/
azure.go
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/
azure.go
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// Package azure implements a DNS provider for solving the DNS-01 challenge using azure DNS.
// Azure doesn't like trailing dots on domain names, most of the acme code does.
package azure
import (
"errors"
"fmt"
"io"
"net/http"
"net/url"
"time"
"github.com/Azure/go-autorest/autorest"
aazure "github.com/Azure/go-autorest/autorest/azure"
"github.com/Azure/go-autorest/autorest/azure/auth"
"github.com/go-acme/lego/v4/challenge"
"github.com/go-acme/lego/v4/platform/config/env"
"github.com/entrustcorporation/dv/providers/internal/errutils"
)
const defaultMetadataEndpoint = "http://169.254.169.254"
// Environment variables names.
const (
envNamespace = "AZURE_"
EnvEnvironment = envNamespace + "ENVIRONMENT"
EnvMetadataEndpoint = envNamespace + "METADATA_ENDPOINT"
EnvSubscriptionID = envNamespace + "SUBSCRIPTION_ID"
EnvResourceGroup = envNamespace + "RESOURCE_GROUP"
EnvTenantID = envNamespace + "TENANT_ID"
EnvClientID = envNamespace + "CLIENT_ID"
EnvClientSecret = envNamespace + "CLIENT_SECRET"
EnvZoneName = envNamespace + "ZONE_NAME"
EnvPrivateZone = envNamespace + "PRIVATE_ZONE"
EnvTTL = envNamespace + "TTL"
EnvPropagationTimeout = envNamespace + "PROPAGATION_TIMEOUT"
EnvPollingInterval = envNamespace + "POLLING_INTERVAL"
)
// Config is used to configure the creation of the DNSProvider.
type Config struct {
// optional if using instance metadata service
ClientID string
ClientSecret string
TenantID string
SubscriptionID string
ResourceGroup string
PrivateZone bool
MetadataEndpoint string
ResourceManagerEndpoint string
ActiveDirectoryEndpoint string
PropagationTimeout time.Duration
PollingInterval time.Duration
TTL int
HTTPClient *http.Client
}
// NewDefaultConfig returns a default configuration for the DNSProvider.
func NewDefaultConfig() *Config {
return &Config{
TTL: env.GetOrDefaultInt(EnvTTL, 60),
PropagationTimeout: env.GetOrDefaultSecond(EnvPropagationTimeout, 2*time.Minute),
PollingInterval: env.GetOrDefaultSecond(EnvPollingInterval, 2*time.Second),
MetadataEndpoint: env.GetOrFile(EnvMetadataEndpoint),
ResourceManagerEndpoint: aazure.PublicCloud.ResourceManagerEndpoint,
ActiveDirectoryEndpoint: aazure.PublicCloud.ActiveDirectoryEndpoint,
}
}
// DNSProvider implements the challenge.Provider interface.
type DNSProvider struct {
provider challenge.ProviderTimeout
}
// NewDNSProvider returns a DNSProvider instance configured for azure.
// Credentials can be passed in the environment variables:
// AZURE_ENVIRONMENT, AZURE_CLIENT_ID, AZURE_CLIENT_SECRET,
// AZURE_SUBSCRIPTION_ID, AZURE_TENANT_ID, AZURE_RESOURCE_GROUP
// If the credentials are _not_ set via the environment,
// then it will attempt to get a bearer token via the instance metadata service.
// see: https://github.com/Azure/go-autorest/blob/v10.14.0/autorest/azure/auth/auth.go#L38-L42
func NewDNSProvider() (*DNSProvider, error) {
config := NewDefaultConfig()
environmentName := env.GetOrFile(EnvEnvironment)
if environmentName != "" {
var environment aazure.Environment
switch environmentName {
case "china":
environment = aazure.ChinaCloud
case "german":
environment = aazure.GermanCloud
case "public":
environment = aazure.PublicCloud
case "usgovernment":
environment = aazure.USGovernmentCloud
default:
return nil, fmt.Errorf("azure: unknown environment %s", environmentName)
}
config.ResourceManagerEndpoint = environment.ResourceManagerEndpoint
config.ActiveDirectoryEndpoint = environment.ActiveDirectoryEndpoint
}
config.SubscriptionID = env.GetOrFile(EnvSubscriptionID)
config.ResourceGroup = env.GetOrFile(EnvResourceGroup)
config.ClientSecret = env.GetOrFile(EnvClientSecret)
config.ClientID = env.GetOrFile(EnvClientID)
config.TenantID = env.GetOrFile(EnvTenantID)
config.PrivateZone = env.GetOrDefaultBool(EnvPrivateZone, false)
return NewDNSProviderConfig(config)
}
// NewDNSProviderConfig return a DNSProvider instance configured for Azure.
