of the encryption key that is\nstored in Google Cloud KMS to encrypt this disk. Only one of `kms_key_self_link`\nand `disk_encryption_key_raw` may be set.\n"
          },
          "mode": {
              "type": "string",
              "description": "Either \"READ_ONLY\" or \"READ_WRITE\", defaults to \"READ_WRITE\"\nIf you have a persistent disk with data that you want to share\nbetween multiple instances, detach it from any read-write instances and\nattach it to one or more instances in read-only mode.\n"
          },
          "source": {
              "type": "string",
              "description": "The name or self_link of the disk to attach to this instance.\n"
          }
      },
      "type": "object",
      "required": [
          "source"
      ],
      "language": {
          "nodejs": {
              "requiredOutputs": [
                  "deviceName",
                  "diskEncryptionKeySha256",
                  "kmsKeySelfLink",
                  "source"
              ]
          }
      }
  },

Example

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Output of pulumi about

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Additional context

No response

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[t0yv0]

That's a good find, probably would be breaking to roll this out but in a good way (emphasize at compile time that programs are doing something wrong). There is a chance from what I remember that TF would panic or otherwise fail at runtime if a user attempts to set these. If this is true, we can fix it without worrying about breaking program compilation because the programs that would be affected are already broken at runtime, just need good changelog discipline.

[VenelinMartinov]

Yeah, TF does panic at runtime if the user tries to set a fully computed property, so this change should be entirely safe to make.

The tricky bit here is that the types are shared between inputs and outputs currently, which is how we ended up with the Computed properties in the input types.

[t0yv0]

There's another instance in AWS that's indeed broken. Very high value fix, I think.

[VenelinMartinov]

related to #493

[VenelinMartinov]

Currently this is only possible to do if we specify different input and output types for the top-level properties containing the nested computed properties. That would be quite breaking for user programs. The reason for that is that nested properties in the schema do not allow specifying different inputs and outputs.

The SDKs, however, already seem to generate different classes for inputs and outptus, so extending the Schema to support that seems quite plausible. Opened pulumi/pulumi#19436