basic draft to fix #106

internal/terraform/exec/exec.go

@@ -256,6 +256,11 @@ func writeAndClose(w io.WriteCloser, input []byte) (int, error) {
 	return n, nil
 }
 
+func (e *Executor) Init(ctx context.Context) error {
+	_, err := e.run(ctx, "init")
+	return err
+}
+
 func (e *Executor) Version(ctx context.Context) (string, error) {
 	out, err := e.run(ctx, "version")
 	if err != nil {

internal/terraform/rootmodule/root_module.go

@@ -278,6 +278,17 @@ func (rm *rootModule) discoverTerraformExecutor(ctx context.Context) error {
 	return nil
 }
 
+func (rm *rootModule) ExecuteTerraformInit(ctx context.Context) error {
+	if err := rm.discoverTerraformExecutor(ctx); err != nil {
+		return err
+	}
+	if rm.tfExec == nil {
+		return errors.New("no terraform executor - unable to init workspace")
+	}
+
+	return rm.tfExec.Init(ctx)
+}
+
 func (rm *rootModule) discoverTerraformVersion(ctx context.Context) error {
 	if rm.tfExec == nil {
 		return errors.New("no terraform executor - unable to read version")

internal/terraform/rootmodule/root_module_manager.go

@@ -100,6 +100,10 @@ func (rmm *rootModuleManager) SetLogger(logger *log.Logger) {
 	rmm.logger = logger
 }
 
+func (rmm *rootModuleManager) NewPotentialRootModule(dir string) (RootModule, error) {
+	return rmm.newRootModule(context.Background(), filepath.Clean(dir))
+}
+
 func (rmm *rootModuleManager) AddAndStartLoadingRootModule(ctx context.Context, dir string) (RootModule, error) {
 	dir = filepath.Clean(dir)
 

internal/terraform/rootmodule/types.go

@@ -42,6 +42,7 @@ type RootModuleManager interface {
 	SetTerraformExecLogPath(logPath string)
 	SetTerraformExecTimeout(timeout time.Duration)
 
+	NewPotentialRootModule(dir string) (RootModule, error)
 	AddAndStartLoadingRootModule(ctx context.Context, dir string) (RootModule, error)
 	WorkerPoolSize() int
 	WorkerQueueSize() int
@@ -78,6 +79,7 @@ type RootModule interface {
 	IsParserLoaded() bool
 	TerraformFormatter() (exec.Formatter, error)
 	IsTerraformLoaded() bool
+	ExecuteTerraformInit(ctx context.Context) error
 	Modules() []ModuleRecord
 }
 

langserver/handlers/did_open.go

@@ -50,10 +50,34 @@ func (lh *logHandler) TextDocumentDidOpen(ctx context.Context, params lsp.DidOpe
 			// because we don't gather "init-able folders" in any way
 			" You may need to run terraform init"+
 			" and reload your editor.", readableDir)
-		return jrpc2.PushNotify(ctx, "window/showMessage", lsp.ShowMessageParams{
+		resp, _ := jrpc2.PushCall(ctx, "window/showMessageRequest", lsp.ShowMessageRequestParams{
 			Type:    lsp.MTWarning,
 			Message: msg,
+			Actions: []lsp.MessageActionItem{
+				{
+					Title: "run `terraform init`",
+				},
+			},
 		})
+		var action lsp.MessageActionItem
+		if err := resp.UnmarshalResult(&action); err != nil {
+			return err
+		}
+		if action.Title == "run `terraform init`" {
+			rmm, err := lsctx.RootModuleManager(ctx)
+			if err != nil {
+				return err
+			}
+			rm, err := rmm.NewPotentialRootModule(f.Dir())
+			if err != nil {
+				return err
+			}
+			go func() {
+				if err := rm.ExecuteTerraformInit(ctx); err != nil {
+					lh.logger.Printf("failed to execute `terraform init`: %+v", err)
+				}
+			}()
+		}
 	}
 	if len(candidates) > 1 {
 		candidateDir := humanReadablePath(rootDir, candidates[0].Path())

langserver/handlers/service.go

@@ -181,6 +181,7 @@ func (svc *service) Assigner() (jrpc2.Assigner, error) {
 			ctx = lsctx.WithDocumentStorage(ctx, fs)
 			ctx = lsctx.WithRootDirectory(ctx, &rootDir)
 			ctx = lsctx.WithRootModuleCandidateFinder(ctx, svc.modMgr)
+			ctx = lsctx.WithRootModuleManager(ctx, svc.modMgr)
 			ctx = lsctx.WithRootModuleWalker(ctx, svc.walker)
 			return handle(ctx, req, lh.TextDocumentDidOpen)
 		},