open-nomad/client/driver/args/args.go

53 lines
1.3 KiB
Go

package args
import (
"fmt"
"regexp"
"github.com/mattn/go-shellwords"
)
var (
envRe = regexp.MustCompile(`\$({[a-zA-Z0-9_]+}|[a-zA-Z0-9_]+)`)
)
// ParseAndReplace takes the user supplied args and a map of environment
// variables. It replaces any instance of an environment variable in the args
// with the actual value and does correct splitting of the arg list.
func ParseAndReplace(args string, env map[string]string) ([]string, error) {
// Set up parser.
p := shellwords.NewParser()
p.ParseEnv = false
p.ParseBacktick = false
parsed, err := p.Parse(args)
if err != nil {
return nil, fmt.Errorf("Couldn't parse args %v: %v", args, err)
}
replaced := make([]string, len(parsed))
for i, arg := range parsed {
replaced[i] = replaceEnv(arg, env)
}
return replaced, nil
}
// replaceEnv takes an arg and replaces all occurences of environment variables.
// If the variable is found in the passed map it is replaced, otherwise the
// original string is returned.
func replaceEnv(arg string, env map[string]string) string {
return envRe.ReplaceAllStringFunc(arg, func(arg string) string {
stripped := arg[1:]
if stripped[0] == '{' {
stripped = stripped[1 : len(stripped)-1]
}
if value, ok := env[stripped]; ok {
return value
}
return arg
})
}