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flag.go
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flag.go
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// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package flags
import (
"flag"
"fmt"
"log"
"net/url"
"os"
"strings"
"github.com/coreos/etcd/pkg/transport"
)
// DeprecatedFlag encapsulates a flag that may have been previously valid but
// is now deprecated. If a DeprecatedFlag is set, an error occurs.
type DeprecatedFlag struct {
Name string
}
func (f *DeprecatedFlag) Set(_ string) error {
return fmt.Errorf(`flag "-%s" is no longer supported.`, f.Name)
}
func (f *DeprecatedFlag) String() string {
return ""
}
// IgnoredFlag encapsulates a flag that may have been previously valid but is
// now ignored. If an IgnoredFlag is set, a warning is printed and
// operation continues.
type IgnoredFlag struct {
Name string
}
// IsBoolFlag is defined to allow the flag to be defined without an argument
func (f *IgnoredFlag) IsBoolFlag() bool {
return true
}
func (f *IgnoredFlag) Set(s string) error {
log.Printf(`WARNING: flag "-%s" is no longer supported - ignoring.`, f.Name)
return nil
}
func (f *IgnoredFlag) String() string {
return ""
}
// SetFlagsFromEnv parses all registered flags in the given flagset,
// and if they are not already set it attempts to set their values from
// environment variables. Environment variables take the name of the flag but
// are UPPERCASE, have the prefix "ETCD_", and any dashes are replaced by
// underscores - for example: some-flag => ETCD_SOME_FLAG
func SetFlagsFromEnv(fs *flag.FlagSet) error {
var err error
alreadySet := make(map[string]bool)
fs.Visit(func(f *flag.Flag) {
alreadySet[f.Name] = true
})
fs.VisitAll(func(f *flag.Flag) {
if !alreadySet[f.Name] {
key := "ETCD_" + strings.ToUpper(strings.Replace(f.Name, "-", "_", -1))
val := os.Getenv(key)
if val != "" {
if serr := fs.Set(f.Name, val); serr != nil {
err = fmt.Errorf("invalid value %q for %s: %v", val, key, serr)
}
}
}
})
return err
}
// URLsFromFlags decides what URLs should be using two different flags
// as datasources. The first flag's Value must be of type URLs, while
// the second must be of type IPAddressPort. If both of these flags
// are set, an error will be returned. If only the first flag is set,
// the underlying url.URL objects will be returned unmodified. If the
// second flag happens to be set, the underlying IPAddressPort will be
// converted to a url.URL and returned. The Scheme of the returned
// url.URL will be http unless the provided TLSInfo object is non-empty.
// If neither of the flags have been explicitly set, the default value
// of the first flag will be returned unmodified.
func URLsFromFlags(fs *flag.FlagSet, urlsFlagName string, addrFlagName string, tlsInfo transport.TLSInfo) ([]url.URL, error) {
visited := make(map[string]struct{})
fs.Visit(func(f *flag.Flag) {
visited[f.Name] = struct{}{}
})
_, urlsFlagIsSet := visited[urlsFlagName]
_, addrFlagIsSet := visited[addrFlagName]
if addrFlagIsSet {
if urlsFlagIsSet {
return nil, fmt.Errorf("Set only one of flags -%s and -%s", urlsFlagName, addrFlagName)
}
addr := *fs.Lookup(addrFlagName).Value.(*IPAddressPort)
addrURL := url.URL{Scheme: "http", Host: addr.String()}
if !tlsInfo.Empty() {
addrURL.Scheme = "https"
}
return []url.URL{addrURL}, nil
}
return []url.URL(*fs.Lookup(urlsFlagName).Value.(*URLsValue)), nil
}
func IsSet(fs *flag.FlagSet, name string) bool {
set := false
fs.Visit(func(f *flag.Flag) {
if f.Name == name {
set = true
}
})
return set
}