Merge pull request #141 from meatballhat/multi-env-var

Adding support for multiple env var "cascade"

README.md

@@ -172,6 +172,8 @@ app.Flags = []cli.Flag {
 }
 ```
 
+That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error.
+
 #### Values from the Environment
 
 You can also have the default value set from the environment via `EnvVar`.  e.g.
@@ -187,7 +189,18 @@ app.Flags = []cli.Flag {
 }
 ```
 
-That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error.
+The `EnvVar` may also be given as a comma-delimited "cascade", where the first environment variable that resolves is used as the default.
+
+``` go
+app.Flags = []cli.Flag {
+  cli.StringFlag{
+    Name: "lang, l",
+    Value: "english",
+    Usage: "language for the greeting",
+    EnvVar: "LEGACY_COMPAT_LANG,APP_LANG,LANG",
+  },
+}
+```
 
 ### Subcommands
 

flag.go

@@ -74,8 +74,12 @@ func (f GenericFlag) String() string {
 func (f GenericFlag) Apply(set *flag.FlagSet) {
 	val := f.Value
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				val.Set(envVal)
+				break
+			}
 		}
 	}
 
@@ -118,12 +122,17 @@ func (f StringSliceFlag) String() string {
 
 func (f StringSliceFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				newVal := &StringSlice{}
 				for _, s := range strings.Split(envVal, ",") {
+					s = strings.TrimSpace(s)
 					newVal.Set(s)
 				}
 				f.Value = newVal
+				break
+			}
 		}
 	}
 
@@ -172,15 +181,20 @@ func (f IntSliceFlag) String() string {
 
 func (f IntSliceFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				newVal := &IntSlice{}
 				for _, s := range strings.Split(envVal, ",") {
+					s = strings.TrimSpace(s)
 					err := newVal.Set(s)
 					if err != nil {
 						fmt.Fprintf(os.Stderr, err.Error())
 					}
 				}
 				f.Value = newVal
+				break
+			}
 		}
 	}
 
@@ -206,11 +220,15 @@ func (f BoolFlag) String() string {
 func (f BoolFlag) Apply(set *flag.FlagSet) {
 	val := false
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				envValBool, err := strconv.ParseBool(envVal)
 				if err == nil {
 					val = envValBool
 				}
+				break
+			}
 		}
 	}
 
@@ -236,10 +254,14 @@ func (f BoolTFlag) String() string {
 func (f BoolTFlag) Apply(set *flag.FlagSet) {
 	val := true
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				envValBool, err := strconv.ParseBool(envVal)
 				if err == nil {
 					val = envValBool
+					break
+				}
 			}
 		}
 	}
@@ -275,8 +297,12 @@ func (f StringFlag) String() string {
 
 func (f StringFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				f.Value = envVal
+				break
+			}
 		}
 	}
 
@@ -302,10 +328,14 @@ func (f IntFlag) String() string {
 
 func (f IntFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				envValInt, err := strconv.ParseUint(envVal, 10, 64)
 				if err == nil {
 					f.Value = int(envValInt)
+					break
+				}
 			}
 		}
 	}
@@ -332,10 +362,14 @@ func (f DurationFlag) String() string {
 
 func (f DurationFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				envValDuration, err := time.ParseDuration(envVal)
 				if err == nil {
 					f.Value = envValDuration
+					break
+				}
 			}
 		}
 	}
@@ -362,13 +396,16 @@ func (f Float64Flag) String() string {
 
 func (f Float64Flag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
 				envValFloat, err := strconv.ParseFloat(envVal, 10)
 				if err == nil {
 					f.Value = float64(envValFloat)
 				}
 			}
 		}
+	}
 
 	eachName(f.Name, func(name string) {
 		set.Float64(name, f.Value, f.Usage)
@@ -404,7 +441,7 @@ func prefixedNames(fullName string) (prefixed string) {
 func withEnvHint(envVar, str string) string {
 	envText := ""
 	if envVar != "" {
-		envText = fmt.Sprintf(" [$%s]", envVar)
+		envText = fmt.Sprintf(" [$%s]", strings.Join(strings.Split(envVar, ","), ", $"))
 	}
 	return str + envText
 }

flag_test.go

@@ -54,7 +54,7 @@ func TestStringFlagHelpOutput(t *testing.T) {
 }
 
 func TestStringFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_FOO", "derp")
 	for _, test := range stringFlagTests {
 		flag := cli.StringFlag{Name: test.name, Value: test.value, EnvVar: "APP_FOO"}
@@ -106,7 +106,7 @@ func TestStringSliceFlagHelpOutput(t *testing.T) {
 }
 
 func TestStringSliceFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_QWWX", "11,4")
 	for _, test := range stringSliceFlagTests {
 		flag := cli.StringSliceFlag{Name: test.name, Value: test.value, EnvVar: "APP_QWWX"}
@@ -139,7 +139,7 @@ func TestIntFlagHelpOutput(t *testing.T) {
 }
 
 func TestIntFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAR", "2")
 	for _, test := range intFlagTests {
 		flag := cli.IntFlag{Name: test.name, EnvVar: "APP_BAR"}
@@ -172,7 +172,7 @@ func TestDurationFlagHelpOutput(t *testing.T) {
 }
 
 func TestDurationFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAR", "2h3m6s")
 	for _, test := range durationFlagTests {
 		flag := cli.DurationFlag{Name: test.name, EnvVar: "APP_BAR"}
@@ -212,7 +212,7 @@ func TestIntSliceFlagHelpOutput(t *testing.T) {
 }
 
