feat: add support for registry mirrors (#8244)

Signed-off-by: knqyf263 <knqyf263@gmail.com>
Co-authored-by: Teppei Fukuda <knqyf263@gmail.com>

Author: DmitriyLewen

docs/docs/configuration/others.md

@@ -117,3 +117,46 @@ The following example will fail when a critical vulnerability is found or the OS
 ```
 $ trivy image --exit-code 1 --exit-on-eol 1 --severity CRITICAL alpine:3.16.3
 ```
+
+## Mirror Registries
+
+!!! warning "EXPERIMENTAL"
+    This feature might change without preserving backwards compatibility.
+
+Trivy supports mirrors for [remote container images](../target/container_image.md#container-registry) and [databases](./db.md).
+
+To configure them, add a list of mirrors along with the host to the [trivy config file](../references/configuration/config-file.md#registry-options).
+
+!!! note
+    Use the `index.docker.io` host for images from `Docker Hub`, even if you don't use that prefix.
+
+Example for `index.docker.io`:
+```yaml
+registry:
+  mirrors:
+    index.docker.io:
+     - mirror.gcr.io
+```
+
+### Registry check procedure
+Trivy uses the following registry order to get the image:
+
+- mirrors in the same order as they are specified in the configuration file
+- source registry
+
+In cases where we can't get the image from the mirror registry (e.g. when authentication fails, image doesn't exist, etc.) - Trivy will check other mirrors (or the source registry if all mirrors have already been checked).
+
+Example:
+```yaml
+registry:
+  mirrors:
+    index.docker.io:
+     - mirror.with.bad.auth // We don't have credentials for this registry
+     - mirror.without.image // Registry doesn't have this image
+```
+
+When we want to get the image `alpine` with the settings above. The logic will be as follows:
+
+1. Try to get the image from `mirror.with.bad.auth/library/alpine`, but we get an error because there are no credentials for this registry.
+2. Try to get the image from `mirror.without.image/library/alpine`, but we get an error because this registry doesn't have this image (but most likely it will be an error about authorization).
+3. Get the image from `index.docker.io` (the original registry).

