diff options
| -rw-r--r-- | README.md | 35 | ||||
| -rw-r--r-- | parse.go | 17 | ||||
| -rw-r--r-- | parse_test.go | 50 | ||||
| -rw-r--r-- | usage_test.go | 7 |
4 files changed, 107 insertions, 2 deletions
@@ -54,6 +54,41 @@ Input: src.txt Output: [x.out y.out z.out] ``` +### Environment variables + +```go +var args struct { + Workers int `arg:"env"` +} +arg.MustParse(&args) +fmt.Println("Workers:", args.Workers) +``` + +``` +$ WORKERS=4 ./example +Workers: 4 +``` + +``` +$ WORKERS=4 ./example --workers=6 +Workers: 6 +``` + +You can also override the name of the environment variable: + +```go +var args struct { + Workers int `arg:"env:NUM_WORKERS"` +} +arg.MustParse(&args) +fmt.Println("Workers:", args.Workers) +``` + +``` +$ NUM_WORKERS=4 ./example +Workers: 4 +``` + ### Usage strings ```go var args struct { @@ -18,6 +18,7 @@ type spec struct { required bool positional bool help string + env string wasPresent bool isBool bool } @@ -130,6 +131,13 @@ func NewParser(dests ...interface{}) (*Parser, error) { spec.positional = true case key == "help": spec.help = value + case key == "env": + // Use override name if provided + if value != "" { + spec.env = value + } else { + spec.env = strings.ToUpper(field.Name) + } default: return nil, fmt.Errorf("unrecognized tag '%s' on field %s", key, tag) } @@ -179,6 +187,15 @@ func process(specs []*spec, args []string) error { if spec.short != "" { optionMap[spec.short] = spec } + if spec.env != "" { + if value, found := os.LookupEnv(spec.env); found { + err := setScalar(spec.dest, value) + if err != nil { + return fmt.Errorf("error processing environment variable %s: %v", spec.env, err) + } + spec.wasPresent = true + } + } } // process each string from the command line diff --git a/parse_test.go b/parse_test.go index 7fca76a..f3e7350 100644 --- a/parse_test.go +++ b/parse_test.go @@ -357,3 +357,53 @@ func TestMustParse(t *testing.T) { assert.Equal(t, "bar", args.Foo) assert.NotNil(t, parser) } + +func TestEnvironmentVariable(t *testing.T) { + var args struct { + Foo string `arg:"env"` + } + os.Setenv("FOO", "bar") + os.Args = []string{"example"} + MustParse(&args) + assert.Equal(t, "bar", args.Foo) +} + +func TestEnvironmentVariableOverrideName(t *testing.T) { + var args struct { + Foo string `arg:"env:BAZ"` + } + os.Setenv("BAZ", "bar") + os.Args = []string{"example"} + MustParse(&args) + assert.Equal(t, "bar", args.Foo) +} + +func TestEnvironmentVariableOverrideArgument(t *testing.T) { + var args struct { + Foo string `arg:"env"` + } + os.Setenv("FOO", "bar") + os.Args = []string{"example", "--foo", "baz"} + MustParse(&args) + assert.Equal(t, "baz", args.Foo) +} + +func TestEnvironmentVariableError(t *testing.T) { + var args struct { + Foo int `arg:"env"` + } + os.Setenv("FOO", "bar") + os.Args = []string{"example"} + err := Parse(&args) + assert.Error(t, err) +} + +func TestEnvironmentVariableRequired(t *testing.T) { + var args struct { + Foo string `arg:"env,required"` + } + os.Setenv("FOO", "bar") + os.Args = []string{"example"} + MustParse(&args) + assert.Equal(t, "bar", args.Foo) +} diff --git a/usage_test.go b/usage_test.go index 2375e81..255018d 100644 --- a/usage_test.go +++ b/usage_test.go @@ -10,9 +10,9 @@ import ( ) func TestWriteUsage(t *testing.T) { - expectedUsage := "usage: example [--name NAME] [--value VALUE] [--verbose] [--dataset DATASET] [--optimize OPTIMIZE] [--ids IDS] INPUT [OUTPUT [OUTPUT ...]]\n" + expectedUsage := "usage: example [--name NAME] [--value VALUE] [--verbose] [--dataset DATASET] [--optimize OPTIMIZE] [--ids IDS] [--workers WORKERS] INPUT [OUTPUT [OUTPUT ...]]\n" - expectedHelp := `usage: example [--name NAME] [--value VALUE] [--verbose] [--dataset DATASET] [--optimize OPTIMIZE] [--ids IDS] INPUT [OUTPUT [OUTPUT ...]] + expectedHelp := `usage: example [--name NAME] [--value VALUE] [--verbose] [--dataset DATASET] [--optimize OPTIMIZE] [--ids IDS] [--workers WORKERS] INPUT [OUTPUT [OUTPUT ...]] positional arguments: input @@ -26,6 +26,8 @@ options: --optimize OPTIMIZE, -O OPTIMIZE optimization level --ids IDS Ids + --workers WORKERS, -w WORKERS + number of workers to start --help, -h display this help and exit ` var args struct { @@ -37,6 +39,7 @@ options: Dataset string `arg:"help:dataset to use"` Optimize int `arg:"-O,help:optimization level"` Ids []int64 `arg:"help:Ids"` + Workers int `arg:"-w,env:WORKERS,help:number of workers to start"` } args.Name = "Foo Bar" args.Value = 42 |