lego/providers/dns/route53/route53.go
2020-05-08 19:35:25 +02:00

298 lines
8.8 KiB
Go

// Package route53 implements a DNS provider for solving the DNS-01 challenge using AWS Route 53 DNS.
package route53
import (
"errors"
"fmt"
"math/rand"
"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/go-acme/lego/v3/challenge/dns01"
"github.com/go-acme/lego/v3/platform/config/env"
"github.com/go-acme/lego/v3/platform/wait"
)
// Environment variables names.
const (
envNamespace = "AWS_"
EnvAccessKeyID = envNamespace + "ACCESS_KEY_ID"
EnvSecretAccessKey = envNamespace + "SECRET_ACCESS_KEY"
EnvRegion = envNamespace + "REGION"
EnvHostedZoneID = envNamespace + "HOSTED_ZONE_ID"
EnvMaxRetries = envNamespace + "MAX_RETRIES"
EnvTTL = envNamespace + "TTL"
EnvPropagationTimeout = envNamespace + "PROPAGATION_TIMEOUT"
EnvPollingInterval = envNamespace + "POLLING_INTERVAL"
)
// Config is used to configure the creation of the DNSProvider.
type Config struct {
MaxRetries int
TTL int
PropagationTimeout time.Duration
PollingInterval time.Duration
HostedZoneID string
Client *route53.Route53
}
// NewDefaultConfig returns a default configuration for the DNSProvider.
func NewDefaultConfig() *Config {
return &Config{
MaxRetries: env.GetOrDefaultInt(EnvMaxRetries, 5),
TTL: env.GetOrDefaultInt(EnvTTL, 10),
PropagationTimeout: env.GetOrDefaultSecond(EnvPropagationTimeout, 2*time.Minute),
PollingInterval: env.GetOrDefaultSecond(EnvPollingInterval, 4*time.Second),
HostedZoneID: env.GetOrFile(EnvHostedZoneID),
}
}
// DNSProvider implements the challenge.Provider interface.
type DNSProvider struct {
client *route53.Route53
config *Config
}
// 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) {
return NewDNSProviderConfig(NewDefaultConfig())
}
// NewDNSProviderConfig takes a given config ans returns a custom configured DNSProvider instance.
func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
if config == nil {
return nil, errors.New("route53: the configuration of the Route53 DNS provider is nil")
}
if config.Client != nil {
return &DNSProvider{client: config.Client, config: config}, nil
}
retry := customRetryer{}
retry.NumMaxRetries = config.MaxRetries
sessionCfg := request.WithRetryer(aws.NewConfig(), retry)
sess, err := session.NewSessionWithOptions(session.Options{Config: *sessionCfg})
if err != nil {
return nil, err
}
cl := route53.New(sess)
return &DNSProvider{client: cl, config: config}, nil
}
// Timeout returns the timeout and interval to use when checking for DNS propagation.
func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
return d.config.PropagationTimeout, d.config.PollingInterval
}
// Present creates a TXT record using the specified parameters.
func (d *DNSProvider) Present(domain, token, keyAuth string) error {
fqdn, value := dns01.GetRecord(domain, keyAuth)
hostedZoneID, err := d.getHostedZoneID(fqdn)
if err != nil {
return fmt.Errorf("route53: failed to determine hosted zone ID: %w", err)
}
records, err := d.getExistingRecordSets(hostedZoneID, fqdn)
if err != nil {
return fmt.Errorf("route53: %w", err)
}
realValue := `"` + value + `"`
var found bool
for _, record := range records {
if aws.StringValue(record.Value) == realValue {
found = true
}
}
if !found {
records = append(records, &route53.ResourceRecord{Value: aws.String(realValue)})
}
recordSet := &route53.ResourceRecordSet{
Name: aws.String(fqdn),
Type: aws.String("TXT"),
TTL: aws.Int64(int64(d.config.TTL)),
ResourceRecords: records,
}
err = d.changeRecord(route53.ChangeActionUpsert, hostedZoneID, recordSet)
if err != nil {
return fmt.Errorf("route53: %w", err)
}
return nil
}
// CleanUp removes the TXT record matching the specified parameters.
