feat(login): use BROWSER environment variable to open browser window

closes hashicorp#34902

commands.go

@@ -85,6 +85,13 @@ func initCommands(
 
 	wd := WorkingDir(originalWorkingDir, os.Getenv("TF_DATA_DIR"))
 
+	var browserLauncher webbrowser.Launcher
+	if _, ok := os.LookupEnv("TF_BROWSER_ENV"); ok {
+		browserLauncher = webbrowser.NewBrowserEnvLauncher()
+	} else {
+		browserLauncher = webbrowser.NewNativeLauncher()
+	}
+
 	meta := command.Meta{
 		WorkingDir: wd,
 		Streams:    streams,
@@ -95,7 +102,7 @@ func initCommands(
 		Ui:               Ui,
 
 		Services:        services,
-		BrowserLauncher: webbrowser.NewNativeLauncher(),
+		BrowserLauncher: browserLauncher,
 
 		RunningInAutomation: inAutomation,
 		CLIConfigDir:        configDir,

internal/command/webbrowser/browserenv.go

@@ -0,0 +1,37 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package webbrowser
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"time"
+
+	"github.com/pkg/browser"
+)
+
+// NewBrowserEnvLauncher creates and returns a Launcher that will attempt to use 
+// BROWSER environment , otherwise full back to the browser-launching mechanisms of 
+// the operating system where the program is currently running.
+func NewBrowserEnvLauncher() Launcher {
+	return browserEnvLauncher{}
+}
+
+type browserEnvLauncher struct{}
+
+func (l browserEnvLauncher) OpenURL(url string) error {
+	browserEnv := os.Getenv("BROWSER")
+	if browserEnv != "" {
+		browserSh := fmt.Sprintf("%s '%s'", browserEnv, url)
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+		cmd := exec.CommandContext(ctx, "sh", "-c", browserSh)
+		_, err := cmd.CombinedOutput()
+		return err
+	}
+
+	return browser.OpenURL(url)
+}