forked from TrueCloudLab/lego
288 lines
8.4 KiB
Go
288 lines
8.4 KiB
Go
// Package azure implements a DNS provider for solving the DNS-01 challenge using azure DNS.
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// Azure doesn't like trailing dots on domain names, most of the acme code does.
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package azure
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import (
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"context"
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"errors"
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"fmt"
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"io/ioutil"
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"net/http"
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"strings"
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"time"
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"github.com/Azure/azure-sdk-for-go/services/dns/mgmt/2017-09-01/dns"
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"github.com/Azure/go-autorest/autorest"
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"github.com/Azure/go-autorest/autorest/azure/auth"
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"github.com/Azure/go-autorest/autorest/to"
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"github.com/go-acme/lego/v3/challenge/dns01"
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"github.com/go-acme/lego/v3/platform/config/env"
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)
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const defaultMetadataEndpoint = "http://169.254.169.254"
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// Environment variables names.
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const (
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envNamespace = "AZURE_"
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EnvMetadataEndpoint = envNamespace + "METADATA_ENDPOINT"
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EnvSubscriptionID = envNamespace + "SUBSCRIPTION_ID"
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EnvResourceGroup = envNamespace + "RESOURCE_GROUP"
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EnvTenantID = envNamespace + "TENANT_ID"
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EnvClientID = envNamespace + "CLIENT_ID"
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EnvClientSecret = envNamespace + "CLIENT_SECRET"
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EnvTTL = envNamespace + "TTL"
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EnvPropagationTimeout = envNamespace + "PROPAGATION_TIMEOUT"
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EnvPollingInterval = envNamespace + "POLLING_INTERVAL"
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)
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// Config is used to configure the creation of the DNSProvider.
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type Config struct {
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// optional if using instance metadata service
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ClientID string
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ClientSecret string
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TenantID string
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SubscriptionID string
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ResourceGroup string
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MetadataEndpoint string
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PropagationTimeout time.Duration
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PollingInterval time.Duration
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TTL int
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HTTPClient *http.Client
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}
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// NewDefaultConfig returns a default configuration for the DNSProvider.
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func NewDefaultConfig() *Config {
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return &Config{
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TTL: env.GetOrDefaultInt(EnvTTL, 60),
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PropagationTimeout: env.GetOrDefaultSecond(EnvPropagationTimeout, 2*time.Minute),
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PollingInterval: env.GetOrDefaultSecond(EnvPollingInterval, 2*time.Second),
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MetadataEndpoint: env.GetOrFile(EnvMetadataEndpoint),
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}
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}
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// DNSProvider implements the challenge.Provider interface.
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type DNSProvider struct {
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config *Config
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authorizer autorest.Authorizer
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}
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// NewDNSProvider returns a DNSProvider instance configured for azure.
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// Credentials can be passed in the environment variables:
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// AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, AZURE_SUBSCRIPTION_ID, AZURE_TENANT_ID, AZURE_RESOURCE_GROUP
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// If the credentials are _not_ set via the environment,
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// then it will attempt to get a bearer token via the instance metadata service.
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// see: https://github.com/Azure/go-autorest/blob/v10.14.0/autorest/azure/auth/auth.go#L38-L42
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func NewDNSProvider() (*DNSProvider, error) {
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config := NewDefaultConfig()
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config.SubscriptionID = env.GetOrFile(EnvSubscriptionID)
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config.ResourceGroup = env.GetOrFile(EnvResourceGroup)
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config.ClientSecret = env.GetOrFile(EnvClientSecret)
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config.ClientID = env.GetOrFile(EnvClientID)
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config.TenantID = env.GetOrFile(EnvTenantID)
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return NewDNSProviderConfig(config)
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}
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// NewDNSProviderConfig return a DNSProvider instance configured for Azure.
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func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
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if config == nil {
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return nil, errors.New("azure: the configuration of the DNS provider is nil")
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}
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if config.HTTPClient == nil {
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config.HTTPClient = http.DefaultClient
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}
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authorizer, err := getAuthorizer(config)
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if err != nil {
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return nil, err
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}
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if config.SubscriptionID == "" {
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subsID, err := getMetadata(config, "subscriptionId")
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if err != nil {
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return nil, fmt.Errorf("azure: %w", err)
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}
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if subsID == "" {
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return nil, errors.New("azure: SubscriptionID is missing")
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}
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config.SubscriptionID = subsID
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}
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if config.ResourceGroup == "" {
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resGroup, err := getMetadata(config, "resourceGroupName")
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if err != nil {
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return nil, fmt.Errorf("azure: %w", err)
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}
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if resGroup == "" {
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return nil, errors.New("azure: ResourceGroup is missing")
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}
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config.ResourceGroup = resGroup
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}
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return &DNSProvider{config: config, authorizer: authorizer}, nil
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}
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// Timeout returns the timeout and interval to use when checking for DNS propagation.
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// Adjusting here to cope with spikes in propagation times.
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func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
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return d.config.PropagationTimeout, d.config.PollingInterval
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}
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// Present creates a TXT record to fulfill the dns-01 challenge.
