107 lines
3.2 KiB
Go
107 lines
3.2 KiB
Go
// Package lightsail implements a DNS provider for solving the DNS-01 challenge
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// using AWS Lightsail DNS.
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package lightsail
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import (
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"math/rand"
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"time"
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"github.com/aws/aws-sdk-go/aws"
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"github.com/aws/aws-sdk-go/aws/client"
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"github.com/aws/aws-sdk-go/aws/request"
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"github.com/aws/aws-sdk-go/aws/session"
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"github.com/aws/aws-sdk-go/service/lightsail"
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"github.com/xenolf/lego/acmev2"
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)
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const (
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maxRetries = 5
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)
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// DNSProvider implements the acmev2.ChallengeProvider interface
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type DNSProvider struct {
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client *lightsail.Lightsail
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}
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// customRetryer implements the client.Retryer interface by composing the
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// DefaultRetryer. It controls the logic for retrying recoverable request
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// errors (e.g. when rate limits are exceeded).
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type customRetryer struct {
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client.DefaultRetryer
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}
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// RetryRules overwrites the DefaultRetryer's method.
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// It uses a basic exponential backoff algorithm that returns an initial
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// delay of ~400ms with an upper limit of ~30 seconds which should prevent
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// causing a high number of consecutive throttling errors.
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// For reference: Route 53 enforces an account-wide(!) 5req/s query limit.
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func (d customRetryer) RetryRules(r *request.Request) time.Duration {
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retryCount := r.RetryCount
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if retryCount > 7 {
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retryCount = 7
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}
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delay := (1 << uint(retryCount)) * (rand.Intn(50) + 200)
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return time.Duration(delay) * time.Millisecond
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}
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// NewDNSProvider returns a DNSProvider instance configured for the AWS
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// Lightsail service.
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//
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// AWS Credentials are automatically detected in the following locations
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// and prioritized in the following order:
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// 1. Environment variables: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY,
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// [AWS_SESSION_TOKEN], [DNS_ZONE]
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// 2. Shared credentials file (defaults to ~/.aws/credentials)
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// 3. Amazon EC2 IAM role
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//
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// public hosted zone via the FQDN.
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//
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// See also: https://github.com/aws/aws-sdk-go/wiki/configuring-sdk
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func NewDNSProvider() (*DNSProvider, error) {
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r := customRetryer{}
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r.NumMaxRetries = maxRetries
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config := request.WithRetryer(aws.NewConfig(), r)
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client := lightsail.New(session.New(config))
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return &DNSProvider{
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client: client,
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}, nil
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}
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// Present creates a TXT record using the specified parameters
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func (r *DNSProvider) Present(domain, token, keyAuth string) error {
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fqdn, value, _ := acmev2.DNS01Record(domain, keyAuth)
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value = `"` + value + `"`
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err := r.newTxtRecord(domain, fqdn, value)
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return err
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}
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// CleanUp removes the TXT record matching the specified parameters
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func (r *DNSProvider) CleanUp(domain, token, keyAuth string) error {
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fqdn, value, _ := acmev2.DNS01Record(domain, keyAuth)
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value = `"` + value + `"`
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params := &lightsail.DeleteDomainEntryInput{
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DomainName: aws.String(domain),
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DomainEntry: &lightsail.DomainEntry{
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Name: aws.String(fqdn),
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Type: aws.String("TXT"),
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Target: aws.String(value),
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},
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}
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_, err := r.client.DeleteDomainEntry(params)
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return err
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}
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func (r *DNSProvider) newTxtRecord(domain string, fqdn string, value string) error {
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params := &lightsail.CreateDomainEntryInput{
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DomainName: aws.String(domain),
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DomainEntry: &lightsail.DomainEntry{
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Name: aws.String(fqdn),
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Target: aws.String(value),
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Type: aws.String("TXT"),
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},
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}
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_, err := r.client.CreateDomainEntry(params)
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return err
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}
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