resource/gitlab_project: fix backwards-compatibility with 14.1 regarding the squash_option. Closes #770

I gotta admit that I'm not support happy with the implementation,
nor the approach in general.

However, I think we agree that it's best to not break backwards
compatiblity as first priority.

In any case, we have #550 to discuss that :)

Closes #770
Closes #776

Author: timofurrer

docs/resources/project.md

@@ -78,7 +78,7 @@ resource "gitlab_project" "example-two" {
 - **request_access_enabled** (Boolean) Allow users to request member access.
 - **shared_runners_enabled** (Boolean) Enable shared runners for this project.
 - **snippets_enabled** (Boolean) Enable snippets for the project.
-- **squash_option** (String) Squash commits when merge request. Valid values are `never`, `always`, `default_on`, or `default_off`. The default value is `default_off`.
+- **squash_option** (String) Squash commits when merge request. Valid values are `never`, `always`, `default_on`, or `default_off`. The default value is `default_off`. [GitLab >= 14.1]
 - **tags** (Set of String) Tags (topics) of the project.
 - **template_name** (String) When used without use_custom_template, name of a built-in project template. When used with use_custom_template, name of a custom project template. This option is mutually exclusive with `template_project_id`.
 - **template_project_id** (Number) When used with use_custom_template, project ID of a custom project template. This is preferable to using template_name since template_name may be ambiguous (enterprise edition). This option is mutually exclusive with `template_name`.

internal/provider/resource_gitlab_project.go

@@ -193,7 +193,7 @@ var resourceGitLabProjectSchema = map[string]*schema.Schema{
 		Optional:    true,
 	},
 	"squash_option": {
-		Description:  "Squash commits when merge request. Valid values are `never`, `always`, `default_on`, or `default_off`. The default value is `default_off`.",
+		Description:  "Squash commits when merge request. Valid values are `never`, `always`, `default_on`, or `default_off`. The default value is `default_off`. [GitLab >= 14.1]",
 		Type:         schema.TypeString,
 		Optional:     true,
 		Default:      "default_off",
@@ -386,7 +386,7 @@ var _ = registerResource("gitlab_project", func() *schema.Resource {
 	}
 })
 
-func resourceGitlabProjectSetToState(d *schema.ResourceData, project *gitlab.Project) error {
+func resourceGitlabProjectSetToState(client *gitlab.Client, d *schema.ResourceData, project *gitlab.Project) error {
 	d.SetId(fmt.Sprintf("%d", project.ID))
 	d.Set("name", project.Name)
 	d.Set("path", project.Path)
@@ -417,7 +417,11 @@ func resourceGitlabProjectSetToState(d *schema.ResourceData, project *gitlab.Pro
 		return err
 	}
 	d.Set("archived", project.Archived)
-	d.Set("squash_option", project.SquashOption)
+	if supportsSquashOption, err := isGitLabVersionAtLeast(client, "14.1")(); err != nil {
+		return err
+	} else if supportsSquashOption {
+		d.Set("squash_option", project.SquashOption)
+	}
 	d.Set("remove_source_branch_after_merge", project.RemoveSourceBranchAfterMerge)
 	d.Set("packages_enabled", project.PackagesEnabled)
 	d.Set("pages_access_level", string(project.PagesAccessLevel))
@@ -453,7 +457,6 @@ func resourceGitlabProjectCreate(ctx context.Context, d *schema.ResourceData, me
 		OnlyAllowMergeIfAllDiscussionsAreResolved: gitlab.Bool(d.Get("only_allow_merge_if_all_discussions_are_resolved").(bool)),
 		AllowMergeOnSkippedPipeline:               gitlab.Bool(d.Get("allow_merge_on_skipped_pipeline").(bool)),
 		SharedRunnersEnabled:                      gitlab.Bool(d.Get("shared_runners_enabled").(bool)),
-		SquashOption:                              stringToSquashOptionValue(d.Get("squash_option").(string)),
 		RemoveSourceBranchAfterMerge:              gitlab.Bool(d.Get("remove_source_branch_after_merge").(bool)),
 		PackagesEnabled:                           gitlab.Bool(d.Get("packages_enabled").(bool)),
 		Mirror:                                    gitlab.Bool(d.Get("mirror").(bool)),
@@ -515,6 +518,14 @@ func resourceGitlabProjectCreate(ctx context.Context, d *schema.ResourceData, me
 		options.CIConfigPath = gitlab.String(v.(string))
 	}
 
+	if supportsSquashOption, err := isGitLabVersionAtLeast(client, "14.1")(); err != nil {
+		return diag.FromErr(err)
+	} else if supportsSquashOption {
+		if v, ok := d.GetOk("squash_option"); ok {
+			options.SquashOption = stringToSquashOptionValue(v.(string))
+		}
+	}
+
 	log.Printf("[DEBUG] create gitlab project %q", *options.Name)
 
 	project, _, err := client.Projects.CreateProject(options, gitlab.WithContext(ctx))
@@ -672,7 +683,7 @@ func resourceGitlabProjectRead(ctx context.Context, d *schema.ResourceData, meta
 		return nil
 	}
 
-	if err := resourceGitlabProjectSetToState(d, project); err != nil {
+	if err := resourceGitlabProjectSetToState(client, d, project); err != nil {
 		return diag.FromErr(err)
 	}
 
@@ -782,7 +793,9 @@ func resourceGitlabProjectUpdate(ctx context.Context, d *schema.ResourceData, me
 		options.LFSEnabled = gitlab.Bool(d.Get("lfs_enabled").(bool))
 	}
 
-	if d.HasChange("squash_option") {
+	if supportsSquashOption, err := isGitLabVersionAtLeast(client, "14.1")(); err != nil {
+		return diag.FromErr(err)
+	} else if supportsSquashOption && d.HasChange("squash_option") {
 		options.SquashOption = stringToSquashOptionValue(d.Get("squash_option").(string))
 	}
 

internal/provider/resource_gitlab_project_test.go

@@ -964,11 +964,11 @@ func testAccCheckAggregateGitlabProject(expected, received *gitlab.Project) reso
 				}
 			}
 
-			if err := resourceGitlabProjectSetToState(expectedData, expected); err != nil {
+			if err := resourceGitlabProjectSetToState(testGitlabClient, expectedData, expected); err != nil {
 				return err
 			}
 
-			if err := resourceGitlabProjectSetToState(receivedData, received); err != nil {
+			if err := resourceGitlabProjectSetToState(testGitlabClient, receivedData, received); err != nil {
 				return err
 			}