 func TestIntSliceFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_SMURF", "42,3")
 	for _, test := range intSliceFlagTests {
 		flag := cli.IntSliceFlag{Name: test.name, Value: test.value, EnvVar: "APP_SMURF"}
@@ -245,7 +245,7 @@ func TestFloat64FlagHelpOutput(t *testing.T) {
 }
 
 func TestFloat64FlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAZ", "99.4")
 	for _, test := range float64FlagTests {
 		flag := cli.Float64Flag{Name: test.name, EnvVar: "APP_BAZ"}
@@ -280,7 +280,7 @@ func TestGenericFlagHelpOutput(t *testing.T) {
 }
 
 func TestGenericFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_ZAP", "3")
 	for _, test := range genericFlagTests {
 		flag := cli.GenericFlag{Name: test.name, EnvVar: "APP_ZAP"}
@@ -309,6 +309,7 @@ func TestParseMultiString(t *testing.T) {
 }
 
 func TestParseMultiStringFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_COUNT", "20")
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -325,6 +326,24 @@ func TestParseMultiStringFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiStringFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_COUNT", "20")
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.StringFlag{Name: "count, c", EnvVar: "COMPAT_COUNT,APP_COUNT"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.String("count") != "20" {
+				t.Errorf("main name not set")
+			}
+			if ctx.String("c") != "20" {
+				t.Errorf("short name not set")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiStringSlice(t *testing.T) {
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -342,6 +361,7 @@ func TestParseMultiStringSlice(t *testing.T) {
 }
 
 func TestParseMultiStringSliceFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_INTERVALS", "20,30,40")
 
 	(&cli.App{
@@ -359,6 +379,25 @@ func TestParseMultiStringSliceFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiStringSliceFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_INTERVALS", "20,30,40")
+
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.StringSliceFlag{Name: "intervals, i", Value: &cli.StringSlice{}, EnvVar: "COMPAT_INTERVALS,APP_INTERVALS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.StringSlice("intervals"), []string{"20", "30", "40"}) {
+				t.Errorf("main name not set from env")
+			}
+			if !reflect.DeepEqual(ctx.StringSlice("i"), []string{"20", "30", "40"}) {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiInt(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -377,6 +416,7 @@ func TestParseMultiInt(t *testing.T) {
 }
 
 func TestParseMultiIntFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_TIMEOUT_SECONDS", "10")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -394,6 +434,25 @@ func TestParseMultiIntFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiIntFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "10")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.IntFlag{Name: "timeout, t", EnvVar: "COMPAT_TIMEOUT_SECONDS,APP_TIMEOUT_SECONDS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Int("timeout") != 10 {
+				t.Errorf("main name not set")
+			}
+			if ctx.Int("t") != 10 {
+				t.Errorf("short name not set")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiIntSlice(t *testing.T) {
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -411,6 +470,7 @@ func TestParseMultiIntSlice(t *testing.T) {
 }
 
 func TestParseMultiIntSliceFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_INTERVALS", "20,30,40")
 
 	(&cli.App{
@@ -428,6 +488,25 @@ func TestParseMultiIntSliceFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiIntSliceFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_INTERVALS", "20,30,40")
+
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.IntSliceFlag{Name: "intervals, i", Value: &cli.IntSlice{}, EnvVar: "COMPAT_INTERVALS,APP_INTERVALS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.IntSlice("intervals"), []int{20, 30, 40}) {
+				t.Errorf("main name not set from env")
+			}
+			if !reflect.DeepEqual(ctx.IntSlice("i"), []int{20, 30, 40}) {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiFloat64(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -446,6 +525,7 @@ func TestParseMultiFloat64(t *testing.T) {
 }
 
 func TestParseMultiFloat64FromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -463,6 +543,25 @@ func TestParseMultiFloat64FromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiFloat64FromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.Float64Flag{Name: "timeout, t", EnvVar: "COMPAT_TIMEOUT_SECONDS,APP_TIMEOUT_SECONDS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Float64("timeout") != 15.5 {
+				t.Errorf("main name not set")
+			}
+			if ctx.Float64("t") != 15.5 {
+				t.Errorf("short name not set")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiBool(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -481,6 +580,7 @@ func TestParseMultiBool(t *testing.T) {
 }
 
 func TestParseMultiBoolFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_DEBUG", "1")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -498,6 +598,25 @@ func TestParseMultiBoolFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiBoolFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_DEBUG", "1")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.BoolFlag{Name: "debug, d", EnvVar: "COMPAT_DEBUG,APP_DEBUG"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Bool("debug") != true {
+				t.Errorf("main name not set from env")
+			}
+			if ctx.Bool("d") != true {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiBoolT(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -516,6 +635,7 @@ func TestParseMultiBoolT(t *testing.T) {
 }
 
 func TestParseMultiBoolTFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_DEBUG", "0")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -533,6 +653,25 @@ func TestParseMultiBoolTFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiBoolTFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_DEBUG", "0")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.BoolTFlag{Name: "debug, d", EnvVar: "COMPAT_DEBUG,APP_DEBUG"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.BoolT("debug") != false {
+				t.Errorf("main name not set from env")
+			}
+			if ctx.BoolT("d") != false {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 type Parser [2]string
 
 func (p *Parser) Set(value string) error {
@@ -569,6 +708,7 @@ func TestParseGeneric(t *testing.T) {
 }
 
 func TestParseGenericFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_SERVE", "20,30")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -585,3 +725,19 @@ func TestParseGenericFromEnv(t *testing.T) {
 	}
 	a.Run([]string{"run"})
 }
+
+func TestParseGenericFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_FOO", "99,2000")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.GenericFlag{Name: "foos", Value: &Parser{}, EnvVar: "COMPAT_FOO,APP_FOO"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.Generic("foos"), &Parser{"99", "2000"}) {
+				t.Errorf("value not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}