fix(desktop): open default browser on startup (#2095)

Fixes #934

## Summary

The Go desktop binary started its local server and printed the URL,
but never opened a browser automatically.

This PR:

- opens the default browser after the listener successfully binds
- uses the actual runtime URL
- uses a stdlib-only cross-platform launcher
- keeps browser-open failures non-fatal
- adds `--no-browser` for headless/Docker use
- leaves the normal Vite/web development flow unchanged

The listener is created before launching the browser so the browser
cannot race the server startup path.

## Platform behavior

- Windows: `rundll32 url.dll,FileProtocolHandler`
- macOS: `open`
- Linux: `xdg-open`

No shell command strings are used; arguments are passed directly through
`exec.Command`.

## Testing

- `go test ./...`
- `go vet ./...`
- `go build ./...`
- `git diff --check`
- repeated manual Windows startup verification (3 clean runs, confirmed
the
  browser opened and hit the server, no duplicate launches)
- `--no-browser` verification (confirmed no launch attempt occurs)
- non-fatal launcher failure covered by a unit test that injects a
  nonexistent opener binary

macOS/Linux launch paths were not runtime-tested on this Windows machine
—
they follow the standard `open`/`xdg-open` convention used across other
Go
CLIs but are unverified here. The full packaged release flow (`gox`,
`go.rice`, `go-winres`) was not exercised locally.

CHANGELOG.md

@@ -9,6 +9,7 @@
 
 ### 🐞 Bug fixes
 - The map's data listener now fires on tile loads again, so source and vector layer field autocompletion is populated
+- The `maputnik` desktop binary now opens the default browser automatically on startup (opt out with `--no-browser`)
 - _...Add new stuff here..._
 
 ## 3.1.0

desktop/go.mod

@@ -9,19 +9,14 @@ require (
 	github.com/gorilla/mux v1.8.0
 	github.com/gorilla/websocket v1.5.0
 	github.com/maputnik/desktop v1.0.7
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c
 	github.com/urfave/cli v1.22.12
 )
 
 require (
-	github.com/GeertJohan/go.incremental v1.0.0 // indirect
-	github.com/akavel/rsrc v0.8.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
 	github.com/daaku/go.zipexe v1.0.2 // indirect
 	github.com/felixge/httpsnoop v1.0.1 // indirect
-	github.com/jessevdk/go-flags v1.4.0 // indirect
-	github.com/nkovacs/streamquote v1.0.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
-	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/valyala/fasttemplate v1.0.1 // indirect
-	golang.org/x/sys v0.0.0-20220908164124-27713097b956 // indirect
+	golang.org/x/sys v0.1.0 // indirect
 )

