lego/providers/dns/lightsail/lightsail.go
Derek Chen bacb545c7a Add DNS provider: Lightsail (#460)
* add lightsail dns provider

* fix lint errors

* update exoscale.go

* add the docs for lightsail provider
2018-02-18 08:27:58 -07:00

107 lines
3.2 KiB
Go

// Package lightsail implements a DNS provider for solving the DNS-01 challenge
// using AWS Lightsail DNS.
package lightsail
import (
"math/rand"
"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"
)
const (
maxRetries = 5
)
// DNSProvider implements the acme.ChallengeProvider interface
type DNSProvider struct {
client *lightsail.Lightsail
}
// 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
// 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]
// 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) {
r := customRetryer{}
r.NumMaxRetries = maxRetries
config := request.WithRetryer(aws.NewConfig(), r)
client := lightsail.New(session.New(config))
return &DNSProvider{
client: client,
}, 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 + `"`
err := r.newTxtRecord(domain, fqdn, value)
return err
}
// 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 + `"`
params := &lightsail.DeleteDomainEntryInput{
DomainName: aws.String(domain),
DomainEntry: &lightsail.DomainEntry{
Name: aws.String(fqdn),
Type: aws.String("TXT"),
Target: aws.String(value),
},
}
_, err := r.client.DeleteDomainEntry(params)
return err
}
func (r *DNSProvider) newTxtRecord(domain string, fqdn string, value string) error {
params := &lightsail.CreateDomainEntryInput{
DomainName: aws.String(domain),
DomainEntry: &lightsail.DomainEntry{
Name: aws.String(fqdn),
Target: aws.String(value),
Type: aws.String("TXT"),
},
}
_, err := r.client.CreateDomainEntry(params)
return err
}