func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
if config == nil {
return nil, errors.New("azure: the configuration of the DNS provider is nil")
}
if config.HTTPClient == nil {
config.HTTPClient = &http.Client{Timeout: 5 * time.Second}
}
authorizer, err := getAuthorizer(config)
if err != nil {
return nil, err
}
if config.SubscriptionID == "" {
subsID, err := getMetadata(config, "subscriptionId")
if err != nil {
return nil, fmt.Errorf("azure: %w", err)
}
if subsID == "" {
return nil, errors.New("azure: SubscriptionID is missing")
}
config.SubscriptionID = subsID
}
if config.ResourceGroup == "" {
resGroup, err := getMetadata(config, "resourceGroupName")
if err != nil {
return nil, fmt.Errorf("azure: %w", err)
}
if resGroup == "" {
return nil, errors.New("azure: ResourceGroup is missing")
}
config.ResourceGroup = resGroup
}
if config.PrivateZone {
return &DNSProvider{provider: &dnsProviderPrivate{config: config, authorizer: authorizer}}, nil
}
return &DNSProvider{provider: &dnsProviderPublic{config: config, authorizer: authorizer}}, 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.provider.Timeout()
}
// Present creates a TXT record to fulfill the dns-01 challenge.
func (d *DNSProvider) Present(domain, token, keyAuth string) error {
return d.provider.Present(domain, token, keyAuth)
}
// CleanUp removes the TXT record matching the specified parameters.
func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
return d.provider.CleanUp(domain, token, keyAuth)
}
func getAuthorizer(config *Config) (autorest.Authorizer, error) {
if config.ClientID != "" && config.ClientSecret != "" && config.TenantID != "" {
credentialsConfig := auth.ClientCredentialsConfig{
ClientID: config.ClientID,
ClientSecret: config.ClientSecret,
TenantID: config.TenantID,
Resource: config.ResourceManagerEndpoint,
AADEndpoint: config.ActiveDirectoryEndpoint,
}
spToken, err := credentialsConfig.ServicePrincipalToken()
if err != nil {
return nil, fmt.Errorf("failed to get oauth token from client credentials: %w", err)
}
spToken.SetSender(config.HTTPClient)
return autorest.NewBearerAuthorizer(spToken), nil
}
return auth.NewAuthorizerFromEnvironment()
}
// Fetches metadata from environment or he instance metadata service.
// borrowed from https://github.com/Microsoft/azureimds/blob/master/imdssample.go
func getMetadata(config *Config, field string) (string, error) {
metadataEndpoint := config.MetadataEndpoint
if metadataEndpoint == "" {
metadataEndpoint = defaultMetadataEndpoint
}
endpoint, err := url.JoinPath(metadataEndpoint, "metadata", "instance", "compute", field)
if err != nil {
return "", err
}
req, err := http.NewRequest(http.MethodGet, endpoint, nil)
if err != nil {
return "", err
}
req.Header.Set("Metadata", "True")
q := req.URL.Query()
q.Add("format", "text")
q.Add("api-version", "2017-12-01")
req.URL.RawQuery = q.Encode()
resp, err := config.HTTPClient.Do(req)
if err != nil {
return "", errutils.NewHTTPDoError(req, err)
}
defer func() { _ = resp.Body.Close() }()
raw, err := io.ReadAll(resp.Body)
if err != nil {
return "", errutils.NewReadResponseError(req, resp.StatusCode, err)
}
return string(raw), nil
}