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pkg/cfg: print help only when requested, and print it on stdout #1396

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Merged
merged 1 commit into from
Dec 13, 2019
Merged

pkg/cfg: print help only when requested, and print it on stdout #1396

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18 changes: 17 additions & 1 deletion pkg/cfg/files.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,9 @@ package cfg
import (
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"os"

"github.com/pkg/errors"
"gopkg.in/yaml.v2"
Expand Down Expand Up @@ -61,7 +63,21 @@ func dYAML(y []byte) Source {
func YAMLFlag(name, value, help string) Source {
return func(dst interface{}) error {
f := flag.String(name, value, help)
flag.Parse()

usage := flag.CommandLine.Usage
flag.CommandLine.Usage = func() { /* don't do anything by default, we will print usage ourselves, but only when requested. */ }

flag.CommandLine.Init(flag.CommandLine.Name(), flag.ContinueOnError)
err := flag.CommandLine.Parse(os.Args[1:])
if err == flag.ErrHelp {
// print available parameters to stdout, so that users can grep/less it easily
flag.CommandLine.SetOutput(os.Stdout)
usage()
os.Exit(2)
} else if err != nil {
fmt.Fprintln(flag.CommandLine.Output(), "Run with -help to get list of available parameters")
os.Exit(2)
}

if *f == "" {
f = nil
Expand Down