desktop/go.sum

@@ -1,9 +1,7 @@
 github.com/BurntSushi/toml v1.2.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
-github.com/GeertJohan/go.incremental v1.0.0 h1:7AH+pY1XUgQE4Y1HcXYaMqAI0m9yrFqo/jt0CW30vsg=
 github.com/GeertJohan/go.incremental v1.0.0/go.mod h1:6fAjUhbVuX1KcMD3c8TEgVUqmo4seqhv0i0kdATSkM0=
 github.com/GeertJohan/go.rice v1.0.3 h1:k5viR+xGtIhF61125vCE1cmJ5957RQGXG6dmbaWZSmI=
 github.com/GeertJohan/go.rice v1.0.3/go.mod h1:XVdrU4pW00M4ikZed5q56tPf1v2KwnIKeIdc9CBYNt4=
-github.com/akavel/rsrc v0.8.0 h1:zjWn7ukO9Kc5Q62DOJCcxGpXC18RawVtYAGdz2aLlfw=
 github.com/akavel/rsrc v0.8.0/go.mod h1:uLoCtb9J+EyAqh+26kdrTgmzRBFPGOolLWKpdxkKq+c=
 github.com/cpuguy83/go-md2man/v2 v2.0.2 h1:p1EgwI/C7NhT0JmVkwCD2ZBK8j4aeHQX2pMHHBfMQ6w=
 github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
@@ -22,12 +20,12 @@ github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
 github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
 github.com/gorilla/websocket v1.5.0 h1:PPwGk2jz7EePpoHN/+ClbZu8SPxiqlu12wZP/3sWmnc=
 github.com/gorilla/websocket v1.5.0/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
-github.com/jessevdk/go-flags v1.4.0 h1:4IU2WS7AumrZ/40jfhf4QVDMsQwqA7VEHozFRrGARJA=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
 github.com/maputnik/desktop v1.0.7 h1:rdFg7emIJOT3YsZpwqSChmWtMOvu+T4h6WwVQAZP9n4=
 github.com/maputnik/desktop v1.0.7/go.mod h1:wmDjHUztx9jOBz0I22589yWguAGdV/sEM57YANpN8oQ=
-github.com/nkovacs/streamquote v1.0.0 h1:PmVIV08Zlx2lZK5fFZlMZ04eHcDTIFJCv/5/0twVUow=
 github.com/nkovacs/streamquote v1.0.0/go.mod h1:BN+NaZ2CmdKqUuTUXUEm9j95B2TRbpOWpxbJYzzgUsc=
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmdv1U2eRNDiU2ErMBj1gwrq8eQ=
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 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/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
@@ -41,12 +39,11 @@ github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKs
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/urfave/cli v1.22.12 h1:igJgVw1JdKH+trcLWLeLwZjU9fEfPesQ+9/e4MQ44S8=
 github.com/urfave/cli v1.22.12/go.mod h1:sSBEIC79qR6OvcmsD4U3KABeOTxDqQtdDnaFuUN30b8=
-github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
-github.com/valyala/fasttemplate v1.0.1 h1:tY9CJiPnMXf1ERmG2EyK7gNUd+c6RKGD0IfU8WdUSz8=
 github.com/valyala/fasttemplate v1.0.1/go.mod h1:UQGH1tvbgY+Nz5t2n7tXsz52dQxojPUpymEIMZ47gx8=
-golang.org/x/sys v0.0.0-20220908164124-27713097b956 h1:XeJjHH1KiLpKGb6lvMiksZ9l0fVUh+AmGcm0nOMEBOY=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

desktop/maputnik.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"net"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -9,6 +10,7 @@ import (
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
 	"github.com/maputnik/desktop/filewatch"
+	"github.com/pkg/browser"
 	"github.com/urfave/cli"
 )
 
@@ -36,6 +38,10 @@ func main() {
 			Name:  "static",
 			Usage: "Serve directory under /static/",
 		},
+		&cli.BoolFlag{
+			Name:  "no-browser",
+			Usage: "Do not automatically open the default browser",
+		},
 	}
 
 	app.Action = func(c *cli.Context) error {
@@ -71,8 +77,26 @@ func main() {
 		loggedRouter := handlers.LoggingHandler(os.Stdout, router)
 		corsRouter := handlers.CORS(handlers.AllowedHeaders([]string{"Content-Type"}), handlers.AllowedMethods([]string{"GET", "PUT"}), handlers.AllowedOrigins([]string{"*"}), handlers.AllowCredentials())(loggedRouter)
 
-		fmt.Printf("Exposing Maputnik on http://localhost:%d\n", c.Int("port"))
-		return http.ListenAndServe(fmt.Sprintf(":%d", c.Int("port")), corsRouter)
+		listener, err := net.Listen("tcp", fmt.Sprintf(":%d", c.Int("port")))
+		if err != nil {
+			return err
+		}
+
+		url := fmt.Sprintf("http://localhost:%d", c.Int("port"))
+		fmt.Printf("Exposing Maputnik on %s\n", url)
+
+		// Listener is already accepting connections, so this can't race http.Serve below.
+		// xdg-open is known to hang on some headless Linux setups, so this runs in its own
+		// goroutine to keep a stuck opener from stalling server startup.
+		if !c.Bool("no-browser") {
+			go func() {
+				if err := browser.OpenURL(url); err != nil {
+					fmt.Printf("Could not open browser automatically: %s\nPlease open %s manually.\n", err, url)
+				}
+			}()
+		}
+
+		return http.Serve(listener, corsRouter)
 	}
 
 	app.Run(os.Args)