Repository: uber-go/fx (Go)

Issue:
Terminate my application with exit code
Bug report from #1073 

### Discussed in https://github.com/uber-go/fx/discussions/1073

<div type='discussions-op-text'>

<sup>Originally posted by **nemliyartym** April 28, 2023</sup>
Hi all. I would like to know how can I terminate my application with the exit codes I need. I have a simple `smb `module with a run function that calls `shutdowner.Shutdown(fx.ExitCode(20))` with the code I need.

If in main I just call `app.Run()` then my app exits with code 0. Do I test it with `echo$?`. I changed `Run` to call `Start+Done+Stop` to try and get the exit code from `Done`, but that didn't work for me. I also tried to change `Done`to `Wait`, but in this case, the application hangs on the channel of wait.

Please, tell me what am I doing wrong?)

main.go
```go
func main() {
	app := fx.New(
		//fx.NopLogger,
		//config.Module,
		//logger.Module,

		smb.Module,
	)
	//app.Run()

	if err := app.Start(context.TODO()); err != nil {
		fmt.Println(err)
	}

	done := app.Done()
	fmt.Println(done)

	// wait := app.Wait()
	// sig := <-wait
	// fmt.Println(sig.ExitCode)

	if err := app.Stop(context.TODO()); err != nil {
		fmt.Println(err)
	}
}
```
smb.go
```go
type Smb interface {
}

type smb struct {
	logger *zap.Logger
}

func NewSmb(logger *zap.Logger) Smb {
	return &smb{logger: logger}
}

func Run(logger *zap.Logger, shutdowner fx.Shutdowner) error {
	logger.Info("shutdowner")
       //SET EXIT CODE
	shutdowner.Shutdown(fx.ExitCode(20))
	logger.Info("shutdowner2")
	return nil
}

var Module = fx.Module("smb",
	fx.Provide(NewSmb),
	fx.Invoke(Run),
	fx.Decorate(
		func(log *zap.Logger) *zap.Logger {
			return log.Named("smb")
		},
	),
)
```
</div>


Discussion:

Patch:
diff --git a/Makefile b/Makefile
index 54953fe94..f03be60ed 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ GO_FILES = $(shell \
 	find . '(' -path '*/.*' -o -path './vendor' -o -path '*/testdata/*' ')' -prune \
 	-o -name '*.go' -print | cut -b3-)
 
-MODULES = . ./tools ./docs
+MODULES = . ./tools ./docs ./internal/e2e
 
 # 'make cover' should not run on docs by default.
 # We run that separately explicitly on a specific platform.
diff --git a/app.go b/app.go
index d2b8caf17..bc3ed09d7 100644
--- a/app.go
+++ b/app.go
@@ -574,12 +574,12 @@ func (app *App) Run() {
 	// Historically, we do not os.Exit(0) even though most applications
 	// cede control to Fx with they call app.Run. To avoid a breaking
 	// change, never os.Exit for success.
-	if code := app.run(app.Done()); code != 0 {
+	if code := app.run(app.Wait()); code != 0 {
 		app.exit(code)
 	}
 }
 
-func (app *App) run(done <-chan os.Signal) (exitCode int) {
+func (app *App) run(done <-chan ShutdownSignal) (exitCode int) {
 	startCtx, cancel := app.clock.WithTimeout(context.Background(), app.StartTimeout())
 	defer cancel()
 
@@ -588,7 +588,8 @@ func (app *App) run(done <-chan os.Signal) (exitCode int) {
 	}
 
 	sig := <-done
-	app.log().LogEvent(&fxevent.Stopping{Signal: sig})
+	app.log().LogEvent(&fxevent.Stopping{Signal: sig.Signal})
+	exitCode = sig.ExitCode
 
 	stopCtx, cancel := app.clock.WithTimeout(context.Background(), app.StopTimeout())
 	defer cancel()
@@ -597,7 +598,7 @@ func (app *App) run(done <-chan os.Signal) (exitCode int) {
 		return 1
 	}
 
-	return 0
+	return exitCode
 }
 
 // Err returns any error encountered during New's initialization. See the


Test patch:
diff --git a/app_internal_test.go b/app_internal_test.go
index 6e54f8638..a377dd711 100644
--- a/app_internal_test.go
+++ b/app_internal_test.go
@@ -23,7 +23,6 @@ package fx
 import (
 	"errors"
 	"fmt"
-	"os"
 	"sync"
 	"testing"
 
@@ -42,7 +41,7 @@ func TestAppRun(t *testing.T) {
 	app := New(
 		WithLogger(func() fxevent.Logger { return spy }),
 	)
-	done := make(chan os.Signal)
+	done := make(chan ShutdownSignal)
 
 	var wg sync.WaitGroup
 	wg.Add(1)
@@ -51,7 +50,7 @@ func TestAppRun(t *testing.T) {
 		app.run(done)
 	}()
 
