Merge pull request #3 from gruntwork-io/error-messages

Terraform error handling

engine/engine.go

@@ -19,8 +19,9 @@ import (
 )
 
 const (
-	wgSize     = 2
-	iacCommand = "terraform"
+	wgSize          = 2
+	iacCommand      = "terraform"
+	errorResultCode = 1
 )
 
 type TerraformEngine struct {
@@ -49,10 +50,12 @@ func (c *TerraformEngine) Run(req *tgengine.RunRequest, stream tgengine.Engine_R
 
 	stdoutPipe, err := cmd.StdoutPipe()
 	if err != nil {
+		sendError(stream, err)
 		return err
 	}
 	stderrPipe, err := cmd.StderrPipe()
 	if err != nil {
+		sendError(stream, err)
 		return err
 	}
 
@@ -78,6 +81,7 @@ func (c *TerraformEngine) Run(req *tgengine.RunRequest, stream tgengine.Engine_R
 	}
 
 	if err := cmd.Start(); err != nil {
+		sendError(stream, err)
 		return err
 	}
 
@@ -99,10 +103,7 @@ func (c *TerraformEngine) Run(req *tgengine.RunRequest, stream tgengine.Engine_R
 				}
 				break
 			}
-			err = stream.Send(&tgengine.RunResponse{
-				Stdout: string(char),
-			})
-			if err != nil {
+			if err = stream.Send(&tgengine.RunResponse{Stdout: string(char)}); err != nil {
 				log.Errorf("Error sending stdout: %v", err)
 				return
 			}
@@ -122,10 +123,7 @@ func (c *TerraformEngine) Run(req *tgengine.RunRequest, stream tgengine.Engine_R
 				}
 				break
 			}
-			err = stream.Send(&tgengine.RunResponse{
-				Stderr: string(char),
-			})
-			if err != nil {
+			if err = stream.Send(&tgengine.RunResponse{Stderr: string(char)}); err != nil {
 				log.Errorf("Error sending stderr: %v", err)
 				return
 			}
@@ -141,16 +139,18 @@ func (c *TerraformEngine) Run(req *tgengine.RunRequest, stream tgengine.Engine_R
 			resultCode = 1
 		}
 	}
-
-	err = stream.Send(&tgengine.RunResponse{
-		ResultCode: int32(resultCode),
-	})
-	if err != nil {
+	if err := stream.Send(&tgengine.RunResponse{ResultCode: int32(resultCode)}); err != nil {
 		return err
 	}
 	return nil
 }
 
+func sendError(stream tgengine.Engine_RunServer, err error) {
+	if err = stream.Send(&tgengine.RunResponse{Stderr: fmt.Sprintf("%v", err), ResultCode: errorResultCode}); err != nil {
+		log.Warnf("Error sending response: %v", err)
+	}
+}
+
 func (c *TerraformEngine) Shutdown(req *tgengine.ShutdownRequest, stream tgengine.Engine_ShutdownServer) error {
 	log.Info("Shutdown Terraform engine")
 

engine/engine_test.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"os"
 	"os/exec"
 
@@ -120,12 +122,13 @@ func TestTerraformEngine_Init(t *testing.T) {
 	mockStream := &MockInitServer{}
 
 	err := engine.Init(&tgengine.InitRequest{}, mockStream)
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	assert.Equal(t, 1, len(mockStream.Responses))
 	assert.Equal(t, "Terraform Initialization completed\n", mockStream.Responses[0].Stdout)
 }
 
 func TestTerraformEngine_Run(t *testing.T) {
+	t.Parallel()
 	engine := &TerraformEngine{}
 	mockStream := &MockRunServer{}
 
@@ -137,7 +140,7 @@ func TestTerraformEngine_Run(t *testing.T) {
 		EnvVars: map[string]string{"FOO": "bar"},
 	}
 	err := engine.Run(req, mockStream)
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	assert.True(t, len(mockStream.Responses) > 0)
 	// merge stdout from all responses to a string
 	var output string
@@ -149,12 +152,41 @@ func TestTerraformEngine_Run(t *testing.T) {
 	assert.Contains(t, output, "Usage: terraform [global options] <subcommand> [args]")
 }
 
+func TestTerraformEngineError(t *testing.T) {
+	t.Parallel()
+	engine := &TerraformEngine{}
+	mockStream := &MockRunServer{}
+
+	cmd := "terraform"
+	args := []string{"not-a-valid-command"}
+	req := &tgengine.RunRequest{
+		Command: cmd,
+		Args:    args,
+	}
+	err := engine.Run(req, mockStream)
+	require.NoError(t, err)
+	assert.True(t, len(mockStream.Responses) > 0)
+	// merge stdout from all responses to a string
+	var output string
+
+	for _, response := range mockStream.Responses {
+		if response.Stderr != "" {
+			output += response.Stderr
+		}
+	}
+	// get status code from last response
+	code := mockStream.Responses[len(mockStream.Responses)-1].ResultCode
+	assert.Contains(t, output, "Terraform has no command named \"not-a-valid-command\"")
+	assert.NotEqual(t, 0, code)
+}
+
 func TestTerraformEngine_Shutdown(t *testing.T) {
+	t.Parallel()
 	engine := &TerraformEngine{}
 	mockStream := &MockShutdownServer{}
 
 	err := engine.Shutdown(&tgengine.ShutdownRequest{}, mockStream)
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	assert.Equal(t, 1, len(mockStream.Responses))
 	assert.Equal(t, "Terraform Shutdown completed\n", mockStream.Responses[0].Stdout)
 }