Launch V2: automatically generate valid app name (#2806)

* `launch` v2: check app name is available, attempt to add unique suffix

removed herobrine

Author: Allison Pierson

internal/command/launch/plan_builder.go

@@ -15,9 +15,12 @@ import (
 	"github.com/superfly/flyctl/internal/cmdutil"
 	"github.com/superfly/flyctl/internal/command/launch/plan"
 	"github.com/superfly/flyctl/internal/flag"
+	"github.com/superfly/flyctl/internal/flyerr"
+	"github.com/superfly/flyctl/internal/haikunator"
 	"github.com/superfly/flyctl/internal/prompt"
 	"github.com/superfly/flyctl/iostreams"
 	"github.com/superfly/flyctl/scanner"
+	"github.com/superfly/graphql"
 )
 
 // Cache values between buildManifest and stateFromManifest
@@ -31,6 +34,14 @@ type planBuildCache struct {
 	srcInfo   *scanner.SourceInfo
 }
 
+func appNameTakenErr(appName string) error {
+	return flyerr.GenericErr{
+		Err:      fmt.Sprintf("app name %s is already taken", appName),
+		Descript: "each Fly.io app must have a unique name",
+		Suggest:  "Please specify a different app name with --name",
+	}
+}
+
 func buildManifest(ctx context.Context) (*LaunchManifest, *planBuildCache, error) {
 
 	appConfig, copiedConfig, err := determineBaseAppConfig(ctx)
@@ -183,6 +194,10 @@ func stateFromManifest(ctx context.Context, m LaunchManifest, optionalCache *pla
 		}
 	}
 
+	if taken, _ := appNameTaken(ctx, appConfig.AppName); taken {
+		return nil, appNameTakenErr(appConfig.AppName)
+	}
+
 	workingDir := flag.GetString(ctx, "path")
 	if absDir, err := filepath.Abs(workingDir); err == nil {
 		workingDir = absDir
@@ -274,9 +289,39 @@ func determineAppName(ctx context.Context, configPath string) (string, string, e
 	if appName == "" {
 		return "", "", errors.New("enable to determine app name, please specify one with --name")
 	}
+	// If the app name is already taken, try to generate a unique suffix.
+	if taken, _ := appNameTaken(ctx, appName); taken {
+		delimiter := "-"
+		var newName string
+		found := false
+		for i := 1; i < 10; i++ {
+			newName = fmt.Sprintf("%s%s%s", appName, delimiter, haikunator.Haikunator().Delimiter(delimiter))
+			if taken, _ := appNameTaken(ctx, newName); !taken {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return "", "", appNameTakenErr(appName)
+		}
+		appName = newName
+	}
 	return appName, "derived from your directory name", nil
 }
 
+func appNameTaken(ctx context.Context, name string) (bool, error) {
+	client := client.FromContext(ctx).API()
+	_, err := client.GetAppBasic(ctx, name)
+	if err != nil {
+		if api.IsNotFoundError(err) || graphql.IsNotFoundError(err) {
+			return false, nil
+		}
+		return false, err
+	}
+
+	return true, nil
+}
+
 // determineOrg returns the org specified on the command line, or the personal org if left unspecified
 func determineOrg(ctx context.Context) (*api.Organization, string, error) {
 	var (

internal/haikunator/haikunator.go

@@ -0,0 +1,89 @@
+package haikunator
+
+import (
+	"crypto/rand"
+	"math/big"
+	rand2 "math/rand"
+	"strconv"
+	"strings"
+
+	"github.com/superfly/flyctl/helpers"
+)
+
+var adjectives = strings.Fields(`
+	autumn hidden bitter misty silent empty dry dark summer
+	icy delicate quiet white cool spring winter patient
+	twilight dawn crimson wispy weathered blue billowing
+	broken cold damp falling frosty green long late lingering
+	bold little morning muddy old red rough still small
+	sparkling thrumming shy wandering withered wild black
+	young holy solitary fragrant aged snowy proud floral
+	restless divine polished ancient purple lively nameless
+`)
+var nouns = strings.Fields(`
+	waterfall river breeze moon rain wind sea morning
+	snow lake sunset pine shadow leaf dawn glitter forest
+	hill cloud meadow sun glade bird brook butterfly
+	bush dew dust field fire flower firefly feather grass
+	haze mountain night pond darkness snowflake silence
+	sound sky shape surf thunder violet water wildflower
+	wave water resonance sun log dream cherry tree fog
+	frost voice paper frog smoke star
+`)
+
+type builder struct {
+	tokRange  int
+	delimiter string
+}
+
+type Builder interface {
+	TokenRange(r int) Builder
+	Delimiter(d string) Builder
+	Build() string
+	String() string
+}
+
+func randN(max int) int {
+	ret, err := rand.Int(rand.Reader, big.NewInt(int64(max)))
+	if err != nil {
+		// Fallback to "insecure" random
+		// it doesn't really matter, this is not security critical
+		return rand2.Intn(max) // skipcq: GSC-G404
+	}
+	return int(ret.Int64())
+}
+
+func choose(list []string) string {
+	return list[randN(len(list))]
+}
+
+func Haikunator() Builder {
+	return &builder{
+		tokRange:  9999,
+		delimiter: "-",
+	}
+}
+
+func (b *builder) TokenRange(r int) Builder {
+	newB := helpers.Clone(b)
+	newB.tokRange = r
+	return newB
+}
+func (b *builder) Delimiter(d string) Builder {
+	newB := helpers.Clone(b)
+	newB.delimiter = d
+	return newB
+}
+func (b *builder) Build() string {
+	sections := []string{
+		choose(adjectives),
+		choose(nouns),
+	}
+	if b.tokRange > 0 {
+		sections = append(sections, strconv.Itoa(randN(b.tokRange)))
+	}
+	return strings.Join(sections, b.delimiter)
+}
+func (b *builder) String() string {
+	return b.Build()
+}