-	done <- _sigINT
+	done <- ShutdownSignal{Signal: _sigINT}
 	wg.Wait()
 
 	assert.Equal(t, []string{
diff --git a/internal/e2e/README.md b/internal/e2e/README.md
new file mode 100644
index 000000000..0c39606d0
--- /dev/null
+++ b/internal/e2e/README.md
@@ -0,0 +1,6 @@
+This directory holds end-to-end tests for Fx.
+Each subdirectory holds a complete Fx application
+and a test for it.
+
+This is marked as a separate Go module to prevent this code from being bundled
+with the Fx library and allow for dependencies that don't leak into Fx.
diff --git a/internal/e2e/go.mod b/internal/e2e/go.mod
new file mode 100644
index 000000000..c771bc0b7
--- /dev/null
+++ b/internal/e2e/go.mod
@@ -0,0 +1,21 @@
+module go.uber.org/fx/internal/e2e
+
+go 1.20
+
+require (
+	github.com/stretchr/testify v1.8.2
+	go.uber.org/fx v1.19.2
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	go.uber.org/atomic v1.7.0 // indirect
+	go.uber.org/dig v1.16.1 // indirect
+	go.uber.org/multierr v1.6.0 // indirect
+	go.uber.org/zap v1.23.0 // indirect
+	golang.org/x/sys v0.0.0-20220412211240-33da011f77ad // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
+
+replace go.uber.org/fx => ../..
diff --git a/internal/e2e/go.sum b/internal/e2e/go.sum
new file mode 100644
index 000000000..55ec2f69e
--- /dev/null
+++ b/internal/e2e/go.sum
@@ -0,0 +1,31 @@
+github.com/benbjohnson/clock v1.3.0 h1:ip6w0uFQkncKQ979AypyG0ER7mqUSBdKLOgAle/AT8A=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+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/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
+go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
+go.uber.org/dig v1.16.1 h1:+alNIBsl0qfY0j6epRubp/9obgtrObRAc5aD+6jbWY8=
+go.uber.org/dig v1.16.1/go.mod h1:557JTAUZT5bUK0SvCwikmLPPtdQhfvLYtO5tJgQSbnk=
+go.uber.org/goleak v1.1.11 h1:wy28qYRKZgnJTxGxvye5/wgWr1EKjmUDGYox5mGlRlI=
+go.uber.org/multierr v1.6.0 h1:y6IPFStTAIT5Ytl7/XYmHvzXQ7S3g/IeZW9hyZ5thw4=
+go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=
+go.uber.org/zap v1.23.0 h1:OjGQ5KQDEUawVHxNwQgPpiypGHOxo2mNZsOqTak4fFY=
+go.uber.org/zap v1.23.0/go.mod h1:D+nX8jyLsMHMYrln8A0rJjFt/T/9/bGgIhAqxv5URuY=
+golang.org/x/sys v0.0.0-20220412211240-33da011f77ad h1:ntjMns5wyP/fN65tdBD4g8J5w8n015+iIIs9rtjXkY0=
+golang.org/x/sys v0.0.0-20220412211240-33da011f77ad/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/e2e/shutdowner_run_exitcode/main.go b/internal/e2e/shutdowner_run_exitcode/main.go
new file mode 100644
index 000000000..58872c6ce
--- /dev/null
+++ b/internal/e2e/shutdowner_run_exitcode/main.go
@@ -0,0 +1,34 @@
+// Copyright (c) 2023 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package main
+
+import (
+	"go.uber.org/fx"
+)
+
+func main() {
+	fx.New(
+		fx.Invoke(func(shutdowner fx.Shutdowner) error {
+			shutdowner.Shutdown(fx.ExitCode(20))
+			return nil
+		}),
+	).Run()
+}
diff --git a/internal/e2e/shutdowner_run_exitcode/main_test.go b/internal/e2e/shutdowner_run_exitcode/main_test.go
new file mode 100644
index 000000000..849be9fe7
--- /dev/null
+++ b/internal/e2e/shutdowner_run_exitcode/main_test.go
@@ -0,0 +1,72 @@
+// Copyright (c) 2023 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package main
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/fx/internal/testutil"
+)
+
+// Hijacks the test binary so that the test can run main() as a subprocess
+// instead of trying to compile the program and run it directly.
+func TestMain(m *testing.M) {
+	// If the test binary is named "app", then we're running as a subprocess.
+	// Otherwise, run the tests.
+	switch filepath.Base(os.Args[0]) {
+	case "app":
+		main()
+		os.Exit(0)
+	default:
+		os.Exit(m.Run())
+	}
+}
+
+// Verifies that an Fx program running with Run
+// exits with the exit code passed to Shutdowner.
+//
+// Regression test for https://github.com/uber-go/fx/issues/1074.
+func TestShutdownExitCode(t *testing.T) {
+	exe, err := os.Executable()
+	require.NoError(t, err)
+
+	out := testutil.WriteSyncer{T: t}
+
+	// Run the test binary with the name 'app' so that it runs main().
+	cmd := exec.Command(exe)
+	cmd.Args[0] = "app"
+	cmd.Stdout = &out
+	cmd.Stderr = &out
+
+	// The program should exit with code 20.
+	err = cmd.Run()
+	require.Error(t, err)
+
+	var exitErr *exec.ExitError
+	require.ErrorAs(t, err, &exitErr)
+
+	assert.Equal(t, 20, exitErr.ExitCode())
+}