docs/docs/references/configuration/config-file.md

@@ -461,6 +461,8 @@ pkg:
 
 ```yaml
 registry:
+  mirrors:
+
   # Same as '--password'
   password: []
 

magefiles/docs.go

@@ -147,6 +147,14 @@ func writeFlagValue(val any, ind string, w *os.File) {
 		} else {
 			w.WriteString(" []\n")
 		}
+	case map[string][]string:
+		w.WriteString("\n")
+		for k, vv := range v {
+			fmt.Fprintf(w, "%s  %s:\n", ind, k)
+			for _, vvv := range vv {
+				fmt.Fprintf(w, "  %s - %s\n", ind, vvv)
+			}
+		}
 	case string:
 		fmt.Fprintf(w, " %q\n", v)
 	default:

pkg/fanal/types/image.go

@@ -81,6 +81,9 @@ type RegistryOptions struct {
 	// RegistryToken is a bearer token to be sent to a registry
 	RegistryToken string
 
+	// RegistryMirrors is a map of hosts with mirrors for them
+	RegistryMirrors map[string][]string
+
 	// SSL/TLS
 	Insecure bool
 

pkg/flag/options.go

@@ -30,7 +30,7 @@ import (
 )
 
 type FlagType interface {
-	int | string | []string | bool | time.Duration | float64
+	int | string | []string | bool | time.Duration | float64 | map[string][]string
 }
 
 type Flag[T FlagType] struct {
@@ -161,6 +161,8 @@ func (f *Flag[T]) cast(val any) any {
 		return cast.ToFloat64(val)
 	case time.Duration:
 		return cast.ToDuration(val)
+	case map[string][]string:
+		return cast.ToStringMapStringSlice(val)
 	case []string:
 		if s, ok := val.(string); ok && strings.Contains(s, ",") {
 			// Split environmental variables by comma as it is not done by viper.
@@ -467,11 +469,12 @@ func (o *Options) ScanOpts() types.ScanOptions {
 // RegistryOpts returns options for OCI registries
 func (o *Options) RegistryOpts() ftypes.RegistryOptions {
 	return ftypes.RegistryOptions{
-		Credentials:   o.Credentials,
-		RegistryToken: o.RegistryToken,
-		Insecure:      o.Insecure,
-		Platform:      o.Platform,
-		AWSRegion:     o.AWSOptions.Region,
+		Credentials:     o.Credentials,
+		RegistryToken:   o.RegistryToken,
+		Insecure:        o.Insecure,
+		Platform:        o.Platform,
+		AWSRegion:       o.AWSOptions.Region,
+		RegistryMirrors: o.RegistryMirrors,
 	}
 }
 

pkg/flag/registry_flags.go

@@ -31,26 +31,33 @@ var (
 		ConfigName: "registry.token",
 		Usage:      "registry token",
 	}
+	RegistryMirrorsFlag = Flag[map[string][]string]{
+		ConfigName: "registry.mirrors",
+		Usage:      "map of hosts and registries for them.",
+	}
 )
 
 type RegistryFlagGroup struct {
-	Username      *Flag[[]string]
-	Password      *Flag[[]string]
-	PasswordStdin *Flag[bool]
-	RegistryToken *Flag[string]
+	Username        *Flag[[]string]
+	Password        *Flag[[]string]
+	PasswordStdin   *Flag[bool]
+	RegistryToken   *Flag[string]
+	RegistryMirrors *Flag[map[string][]string]
 }
 
 type RegistryOptions struct {
-	Credentials   []types.Credential
-	RegistryToken string
+	Credentials     []types.Credential
+	RegistryToken   string
+	RegistryMirrors map[string][]string
 }
 
 func NewRegistryFlagGroup() *RegistryFlagGroup {
 	return &RegistryFlagGroup{
-		Username:      UsernameFlag.Clone(),
-		Password:      PasswordFlag.Clone(),
-		PasswordStdin: PasswordStdinFlag.Clone(),
-		RegistryToken: RegistryTokenFlag.Clone(),
+		Username:        UsernameFlag.Clone(),
+		Password:        PasswordFlag.Clone(),
+		PasswordStdin:   PasswordStdinFlag.Clone(),
+		RegistryToken:   RegistryTokenFlag.Clone(),
+		RegistryMirrors: RegistryMirrorsFlag.Clone(),
 	}
 }
 
@@ -64,6 +71,7 @@ func (f *RegistryFlagGroup) Flags() []Flagger {
 		f.Password,
 		f.PasswordStdin,
 		f.RegistryToken,
+		f.RegistryMirrors,
 	}
 }
 
@@ -97,7 +105,8 @@ func (f *RegistryFlagGroup) ToOptions() (RegistryOptions, error) {
 	}
 
 	return RegistryOptions{
-		Credentials:   credentials,
-		RegistryToken: f.RegistryToken.Value(),
+		Credentials:     credentials,
+		RegistryToken:   f.RegistryToken.Value(),
+		RegistryMirrors: f.RegistryMirrors.Value(),
 	}, nil
 }

pkg/remote/remote.go

@@ -3,9 +3,11 @@ package remote
 import (
 	"context"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/google/go-containerregistry/pkg/authn"
@@ -35,8 +37,14 @@ func Get(ctx context.Context, ref name.Reference, option types.RegistryOptions)
