From 48d64eabb24fcf632d2ea74411203097e5e4f6a4 Mon Sep 17 00:00:00 2001
From: Alisdair McDiarmid <alisdair@users.noreply.github.com>
Date: Mon, 13 Jun 2022 13:56:50 -0400
Subject: [PATCH] json-output: Extended detail for unknown outputs

Planned output changes are represented in the JSON output format using
the same change object as planned resource changes. This structure
includes an `after` value and a parallel `after_unknown` value, which
can be combined to determine which specific parts of a value are known
only at apply time.

Previously, structured output values would be marked in the JSON plan as
coarsely known or unknown, even if only some subset of the structure
will be known only at apply time. This simplification was unnecessary,
and this commit reuses the same logic for resource changes to give more
information to consumers of this format.

For example, consider this output:

    output "bar" {
      value = tolist([
        "hello",
        timestamp(),
        "world",
      ])
    }

The plan output for this output would be:

    + bar = [
        + "hello",
        + (known after apply),
        + "world",
      ]

For the same plan, the JSON output was previously:

    "bar": {
      "actions": [
        "create"
      ],
      "before": null,
      "after_unknown": true,
      "before_sensitive": false,
      "after_sensitive": false
    }

After this commit, the output is instead:

    "bar": {
      "actions": [
        "create"
      ],
      "before": null,
      "after": [
        "hello",
        null,
        "world"
      ],
      "after_unknown": [
        false,
        true,
        false
      ],
      "before_sensitive": false,
      "after_sensitive": false
    }
---
 internal/command/jsonplan/plan.go             | 15 ++-
 .../testdata/show-json/unknown-output/main.tf | 19 ++++
 .../show-json/unknown-output/output.json      | 96 +++++++++++++++++++
 3 files changed, 128 insertions(+), 2 deletions(-)
 create mode 100644 internal/command/testdata/show-json/unknown-output/main.tf
 create mode 100644 internal/command/testdata/show-json/unknown-output/output.json

diff --git a/internal/command/jsonplan/plan.go b/internal/command/jsonplan/plan.go
index 0a4f9bcd6e..b8ff13676b 100644
--- a/internal/command/jsonplan/plan.go
+++ b/internal/command/jsonplan/plan.go
@@ -442,7 +442,8 @@ func (p *plan) marshalOutputChanges(changes *plans.Changes) error {
 		changeV.After, _ = changeV.After.UnmarkDeep()
 
 		var before, after []byte
-		afterUnknown := cty.False
+		var afterUnknown cty.Value
+
 		if changeV.Before != cty.NilVal {
 			before, err = ctyjson.Marshal(changeV.Before, changeV.Before.Type())
 			if err != nil {
@@ -455,8 +456,18 @@ func (p *plan) marshalOutputChanges(changes *plans.Changes) error {
 				if err != nil {
 					return err
 				}
+				afterUnknown = cty.False
 			} else {
-				afterUnknown = cty.True
+				filteredAfter := omitUnknowns(changeV.After)
+				if filteredAfter.IsNull() {
+					after = nil
+				} else {
+					after, err = ctyjson.Marshal(filteredAfter, filteredAfter.Type())
+					if err != nil {
+						return err
+					}
+				}
+				afterUnknown = unknownAsBool(changeV.After)
 			}
 		}
 
diff --git a/internal/command/testdata/show-json/unknown-output/main.tf b/internal/command/testdata/show-json/unknown-output/main.tf
new file mode 100644
index 0000000000..d97891e224
--- /dev/null
+++ b/internal/command/testdata/show-json/unknown-output/main.tf
@@ -0,0 +1,19 @@
+output "foo" {
+  value = "hello"
+}
+
+output "bar" {
+  value = tolist([
+    "hello",
+    timestamp(),
+    "world",
+  ])
+}
+
+output "baz" {
+  value = {
+    greeting: "hello",
+    time: timestamp(),
+    subject: "world",
+  }
+}
diff --git a/internal/command/testdata/show-json/unknown-output/output.json b/internal/command/testdata/show-json/unknown-output/output.json
new file mode 100644
index 0000000000..8a52b8dc57
--- /dev/null
+++ b/internal/command/testdata/show-json/unknown-output/output.json
@@ -0,0 +1,96 @@
+{
+  "format_version": "1.1",
+  "terraform_version": "1.3.0-dev",
+  "planned_values": {
+    "outputs": {
+      "bar": {
+        "sensitive": false
+      },
+      "baz": {
+        "sensitive": false
+      },
+      "foo": {
+        "sensitive": false,
+        "type": "string",
+        "value": "hello"
+      }
+    },
+    "root_module": {}
+  },
+  "output_changes": {
+    "bar": {
+      "actions": [
+        "create"
+      ],
+      "before": null,
+      "after": [
+        "hello",
+        null,
+        "world"
+      ],
+      "after_unknown": [
+        false,
+        true,
+        false
+      ],
+      "before_sensitive": false,
+      "after_sensitive": false
+    },
+    "baz": {
+      "actions": [
+        "create"
+      ],
+      "before": null,
+      "after": {
+        "greeting": "hello",
+        "subject": "world"
+      },
+      "after_unknown": {
+        "time": true
+      },
+      "before_sensitive": false,
+      "after_sensitive": false
+    },
+    "foo": {
+      "actions": [
+        "create"
+      ],
+      "before": null,
+      "after": "hello",
+      "after_unknown": false,
+      "before_sensitive": false,
+      "after_sensitive": false
+    }
+  },
+  "prior_state": {
+    "format_version": "1.0",
+    "terraform_version": "1.3.0",
+    "values": {
+      "outputs": {
+        "foo": {
+          "sensitive": false,
+          "value": "hello",
+          "type": "string"
+        }
+      },
+      "root_module": {}
+    }
+  },
+  "configuration": {
+    "root_module": {
+      "outputs": {
+        "bar": {
+          "expression": {}
+        },
+        "baz": {
+          "expression": {}
+        },
+        "foo": {
+          "expression": {
+            "constant_value": "hello"
+          }
+        }
+      }
+    }
+  }
+}