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func (d *DNSProvider) Present(domain, token, keyAuth string) error {
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ctx := context.Background()
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fqdn, value := dns01.GetRecord(domain, keyAuth)
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zone, err := d.getHostedZoneID(ctx, fqdn)
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if err != nil {
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return fmt.Errorf("azure: %w", err)
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}
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rsc := dns.NewRecordSetsClient(d.config.SubscriptionID)
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rsc.Authorizer = d.authorizer
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relative := toRelativeRecord(fqdn, dns01.ToFqdn(zone))
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// Get existing record set
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rset, err := rsc.Get(ctx, d.config.ResourceGroup, zone, relative, dns.TXT)
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if err != nil {
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detailedError, ok := err.(autorest.DetailedError)
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if !ok || detailedError.StatusCode != http.StatusNotFound {
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return fmt.Errorf("azure: %w", err)
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}
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}
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// Construct unique TXT records using map
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uniqRecords := map[string]struct{}{value: {}}
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if rset.RecordSetProperties != nil && rset.TxtRecords != nil {
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for _, txtRecord := range *rset.TxtRecords {
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// Assume Value doesn't contain multiple strings
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if txtRecord.Value != nil && len(*txtRecord.Value) > 0 {
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uniqRecords[(*txtRecord.Value)[0]] = struct{}{}
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}
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}
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}
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var txtRecords []dns.TxtRecord
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for txt := range uniqRecords {
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txtRecords = append(txtRecords, dns.TxtRecord{Value: &[]string{txt}})
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}
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rec := dns.RecordSet{
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Name: &relative,
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RecordSetProperties: &dns.RecordSetProperties{
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TTL: to.Int64Ptr(int64(d.config.TTL)),
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TxtRecords: &txtRecords,
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},
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}
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_, err = rsc.CreateOrUpdate(ctx, d.config.ResourceGroup, zone, relative, dns.TXT, rec, "", "")
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if err != nil {
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return fmt.Errorf("azure: %w", err)
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}
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return nil
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}
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// CleanUp removes the TXT record matching the specified parameters.
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func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
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ctx := context.Background()
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fqdn, _ := dns01.GetRecord(domain, keyAuth)
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zone, err := d.getHostedZoneID(ctx, fqdn)
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if err != nil {
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return fmt.Errorf("azure: %w", err)
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}
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relative := toRelativeRecord(fqdn, dns01.ToFqdn(zone))
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rsc := dns.NewRecordSetsClient(d.config.SubscriptionID)
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rsc.Authorizer = d.authorizer
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_, err = rsc.Delete(ctx, d.config.ResourceGroup, zone, relative, dns.TXT, "")
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if err != nil {
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return fmt.Errorf("azure: %w", err)
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}
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return nil
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}
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// Checks that azure has a zone for this domain name.
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func (d *DNSProvider) getHostedZoneID(ctx context.Context, fqdn string) (string, error) {
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authZone, err := dns01.FindZoneByFqdn(fqdn)
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if err != nil {
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return "", err
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}
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dc := dns.NewZonesClient(d.config.SubscriptionID)
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dc.Authorizer = d.authorizer
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zone, err := dc.Get(ctx, d.config.ResourceGroup, dns01.UnFqdn(authZone))
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if err != nil {
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return "", err
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}
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// zone.Name shouldn't have a trailing dot(.)
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return to.String(zone.Name), nil
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}
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// Returns the relative record to the domain.
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func toRelativeRecord(domain, zone string) string {
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return dns01.UnFqdn(strings.TrimSuffix(domain, zone))
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}
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func getAuthorizer(config *Config) (autorest.Authorizer, error) {
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if config.ClientID != "" && config.ClientSecret != "" && config.TenantID != "" {
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credentialsConfig := auth.NewClientCredentialsConfig(config.ClientID, config.ClientSecret, config.TenantID)
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spToken, err := credentialsConfig.ServicePrincipalToken()
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if err != nil {
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return nil, fmt.Errorf("failed to get oauth token from client credentials: %v", err)
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}
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spToken.SetSender(config.HTTPClient)
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return autorest.NewBearerAuthorizer(spToken), nil
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}
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return auth.NewAuthorizerFromEnvironment()
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}
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// Fetches metadata from environment or he instance metadata service.
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// borrowed from https://github.com/Microsoft/azureimds/blob/master/imdssample.go
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func getMetadata(config *Config, field string) (string, error) {
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metadataEndpoint := config.MetadataEndpoint
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if len(metadataEndpoint) == 0 {
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metadataEndpoint = defaultMetadataEndpoint
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}
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resource := fmt.Sprintf("%s/metadata/instance/compute/%s", metadataEndpoint, field)
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req, err := http.NewRequest(http.MethodGet, resource, nil)
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if err != nil {
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return "", err
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}
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req.Header.Add("Metadata", "True")
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q := req.URL.Query()
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q.Add("format", "text")
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q.Add("api-version", "2017-12-01")
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req.URL.RawQuery = q.Encode()
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resp, err := config.HTTPClient.Do(req)
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if err != nil {
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return "", err
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}
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defer resp.Body.Close()
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respBody, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return "", err
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}
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return string(respBody), nil
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}
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