 		return nil, xerrors.Errorf("failed to create http transport: %w", err)
 	}
 
+	return tryWithMirrors(ref, option, func(r name.Reference) (*Descriptor, error) {
+		return tryGet(ctx, tr, r, option)
+	})
+}
+
+// tryGet checks all auth options and tries to get Descriptor.
+func tryGet(ctx context.Context, tr http.RoundTripper, ref name.Reference, option types.RegistryOptions) (*Descriptor, error) {
 	var errs error
-	// Try each authentication method until it succeeds
 	for _, authOpt := range authOptions(ctx, ref, option) {
 		remoteOpts := []remote.Option{
 			remote.WithTransport(tr),
@@ -67,8 +75,6 @@ func Get(ctx context.Context, ref name.Reference, option types.RegistryOptions)
 		}
 		return desc, nil
 	}
-
-	// No authentication succeeded
 	return nil, errs
 }
 
@@ -80,8 +86,49 @@ func Image(ctx context.Context, ref name.Reference, option types.RegistryOptions
 		return nil, xerrors.Errorf("failed to create http transport: %w", err)
 	}
 
+	return tryWithMirrors(ref, option, func(r name.Reference) (v1.Image, error) {
+		return tryImage(ctx, tr, r, option)
+	})
+}
+
+// tryWithMirrors handles common mirror logic for Get and Image functions
+func tryWithMirrors[T any](ref name.Reference, option types.RegistryOptions, fn func(name.Reference) (T, error)) (T, error) {
+	var zero T
+	mirrors, err := registryMirrors(ref, option)
+	if err != nil {
+		return zero, xerrors.Errorf("unable to parse mirrors: %w", err)
+	}
+
+	// Try each mirrors/host until it succeeds
+	var errs error
+	for _, r := range append(mirrors, ref) {
+		result, err := fn(r)
+		if err != nil {
+			var multiErr *multierror.Error
+			// All auth options failed, try the next mirror/host
+			if errors.As(err, &multiErr) {
+				errs = multierror.Append(errs, multiErr.Errors...)
+				continue
+			}
+			// Other errors
+			return zero, err
+		}
+
+		if ref.Context().RegistryStr() != r.Context().RegistryStr() {
+			log.WithPrefix("remote").Info("Using the mirror registry to get the image",
+				log.String("image", ref.String()), log.String("mirror", r.Context().RegistryStr()))
+		}
+		return result, nil
+	}
+
+	// No authentication for mirrors/host succeeded
+	return zero, errs
+}
+
+// tryImage checks all auth options and tries to get v1.Image.
+// If none of the auth options work - function returns multierrors for each auth option.
+func tryImage(ctx context.Context, tr http.RoundTripper, ref name.Reference, option types.RegistryOptions) (v1.Image, error) {
 	var errs error
-	// Try each authentication method until it succeeds
 	for _, authOpt := range authOptions(ctx, ref, option) {
 		remoteOpts := []remote.Option{
 			remote.WithTransport(tr),
@@ -92,10 +139,9 @@ func Image(ctx context.Context, ref name.Reference, option types.RegistryOptions
 			errs = multierror.Append(errs, err)
 			continue
 		}
+
 		return index, nil
 	}
-
-	// No authentication succeeded
 	return nil, errs
 }
 
@@ -126,6 +172,31 @@ func Referrers(ctx context.Context, d name.Digest, option types.RegistryOptions)
 	return nil, errs
 }
 
+// registryMirrors returns a list of mirrors for ref, obtained from options.RegistryMirrors
+// `go-containerregistry` doesn't support mirrors, so we need to handle them ourselves.
+// TODO: use `WithMirror` when `go-containerregistry` will support mirrors.
+// cf. https://github.com/google/go-containerregistry/pull/2010
+func registryMirrors(hostRef name.Reference, option types.RegistryOptions) ([]name.Reference, error) {
+	var mirrors []name.Reference
+
+	reg := hostRef.Context().RegistryStr()
+	if ms, ok := option.RegistryMirrors[reg]; ok {
+		for _, m := range ms {
+			var nameOpts []name.Option
+			if option.Insecure {
+				nameOpts = append(nameOpts, name.Insecure)
+			}
+			mirrorImageName := strings.Replace(hostRef.Name(), reg, m, 1)
+			ref, err := name.ParseReference(mirrorImageName, nameOpts...)
+			if err != nil {
+				return nil, xerrors.Errorf("unable to parse image from mirror registry: %w", err)
+			}
+			mirrors = append(mirrors, ref)
+		}
+	}
+	return mirrors, nil
+}
+
 func httpTransport(option types.RegistryOptions) (http.RoundTripper, error) {
 	d := &net.Dialer{
 		Timeout: 10 * time.Minute,