fix: add error detail for duplicate agent metadata key (#172)

* fix: add error detail for duplicate agent metadata key

* Update provider/agent.go

Co-authored-by: Mathias Fredriksson <[email protected]>

---------

Co-authored-by: Mathias Fredriksson <[email protected]>

Author: Kira-Pilot

provider/agent.go

@@ -11,6 +11,7 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/validation"
+	"golang.org/x/xerrors"
 )
 
 func agentResource() *schema.Resource {
@@ -38,6 +39,19 @@ func agentResource() *schema.Resource {
 					return diag.FromErr(err)
 				}
 			}
+
+			rawPlan := resourceData.GetRawPlan()
+			items := rawPlan.GetAttr("metadata").AsValueSlice()
+			itemKeys := map[string]struct{}{}
+			for _, item := range items {
+				key := valueAsString(item.GetAttr("key"))
+				_, exists := itemKeys[key]
+				if exists {
+					return diag.FromErr(xerrors.Errorf("duplicate agent metadata key %q", key))
+				}
+				itemKeys[key] = struct{}{}
+			}
+
 			return updateInitScript(resourceData, i)
 		},
 		ReadWithoutTimeout: func(ctx context.Context, resourceData *schema.ResourceData, i interface{}) diag.Diagnostics {

provider/agent_test.go

@@ -250,6 +250,42 @@ func TestAgent_Metadata(t *testing.T) {
 	})
 }
 
+func TestAgent_MetadataDuplicateKeys(t *testing.T) {
+	t.Parallel()
+	resource.Test(t, resource.TestCase{
+		Providers: map[string]*schema.Provider{
+			"coder": provider.New(),
+		},
+		IsUnitTest: true,
+		Steps: []resource.TestStep{{
+			Config: `
+				provider "coder" {
+					url = "https://example.com"
+				}
+				resource "coder_agent" "dev" {
+					os = "linux"
+					arch = "amd64"
+					metadata {
+						key = "process_count"
+						display_name = "Process Count"
+						script = "ps aux | wc -l"
+						interval = 5
+						timeout = 1
+					}
+					metadata {
+						key = "process_count"
+						display_name = "Process Count"
+						script = "ps aux | wc -l"
+						interval = 5
+						timeout = 1
+					}
+				}
+				`,
+			ExpectError: regexp.MustCompile("duplicate agent metadata key"),
+		}},
+	})
+}
+
 func TestAgent_DisplayApps(t *testing.T) {
 	t.Parallel()
 	t.Run("OK", func(t *testing.T) {