lego/providers/dns/lightsail/lightsail.go

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// Package lightsail implements a DNS provider for solving the DNS-01 challenge
// using AWS Lightsail DNS.
package lightsail
import (
"errors"
"fmt"
"math/rand"
"os"
"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/lightsail"
"github.com/xenolf/lego/acme"
"github.com/xenolf/lego/platform/config/env"
)
const (
maxRetries = 5
)
// 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 (c 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
}
// Config is used to configure the creation of the DNSProvider
type Config struct {
DNSZone string
Region string
PropagationTimeout time.Duration
PollingInterval time.Duration
}
// NewDefaultConfig returns a default configuration for the DNSProvider
func NewDefaultConfig() *Config {
return &Config{
DNSZone: os.Getenv("DNS_ZONE"),
PropagationTimeout: env.GetOrDefaultSecond("LIGHTSAIL_PROPAGATION_TIMEOUT", acme.DefaultPropagationTimeout),
PollingInterval: env.GetOrDefaultSecond("LIGHTSAIL_POLLING_INTERVAL", acme.DefaultPollingInterval),
Region: env.GetOrDefaultString("LIGHTSAIL_REGION", "us-east-1"),
}
}
// DNSProvider implements the acme.ChallengeProvider interface
type DNSProvider struct {
client *lightsail.Lightsail
config *Config
}
// NewDNSProvider returns a DNSProvider instance configured for the AWS Lightsail 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_SESSION_TOKEN], [DNS_ZONE], [LIGHTSAIL_REGION]
// 2. Shared credentials file (defaults to ~/.aws/credentials)
// 3. Amazon EC2 IAM role
//
// 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 return a DNSProvider instance configured for AWS Lightsail.
func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
if config == nil {
return nil, errors.New("lightsail: the configuration of the DNS provider is nil")
}
retryer := customRetryer{}
retryer.NumMaxRetries = maxRetries
conf := aws.NewConfig().WithRegion(config.Region)
sess, err := session.NewSession(request.WithRetryer(conf, retryer))
if err != nil {
return nil, err
}
return &DNSProvider{
config: config,
client: lightsail.New(sess),
}, nil
}
// Present creates a TXT record using the specified parameters
func (d *DNSProvider) Present(domain, token, keyAuth string) error {
fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
err := d.newTxtRecord(domain, fqdn, `"`+value+`"`)
if err != nil {
return fmt.Errorf("lightsail: %v", err)
}
return nil
}
// CleanUp removes the TXT record matching the specified parameters
func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
params := &lightsail.DeleteDomainEntryInput{
DomainName: aws.String(d.config.DNSZone),
DomainEntry: &lightsail.DomainEntry{
Name: aws.String(fqdn),
Type: aws.String("TXT"),
Target: aws.String(`"` + value + `"`),
},
}
_, err := d.client.DeleteDomainEntry(params)
if err != nil {
return fmt.Errorf("lightsail: %v", err)
}
return nil
}
// Timeout returns the timeout and interval to use when checking for DNS propagation.
// Adjusting here to cope with spikes in propagation times.
func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
return d.config.PropagationTimeout, d.config.PollingInterval
}
func (d *DNSProvider) newTxtRecord(domain string, fqdn string, value string) error {
params := &lightsail.CreateDomainEntryInput{
DomainName: aws.String(d.config.DNSZone),
DomainEntry: &lightsail.DomainEntry{
Name: aws.String(fqdn),
Target: aws.String(value),
Type: aws.String("TXT"),
},
}
_, err := d.client.CreateDomainEntry(params)
return err
}