don't swallow configuration error messages (#204)

* wrap config error and catch any unhandled errors

* add a test

* grammar

cmd/server/main.go

@@ -42,7 +42,12 @@ import (
 // main entry point for the web server
 func main() {
 	app := buildCLI()
-	_ = app.Run(os.Args)
+	err := app.Run(os.Args)
+	if err != nil {
+		// An unhandled error was returned, wrap it and run it through the default exit code handler. Any errors
+		// that make it here should be caught further up the call stack and wrapped with cli.Exit and the proper exit code.
+		cli.HandleExitCoder(cli.Exit(fmt.Sprintf("Unexpected error encountered: %v.", err), 9))
+	}
 }
 
 // buildCLI is the main entry point for the web server
@@ -88,7 +93,7 @@ func buildCLI() *cli.App {
 
 				cfg, err := cfgProvider.GetConfig()
 				if err != nil {
-					return err
+					return cli.Exit(err, 1)
 				}
 
 				opts := []server_options.ServerOption{

cmd/server/main_test.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"bytes"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/urfave/cli/v2"
+)
+
+func TestExitCodesWorkProperly(t *testing.T) {
+	testcases := []struct {
+		arguments        []string
+		expectedExitCode int
+		expectedText     string
+	}{
+		{arguments: []string{}, expectedExitCode: 0, expectedText: "USAGE"},
+		{arguments: []string{"--config", "/tmp/doesnotexist123", "start"}, expectedExitCode: 1, expectedText: "no config files found"},
+	}
+
+	cli.OsExiter = func(int) {}
+	for idx, tc := range testcases {
+		t.Run(strconv.Itoa(idx), func(t *testing.T) {
+			tc := tc
+
+			c := buildCLI()
+			c.ExitErrHandler = func(_ *cli.Context, err error) {}
+
+			var buf bytes.Buffer
+			c.Writer = &buf
+			c.ErrWriter = &buf
+
+			args := append([]string{"./ui-server"}, tc.arguments...)
+			err := c.Run(args)
+
+			if tc.expectedExitCode != 0 {
+				assert.Error(t, err)
+			}
+
+			if err != nil {
+				ec := err.(cli.ExitCoder)
+				assert.Equal(t, tc.expectedExitCode, ec.ExitCode())
+				assert.Contains(t, ec.Error(), tc.expectedText)
+			} else {
+				assert.Contains(t, buf.String(), tc.expectedText)
+			}
+		})
+	}
+}