From 97bde5467c8ff8f791e0556fe809b2d8bf11f511 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Tue, 2 Apr 2019 14:27:31 -0400
Subject: [PATCH] filter nulls when shimming a config

Nulls can't exist in HCL, and the legacy sdk will panic when
encountering them. The map shim already did this, just copy the same
pattern in the list case.
---
 config/hcl2shim/values.go      |  5 ++++-
 config/hcl2shim/values_test.go | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/config/hcl2shim/values.go b/config/hcl2shim/values.go
index 2c5b2907e..b5868f6ed 100644
--- a/config/hcl2shim/values.go
+++ b/config/hcl2shim/values.go
@@ -167,7 +167,10 @@ func ConfigValueFromHCL2(v cty.Value) interface{} {
 		it := v.ElementIterator()
 		for it.Next() {
 			_, ev := it.Element()
-			l = append(l, ConfigValueFromHCL2(ev))
+			cv := ConfigValueFromHCL2(ev)
+			if cv != nil {
+				l = append(l, cv)
+			}
 		}
 		return l
 	}
diff --git a/config/hcl2shim/values_test.go b/config/hcl2shim/values_test.go
index 7c3011da0..ac70c339e 100644
--- a/config/hcl2shim/values_test.go
+++ b/config/hcl2shim/values_test.go
@@ -232,6 +232,26 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 			&configschema.Block{},
 			nil,
 		},
+		// nulls should be filtered out of the config, since they couldn't exist
+		// in hcl.
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"list": cty.ListVal([]cty.Value{
+					cty.StringVal("ok"),
+					cty.NullVal(cty.String)}),
+			}),
+			&configschema.Block{
+				Attributes: map[string]*configschema.Attribute{
+					"list": {
+						Type:     cty.List(cty.String),
+						Optional: true,
+					},
+				},
+			},
+			map[string]interface{}{
+				"list": []interface{}{"ok"},
+			},
+		},
 	}
 
 	for _, test := range tests {