func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
fqdn, _ := dns01.GetRecord(domain, keyAuth)
hostedZoneID, err := d.getHostedZoneID(fqdn)
if err != nil {
return fmt.Errorf("failed to determine Route 53 hosted zone ID: %w", err)
}
records, err := d.getExistingRecordSets(hostedZoneID, fqdn)
if err != nil {
return fmt.Errorf("route53: %w", err)
}
if len(records) == 0 {
return nil
}
recordSet := &route53.ResourceRecordSet{
Name: aws.String(fqdn),
Type: aws.String("TXT"),
TTL: aws.Int64(int64(d.config.TTL)),
ResourceRecords: records,
}
err = d.changeRecord(route53.ChangeActionDelete, hostedZoneID, recordSet)
if err != nil {
return fmt.Errorf("route53: %w", err)
}
return nil
}
func (d *DNSProvider) changeRecord(action, hostedZoneID string, recordSet *route53.ResourceRecordSet) error {
recordSetInput := &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 := d.client.ChangeResourceRecordSets(recordSetInput)
if err != nil {
return fmt.Errorf("failed to change record set: %w", err)
}
changeID := resp.ChangeInfo.Id
return wait.For("route53", d.config.PropagationTimeout, d.config.PollingInterval, func() (bool, error) {
reqParams := &route53.GetChangeInput{Id: changeID}
resp, err := d.client.GetChange(reqParams)
if err != nil {
return false, fmt.Errorf("failed to query change status: %w", err)
}
if aws.StringValue(resp.ChangeInfo.Status) == route53.ChangeStatusInsync {
return true, nil
}
return false, fmt.Errorf("unable to retrieve change: ID=%s", aws.StringValue(changeID))
})
}
func (d *DNSProvider) getExistingRecordSets(hostedZoneID string, fqdn string) ([]*route53.ResourceRecord, error) {
listInput := &route53.ListResourceRecordSetsInput{
HostedZoneId: aws.String(hostedZoneID),
StartRecordName: aws.String(fqdn),
StartRecordType: aws.String("TXT"),
}
recordSetsOutput, err := d.client.ListResourceRecordSets(listInput)
if err != nil {
return nil, err
}
if recordSetsOutput == nil {
return nil, nil
}
var records []*route53.ResourceRecord
for _, recordSet := range recordSetsOutput.ResourceRecordSets {
if aws.StringValue(recordSet.Name) == fqdn {
records = append(records, recordSet.ResourceRecords...)
}
}
return records, nil
}
func (d *DNSProvider) getHostedZoneID(fqdn string) (string, error) {
if d.config.HostedZoneID != "" {
return d.config.HostedZoneID, nil
}
authZone, err := dns01.FindZoneByFqdn(fqdn)
if err != nil {
return "", err
}
// .DNSName should not have a trailing dot
reqParams := &route53.ListHostedZonesByNameInput{
DNSName: aws.String(dns01.UnFqdn(authZone)),
}
resp, err := d.client.ListHostedZonesByName(reqParams)
if err != nil {
return "", err
}
var hostedZoneID string
for _, hostedZone := range resp.HostedZones {
// .Name has a trailing dot
if !aws.BoolValue(hostedZone.Config.PrivateZone) && aws.StringValue(hostedZone.Name) == authZone {
hostedZoneID = aws.StringValue(hostedZone.Id)
break
}
}
if len(hostedZoneID) == 0 {
return "", fmt.Errorf("zone %s not found for domain %s", authZone, fqdn)
}
if strings.HasPrefix(hostedZoneID, "/hostedzone/") {
hostedZoneID = strings.TrimPrefix(hostedZoneID, "/hostedzone/")
}
return hostedZoneID, nil
}