Bugfix: "400 Custom domains are not available for GitHub Pages []" when trying to update GH pages settings for a repository in GHES

github/config.go

@@ -35,6 +35,7 @@ type Owner struct {
 	v3client       *github.Client
 	v4client       *githubv4.Client
 	StopContext    context.Context
+	IsGHES         bool
 	IsOrganization bool
 }
 
@@ -164,6 +165,7 @@ func (c *Config) Meta() (any, error) {
 	owner.v4client = v4client
 	owner.v3client = v3client
 	owner.StopContext = context.Background()
+	owner.IsGHES = c.IsGHES
 
 	_, err = c.ConfigureOwner(&owner)
 	if err != nil {

github/resource_github_repository.go

@@ -978,7 +978,12 @@ func resourceGithubRepositoryUpdate(ctx context.Context, d *schema.ResourceData,
 			if pages == nil {
 				_, _, err = client.Repositories.EnablePages(ctx, owner, repoName, &github.Pages{Source: opts.Source, BuildType: opts.BuildType})
 			} else {
-				_, err = client.Repositories.UpdatePages(ctx, owner, repoName, opts)
+				if meta.(*Owner).IsGHES {
+					ghesOpts := updatePagesWithoutCNAME(opts)
+					_, err = client.Repositories.UpdatePagesGHES(ctx, owner, repoName, ghesOpts)
+				} else {
+					_, err = client.Repositories.UpdatePages(ctx, owner, repoName, opts)
+				}
 			}
 			if err != nil {
 				return diag.FromErr(err)
@@ -1129,6 +1134,19 @@ func expandPagesUpdate(input []any) *github.PagesUpdate {
 	return update
 }
 
+func updatePagesWithoutCNAME(update *github.PagesUpdate) *github.PagesUpdateWithoutCNAME {
+	if update == nil {
+		return nil
+	}
+
+	return &github.PagesUpdateWithoutCNAME{
+		BuildType:     update.BuildType,
+		Source:        update.Source,
+		Public:        update.Public,
+		HTTPSEnforced: update.HTTPSEnforced,
+	}
+}
+
 func flattenPages(pages *github.Pages) []any {
 	if pages == nil {
 		return []any{}

github/resource_github_repository_test.go

@@ -953,6 +953,64 @@ resource "github_repository" "test" {
 		})
 	})
 
+	t.Run("updates repository pages from legacy to workflow", func(t *testing.T) {
+		randomID := acctest.RandStringFromCharSet(5, acctest.CharSetAlphaNum)
+		testRepoName := fmt.Sprintf("%spages-2087-%s", testResourcePrefix, randomID)
+		testVisibility := "private"
+		if testAccConf.authMode == individual {
+			testVisibility = "public"
+		}
+
+		configs := map[string]string{
+			"legacy": fmt.Sprintf(`
+				resource "github_repository" "test" {
+					name       = "%s"
+					visibility = "%s"
+					auto_init  = true
+
+					pages {
+						build_type = "legacy"
+
+						source {
+							branch = "main"
+							path   = "/"
+						}
+					}
+				}
+			`, testRepoName, testVisibility),
+			"workflow": fmt.Sprintf(`
+				resource "github_repository" "test" {
+					name       = "%s"
+					visibility = "%s"
+					auto_init  = true
+
+					pages {
+						build_type = "workflow"
+					}
+				}
+			`, testRepoName, testVisibility),
+		}
+
+		resource.Test(t, resource.TestCase{
+			ProviderFactories: providerFactories,
+			Steps: []resource.TestStep{
+				{
+					Config: configs["legacy"],
+					Check: resource.ComposeTestCheckFunc(
+						resource.TestCheckResourceAttr("github_repository.test", "pages.0.source.0.branch", "main"),
+						resource.TestCheckResourceAttr("github_repository.test", "pages.0.source.0.path", "/"),
+					),
+				},
+				{
+					Config: configs["workflow"],
+					Check: resource.ComposeTestCheckFunc(
+						resource.TestCheckNoResourceAttr("github_repository.test", "pages.0.source.#"),
+					),
+				},
+			},
+		})
+	})
+
 	t.Run("manages the security feature for a private repository", func(t *testing.T) {
 		if !testAccConf.testAdvancedSecurity {
 			t.Skip("Advanced Security is not enabled for this account")