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lego/providers/dns/route53/route53.go
James Nugent b2aab0377c dns/route53: Allow specifying hosted zone ID (#345)
* dns/route53: Allow specifying hosted zone ID

This commit adds support for specifying hosted zone ID via the
environment variable AWS_HOSTED_ZONE_ID. If this is not specified, the
previous discovery process is used.

This is useful in environments where multiple hosted zones for the same
domain name are present in an account.

* dns/route53: Fix up getHostedZoneID method params

Now that getHostedZoneID is a method on the DNSProvider struct, there is
no reason for it to take the Route53 client as a parameter - we can
simply use the reference stored in the struct.
2017-07-17 21:50:53 +02:00

186 lines
5.2 KiB
Go

// Package route53 implements a DNS provider for solving the DNS-01 challenge
// using AWS Route 53 DNS.
package route53
import (
"fmt"
"math/rand"
"os"
"strings"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/client"
"github.com/aws/aws-sdk-go/aws/request"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/route53"
"github.com/xenolf/lego/acme"
)
const (
maxRetries = 5
route53TTL = 10
)
// DNSProvider implements the acme.ChallengeProvider interface
type DNSProvider struct {
client *route53.Route53
hostedZoneID string
}
// customRetryer implements the client.Retryer interface by composing the
// DefaultRetryer. It controls the logic for retrying recoverable request
// errors (e.g. when rate limits are exceeded).
type customRetryer struct {
client.DefaultRetryer
}
// RetryRules overwrites the DefaultRetryer's method.
// It uses a basic exponential backoff algorithm that returns an initial
// delay of ~400ms with an upper limit of ~30 seconds which should prevent
// causing a high number of consecutive throttling errors.
// For reference: Route 53 enforces an account-wide(!) 5req/s query limit.
func (d customRetryer) RetryRules(r *request.Request) time.Duration {
retryCount := r.RetryCount
if retryCount > 7 {
retryCount = 7
}
delay := (1 << uint(retryCount)) * (rand.Intn(50) + 200)
return time.Duration(delay) * time.Millisecond
}
// NewDNSProvider returns a DNSProvider instance configured for the AWS
// Route 53 service.
//
// AWS Credentials are automatically detected in the following locations
// and prioritized in the following order:
// 1. Environment variables: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY,
// AWS_REGION, [AWS_SESSION_TOKEN]
// 2. Shared credentials file (defaults to ~/.aws/credentials)
// 3. Amazon EC2 IAM role
//
// If AWS_HOSTED_ZONE_ID is not set, Lego tries to determine the correct
// public hosted zone via the FQDN.
//
// See also: https://github.com/aws/aws-sdk-go/wiki/configuring-sdk
func NewDNSProvider() (*DNSProvider, error) {
hostedZoneID := os.Getenv("AWS_HOSTED_ZONE_ID")
r := customRetryer{}
r.NumMaxRetries = maxRetries
config := request.WithRetryer(aws.NewConfig(), r)
client := route53.New(session.New(config))
return &DNSProvider{
client: client,
hostedZoneID: hostedZoneID,
}, nil
}
// Present creates a TXT record using the specified parameters
func (r *DNSProvider) Present(domain, token, keyAuth string) error {
fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
value = `"` + value + `"`
return r.changeRecord("UPSERT", fqdn, value, route53TTL)
}
// CleanUp removes the TXT record matching the specified parameters
func (r *DNSProvider) CleanUp(domain, token, keyAuth string) error {
fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
value = `"` + value + `"`
return r.changeRecord("DELETE", fqdn, value, route53TTL)
}
func (r *DNSProvider) changeRecord(action, fqdn, value string, ttl int) error {
hostedZoneID, err := r.getHostedZoneID(fqdn)
if err != nil {
return fmt.Errorf("Failed to determine Route 53 hosted zone ID: %v", err)
}
recordSet := newTXTRecordSet(fqdn, value, ttl)
reqParams := &route53.ChangeResourceRecordSetsInput{
HostedZoneId: aws.String(hostedZoneID),
ChangeBatch: &route53.ChangeBatch{
Comment: aws.String("Managed by Lego"),
Changes: []*route53.Change{
{
Action: aws.String(action),
ResourceRecordSet: recordSet,
},
},
},
}
resp, err := r.client.ChangeResourceRecordSets(reqParams)
if err != nil {
return fmt.Errorf("Failed to change Route 53 record set: %v", err)
}
statusID := resp.ChangeInfo.Id
return acme.WaitFor(120*time.Second, 4*time.Second, func() (bool, error) {
reqParams := &route53.GetChangeInput{
Id: statusID,
}
resp, err := r.client.GetChange(reqParams)
if err != nil {
return false, fmt.Errorf("Failed to query Route 53 change status: %v", err)
}
if *resp.ChangeInfo.Status == route53.ChangeStatusInsync {
return true, nil
}
return false, nil
})
}
func (r *DNSProvider) getHostedZoneID(fqdn string) (string, error) {
if r.hostedZoneID != "" {
return r.hostedZoneID, nil
}
authZone, err := acme.FindZoneByFqdn(fqdn, acme.RecursiveNameservers)
if err != nil {
return "", err
}
// .DNSName should not have a trailing dot
reqParams := &route53.ListHostedZonesByNameInput{
DNSName: aws.String(acme.UnFqdn(authZone)),
}
resp, err := r.client.ListHostedZonesByName(reqParams)
if err != nil {
return "", err
}
var hostedZoneID string
for _, hostedZone := range resp.HostedZones {
// .Name has a trailing dot
if !*hostedZone.Config.PrivateZone && *hostedZone.Name == authZone {
hostedZoneID = *hostedZone.Id
break
}
}
if len(hostedZoneID) == 0 {
return "", fmt.Errorf("Zone %s not found in Route 53 for domain %s", authZone, fqdn)
}
if strings.HasPrefix(hostedZoneID, "/hostedzone/") {
hostedZoneID = strings.TrimPrefix(hostedZoneID, "/hostedzone/")
}
return hostedZoneID, nil
}
func newTXTRecordSet(fqdn, value string, ttl int) *route53.ResourceRecordSet {
return &route53.ResourceRecordSet{
Name: aws.String(fqdn),
Type: aws.String("TXT"),
TTL: aws.Int64(int64(ttl)),
ResourceRecords: []*route53.ResourceRecord{
{Value: aws.String(value)},
},
}
}