fix: handle user deletion config drift (#209)

Closes #208.

Querying `api/v2/users/{ID}` returns a valid response for deleted users, as deleted users in `coderd` are merely tombstoned. To handle this, we perform an additional query by username. If the user has been deleted, the username will be available, or belong to a user with a different ID, in which case we can mark the user resource as deleted.

Also has the `isNotFound` check include the specific response for when a user does not exist:
```
sdkErr.StatusCode() == http.StatusBadRequest && strings.Contains(sdkErr.Message, "must be an existing uuid or username")
```

Author: ethanndickson

internal/provider/user_resource.go

@@ -248,14 +248,15 @@ func (r *UserResource) Read(ctx context.Context, req resource.ReadRequest, resp
 
 	client := r.data.Client
 
+	// Lookup by ID to handle imports
 	user, err := client.User(ctx, data.ID.ValueString())
 	if err != nil {
 		if isNotFound(err) {
-			resp.Diagnostics.AddWarning("Client Warning", fmt.Sprintf("User with ID %q not found. Marking as deleted.", data.ID.ValueString()))
+			resp.Diagnostics.AddWarning("Client Warning", fmt.Sprintf("User with ID %q not found. Marking resource as deleted.", data.ID.ValueString()))
 			resp.State.RemoveResource(ctx)
 			return
 		}
-		resp.Diagnostics.AddError("Client Error", fmt.Sprintf("Unable to get current user, got error: %s", err))
+		resp.Diagnostics.AddError("Client Error", fmt.Sprintf("Unable to get current user by ID, got error: %s", err))
 		return
 	}
 	if len(user.OrganizationIDs) < 1 {
@@ -274,6 +275,30 @@ func (r *UserResource) Read(ctx context.Context, req resource.ReadRequest, resp
 	data.LoginType = types.StringValue(string(user.LoginType))
 	data.Suspended = types.BoolValue(user.Status == codersdk.UserStatusSuspended)
 
+	// The user-by-ID API returns deleted users if the authorized user has
+	// permission. It does not indicate whether the user is deleted or not.
+	// The user-by-username API will never return deleted users.
+	// So, we do another lookup by username.
+	userByName, err := client.User(ctx, data.Username.ValueString())
+	if err != nil {
+		if isNotFound(err) {
+			resp.Diagnostics.AddWarning("Client Warning", fmt.Sprintf(
+				"User with username %q not found. Marking resource as deleted.",
+				data.Username.ValueString()))
+			resp.State.RemoveResource(ctx)
+			return
+		}
+		resp.Diagnostics.AddError("Client Error", fmt.Sprintf("Unable to get current user by username, got error: %s", err))
+		return
+	}
+	if userByName.ID != data.ID.ValueUUID() {
+		resp.Diagnostics.AddWarning("Client Error", fmt.Sprintf(
+			"The username %q has been reassigned to a new user not managed by this Terraform resource. Marking resource as deleted.",
+			user.Username))
+		resp.State.RemoveResource(ctx)
+		return
+	}
+
 	// Save updated data into Terraform state
 	resp.Diagnostics.Append(resp.State.Set(ctx, &data)...)
 }

internal/provider/user_resource_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/coder/coder/v2/coderd/util/ptr"
 	"github.com/coder/terraform-provider-coderd/integration"
 	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
 	"github.com/stretchr/testify/require"
 )
 
@@ -100,6 +101,19 @@ func TestAccUserResource(t *testing.T) {
 					resource.TestCheckResourceAttr("coderd_user.test", "login_type", "github"),
 				),
 			},
+			// Verify config drift via deletion is handled
+			{
+				Config: cfg4.String(t),
+				Check: func(*terraform.State) error {
+					user, err := client.User(ctx, "exampleNew")
+					if err != nil {
+						return err
+					}
+					return client.DeleteUser(ctx, user.ID)
+				},
+				// The Plan should be to create the entire resource
+				ExpectNonEmptyPlan: true,
+			},
 		},
 	})
 }

internal/provider/util.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/coder/coder/v2/codersdk"
 	"github.com/google/uuid"
@@ -110,5 +111,15 @@ func memberDiff(currentMembers []uuid.UUID, plannedMembers []UUID) (add, remove
 
 func isNotFound(err error) bool {
 	var sdkErr *codersdk.Error
-	return errors.As(err, &sdkErr) && sdkErr.StatusCode() == http.StatusNotFound
+	if !errors.As(err, &sdkErr) {
+		return false
+	}
+	if sdkErr.StatusCode() == http.StatusNotFound {
+		return true
+	}
+	// `httpmw/ExtractUserContext` returns a 400 w/ this message if the user is not found
+	if sdkErr.StatusCode() == http.StatusBadRequest && strings.Contains(sdkErr.Message, "must be an existing uuid or username") {
+		return true
+	}
+	return false
 }