Support passing a path for the TF binary

Fixes #80

commands/serve_command.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"path/filepath"
 	"strings"
 	"syscall"
 
@@ -22,6 +23,7 @@ type ServeCommand struct {
 	// flags
 	port          int
 	logFilePath   string
+	tfExecPath    string
 	tfExecLogPath string
 }
 
@@ -31,6 +33,7 @@ func (c *ServeCommand) flags() *flag.FlagSet {
 	fs.IntVar(&c.port, "port", 0, "port number to listen on (turns server into TCP mode)")
 	fs.StringVar(&c.logFilePath, "log-file", "", "path to a file to log into with support "+
 		"for variables (e.g. Timestamp, Pid, Ppid) via Go template syntax {{.VarName}}")
+	fs.StringVar(&c.tfExecPath, "tf-exec", "", "path to Terraform binary")
 	fs.StringVar(&c.tfExecLogPath, "tf-log-file", "", "path to a file for Terraform executions"+
 		" to be logged into with support for variables (e.g. Timestamp, Pid, Ppid) via Go template"+
 		" syntax {{.VarName}}")
@@ -79,6 +82,31 @@ func (c *ServeCommand) Run(args []string) int {
 	srv := langserver.NewLangServer(ctx, handlers.NewSession)
 	srv.SetLogger(logger)
 
+	if c.tfExecPath != "" {
+		path := c.tfExecPath
+
+		logger.Printf("Setting Terraform exec path to %q", path)
+
+		// just some sanity checking here, no need to get too specific otherwise will be complex cross-OS
+		if !filepath.IsAbs(path) {
+			c.Ui.Error(fmt.Sprintf("Expected absolute path for Terraform binary, got %q", path))
+			return 1
+		}
+		stat, err := os.Stat(path)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Unable to find Terraform binary: %s", err))
+			return 1
+		}
+		if stat.IsDir() {
+			c.Ui.Error(fmt.Sprintf("Expected a Terraform binary, got a directory: %q", path))
+			return 1
+		}
+
+		srv.SetDiscoveryFunc(func() (string, error) {
+			return path, nil
+		})
+	}
+
 	if c.port != 0 {
 		err := srv.StartTCP(fmt.Sprintf("localhost:%d", c.port))
 		if err != nil {

langserver/handlers/service.go

@@ -28,7 +28,7 @@ type service struct {
 	sessCtx     context.Context
 	stopSession context.CancelFunc
 
-	tfPath       discovery.DiscoveryFunc
+	tfDiscoFunc  discovery.DiscoveryFunc
 	ss           *schema.Storage
 	executorFunc func(ctx context.Context, execPath string) *exec.Executor
 }
@@ -44,7 +44,7 @@ func NewSession(srvCtx context.Context) session.Session {
 		sessCtx:      sessCtx,
 		stopSession:  stopSession,
 		executorFunc: exec.NewExecutor,
-		tfPath:       d.LookPath,
+		tfDiscoFunc:  d.LookPath,
 		ss:           schema.NewStorage(),
 	}
 }
@@ -53,6 +53,10 @@ func (svc *service) SetLogger(logger *log.Logger) {
 	svc.logger = logger
 }
 
+func (svc *service) SetDiscoveryFunc(f discovery.DiscoveryFunc) {
+	svc.tfDiscoFunc = f
+}
+
 // Assigner builds out the jrpc2.Map according to the LSP protocol
 // and passes related dependencies to handlers via context
 func (svc *service) Assigner() (jrpc2.Assigner, error) {
@@ -81,7 +85,7 @@ func (svc *service) Assigner() (jrpc2.Assigner, error) {
 			ctx = lsctx.WithFilesystem(fs, ctx)
 			ctx = lsctx.WithClientCapabilitiesSetter(cc, ctx)
 
-			tfPath, err := svc.tfPath()
+			tfPath, err := svc.tfDiscoFunc()
 			if err != nil {
 				return nil, err
 			}
@@ -157,7 +161,7 @@ func (svc *service) Assigner() (jrpc2.Assigner, error) {
 
 			ctx = lsctx.WithFilesystem(fs, ctx)
 
-			tfPath, err := svc.tfPath()
+			tfPath, err := svc.tfDiscoFunc()
 			if err != nil {
 				return nil, err
 			}

langserver/handlers/service_mock.go

@@ -29,8 +29,8 @@ func (ms *mockSession) new(srvCtx context.Context) session.Session {
 		executorFunc: func(context.Context, string) *exec.Executor {
 			return exec.MockExecutor(ms.mid)
 		},
-		tfPath: d.LookPath,
-		ss:     schema.MockStorage(nil),
+		tfDiscoFunc: d.LookPath,
+		ss:          schema.MockStorage(nil),
 	}
 
 	return svc

langserver/langserver.go

@@ -12,14 +12,17 @@ import (
 	"github.com/creachadair/jrpc2"
 	"github.com/creachadair/jrpc2/channel"
 	"github.com/creachadair/jrpc2/server"
+
+	"github.com/hashicorp/terraform-ls/internal/terraform/discovery"
 	"github.com/hashicorp/terraform-ls/langserver/session"
 )
 
 type langServer struct {
-	srvCtx     context.Context
-	logger     *log.Logger
-	srvOptions *jrpc2.ServerOptions
-	newSession session.SessionFactory
+	srvCtx      context.Context
+	logger      *log.Logger
+	tfDiscoFunc discovery.DiscoveryFunc
+	srvOptions  *jrpc2.ServerOptions
+	newSession  session.SessionFactory
 }
 
 func NewLangServer(srvCtx context.Context, sf session.SessionFactory) *langServer {
@@ -41,9 +44,16 @@ func (ls *langServer) SetLogger(logger *log.Logger) {
 	ls.logger = logger
 }
 
+func (ls *langServer) SetDiscoveryFunc(f discovery.DiscoveryFunc) {
+	ls.tfDiscoFunc = f
+}
+
 func (ls *langServer) newService() server.Service {
 	svc := ls.newSession(ls.srvCtx)
 	svc.SetLogger(ls.logger)
+	if ls.tfDiscoFunc != nil {
+		svc.SetDiscoveryFunc(ls.tfDiscoFunc)
+	}
 	return svc
 }
 

langserver/session/types.go

@@ -5,12 +5,15 @@ import (
 	"log"
 
 	"github.com/creachadair/jrpc2"
+
+	"github.com/hashicorp/terraform-ls/internal/terraform/discovery"
 )
 
 type Session interface {
 	Assigner() (jrpc2.Assigner, error)
 	Finish(jrpc2.ServerStatus)
 	SetLogger(*log.Logger)
+	SetDiscoveryFunc(discovery.DiscoveryFunc)
 }
 
 type SessionFactory func(context.Context) Session