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// Copyright 2017-2019 Lei Ni (nilei81@gmail.com)
//
// 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 dragonboat
import (
"context"
"encoding/json"
"io/ioutil"
"net/http"
"os"
"path/filepath"
"time"
"github.com/lni/dragonboat/internal/settings"
"github.com/lni/dragonboat/internal/utils/envutil"
)
const (
// see
// http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html
ec2AZURL = "http://169.254.169.254/latest/meta-data/placement/availability-zone"
jsonRegionFileName = "dragonboat-region.json"
)
var (
// regionUnknown is the string value used to indicate region is unknown.
regionUnknown = settings.Soft.UnknownRegionName
)
func getRegion(ctx context.Context) (string, error) {
regionFuncs := []func(context.Context) (string, error){
ec2Region,
jsonRegion,
envRegion,
}
for _, f := range regionFuncs {
if r, err := f(ctx); err == nil && len(r) > 0 {
return r, nil
}
}
return regionUnknown, nil
}
func ec2Region(ctx context.Context) (string, error) {
req, err := http.NewRequest("GET", ec2AZURL, nil)
if err != nil {
return "", err
}
tctx, cancel := context.WithTimeout(ctx, 200*time.Millisecond)
defer cancel()
resp, err := http.DefaultClient.Do(req.WithContext(tctx))
if err != nil {
return "", err
}
defer func() {
if err = resp.Body.Close(); err != nil {
plog.Errorf("failed to close %v", err)
}
}()
data, err := ioutil.ReadAll(resp.Body)
if err != nil {
return "", err
}
return string(data), nil
}
type jsonRegionRec struct {
Region string
}
func jsonRegion(ctx context.Context) (string, error) {
directories := envutil.GetConfigDirs()
for _, dir := range directories {
fp := filepath.Join(dir, jsonRegionFileName)
f, err := os.Open(filepath.Clean(fp))
if err != nil {
continue
}
data, err := ioutil.ReadAll(f)
defer func() {
if err = f.Close(); err != nil {
plog.Errorf("failed to close file %v", err)
}
}()
if err == nil {
var jr jsonRegionRec
err = json.Unmarshal(data, &jr)
if err == nil {
return jr.Region, nil
}
}
}
return "", nil
}
func envRegion(ctx context.Context) (string, error) {
return envutil.GetStringEnvVarOrEmptyString("DRAGONBOAT_REGION"), nil
}