settings: Make root modules configurable

go.mod

@@ -7,12 +7,13 @@ require (
 	github.com/creachadair/jrpc2 v0.8.1
 	github.com/fsnotify/fsnotify v1.4.9
 	github.com/google/go-cmp v0.4.0
-	github.com/hashicorp/go-multierror v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/go-version v1.2.0
 	github.com/hashicorp/hcl/v2 v2.5.2-0.20200528183353-fa7c453538de
 	github.com/hashicorp/terraform-json v0.5.0
 	github.com/mh-cbon/go-fmt-fail v0.0.0-20160815164508-67765b3fbcb5
 	github.com/mitchellh/cli v1.0.0
+	github.com/mitchellh/mapstructure v1.3.2
 	github.com/pmezard/go-difflib v1.0.0
 	github.com/sourcegraph/go-lsp v0.0.0-20200117082640-b19bb38222e2
 	github.com/zclconf/go-cty v1.2.1

go.sum

@@ -57,6 +57,8 @@ github.com/mitchellh/cli v1.0.0 h1:iGBIsUe3+HZ/AD/Vd7DErOt5sU9fa8Uj7A2s1aggv1Y=
 github.com/mitchellh/cli v1.0.0/go.mod h1:hNIlj7HEI86fIcpObd7a0FcrxTWetlwJDGcceTlRvqc=
 github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7 h1:DpOJ2HYzCv8LZP15IdmG+YdwD2luVPHITV96TkirNBM=
 github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
+github.com/mitchellh/mapstructure v1.3.2 h1:mRS76wmkOn3KkKAyXDu42V+6ebnXWIztFSYGN7GeoRg=
+github.com/mitchellh/mapstructure v1.3.2/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/posener/complete v1.1.1 h1:ccV59UEOTzVDnDUEFdT95ZzHVZ+5+158q8+SJb2QV5w=

internal/settings/settings.go

@@ -0,0 +1,59 @@
+package settings
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/hashicorp/go-multierror"
+	"github.com/mitchellh/mapstructure"
+)
+
+type Options struct {
+	// RootModulePaths describes a list of absolute paths to root modules
+	RootModulePaths []string `mapstructure:"rootModulePaths"`
+
+	// TODO: Need to check for conflict with CLI flags
+	// TerraformExecPath string
+	// TerraformExecTimeout time.Duration
+	// TerraformLogFilePath string
+}
+
+func (o *Options) Validate() error {
+	var result *multierror.Error
+
+	for _, p := range o.RootModulePaths {
+		if !filepath.IsAbs(p) {
+			result = multierror.Append(result, fmt.Errorf("%q is not an absolute path", p))
+		}
+	}
+
+	return result.ErrorOrNil()
+}
+
+type DecodedOptions struct {
+	Options    *Options
+	UnusedKeys []string
+}
+
+func DecodeOptions(input interface{}) (*DecodedOptions, error) {
+	var md mapstructure.Metadata
+	var options Options
+
+	config := &mapstructure.DecoderConfig{
+		Metadata: &md,
+		Result:   &options,
+	}
+	decoder, err := mapstructure.NewDecoder(config)
+	if err != nil {
+		panic(err)
+	}
+
+	if err := decoder.Decode(input); err != nil {
+		return nil, err
+	}
+
+	return &DecodedOptions{
+		Options:    &options,
+		UnusedKeys: md.Unused,
+	}, nil
+}

internal/settings/settings_test.go

@@ -0,0 +1,54 @@
+package settings
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestDecodeOptions_nil(t *testing.T) {
+	out, err := DecodeOptions(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	opts := out.Options
+
+	if opts.RootModulePaths != nil {
+		t.Fatalf("expected no options for nil, %#v given", opts.RootModulePaths)
+	}
+}
+
+func TestDecodeOptions_wrongType(t *testing.T) {
+	_, err := DecodeOptions(map[string]interface{}{
+		"rootModulePaths": "/random/path",
+	})
+	if err == nil {
+		t.Fatal("expected decoding of wrong type to result in error")
+	}
+}
+
+func TestDecodeOptions_success(t *testing.T) {
+	out, err := DecodeOptions(map[string]interface{}{
+		"rootModulePaths": []string{"/random/path"},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	opts := out.Options
+	expectedPaths := []string{"/random/path"}
+	if diff := cmp.Diff(expectedPaths, opts.RootModulePaths); diff != "" {
+		t.Fatalf("options mismatch: %s", diff)
+	}
+}
+
+func TestDecodedOptions_Validate(t *testing.T) {
+	opts := &Options{
+		RootModulePaths: []string{
+			"./relative/path",
+		},
+	}
+	err := opts.Validate()
+	if err == nil {
+		t.Fatal("expected relative path to fail validation")
+	}
+}

langserver/handlers/initialize.go

@@ -4,8 +4,10 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/creachadair/jrpc2"
 	lsctx "github.com/hashicorp/terraform-ls/internal/context"
 	ilsp "github.com/hashicorp/terraform-ls/internal/lsp"
+	"github.com/hashicorp/terraform-ls/internal/settings"
 	lsp "github.com/sourcegraph/go-lsp"
 )
 
@@ -54,6 +56,41 @@ func (lh *logHandler) Initialize(ctx context.Context, params lsp.InitializeParam
 		return serverCaps, err
 	}
 
+	out, err := settings.DecodeOptions(params.InitializationOptions)
+	if err != nil {
+		return serverCaps, err
+	}
+	err = out.Options.Validate()
+	if err != nil {
+		return serverCaps, err
+	}
+	if len(out.UnusedKeys) > 0 {
+		jrpc2.ServerPush(ctx, "window/showMessage", &lsp.ShowMessageParams{
+			Type:    lsp.MTWarning,
+			Message: fmt.Sprintf("Unknown configuration options: %q", out.UnusedKeys),
+		})
+	}
+	cfgOpts := out.Options
+
+	if len(cfgOpts.RootModulePaths) > 0 {
+		lh.logger.Printf("Attempting to add %d static root module paths", len(cfgOpts.RootModulePaths))
+		for _, rmPath := range cfgOpts.RootModulePaths {
+			rm, err := rmm.AddRootModule(rmPath)
+			if err != nil {
+				return serverCaps, err
+			}
+
+			paths := rm.PathsToWatch()
+			lh.logger.Printf("Adding %d paths of root module for watching (%s)", len(paths), rmPath)
+			err = w.AddPaths(paths)
+			if err != nil {
+				return serverCaps, err
+			}
+		}
+
+		return serverCaps, nil
+	}
+
 	walker, err := lsctx.RootModuleWalker(ctx)
 	if err != nil {
 		return serverCaps, err