Add wildcard mirror support.

Signed-off-by: Lantao Liu <lantaol@google.com>

docs/registry.md

@@ -13,12 +13,23 @@ To configure image registries create/modify the `/etc/containerd/config.toml` as
     endpoint = ["https://HostIP1:Port1"]
   [plugins.cri.registry.mirrors."test.insecure-registry.io"]
     endpoint = ["http://HostIP2:Port2"]
+  # wildcard matching is supported but not required.
+  [plugins.cri.registry.mirrors."*"]
+    endpoint = ["http://HostIP3:Port3"]
 ```
 
 The default configuration can be generated by `containerd config default > /etc/containerd/config.toml`.
 
 The endpoint is a list that can contain multiple image registry URLs split by commas. When pulling an image
-from a registry, containerd will try these endpoint URLs one by one, and use the first working one.
+from a registry, containerd will try these endpoint URLs one by one, and use the first working one. Please note
+that if the default registry endpoint is not already specified in the endpoint list, it will be automatically
+tried at the end with scheme `https` and path `v2`, e.g. `https://gcr.io/v2` for `gcr.io`.
+
+As an example, for the image `gcr.io/library/busybox:latest`, the endpoints are:
+* `gcr.io` is configured: endpoints for `gcr.io` + default endpoint `https://gcr.io/v2`.
+* `*` is configured, and `gcr.io` is not: endpoints for `*` + default
+  endpoint `https://gcr.io/v2`.
+* None of above is configured: default endpoint `https:/gcr.io/v2`.
 
 After modify this config, you need restart the `containerd` service.
 

pkg/server/image_pull.go

@@ -293,11 +293,9 @@ func (c *criService) registryHosts(auth *runtime.AuthConfig) docker.RegistryHost
 	return func(host string) ([]docker.RegistryHost, error) {
 		var registries []docker.RegistryHost
 
-		// Try mirrors in order, and then try the default registry if not tried.
+		endpoints, err := c.registryEndpoints(host)
-		endpoints, err := addDefaultEndpoint(
-			c.config.Registry.Mirrors[host].Endpoints, host)
 		if err != nil {
-			return nil, errors.Wrapf(err, "add default endpoint")
+			return nil, errors.Wrap(err, "get registry endpoints")
 		}
 		for _, e := range endpoints {
 			u, err := url.Parse(e)
@@ -347,9 +345,17 @@ func (c *criService) registryHosts(auth *runtime.AuthConfig) docker.RegistryHost
 	}
 }
 
-// addDefaultEndpoint add default registry endpoint if it does not
+// registryEndpoints returns endpoints for a given host.
-// exist in the passed-in endpoint list.
+// It adds default registry endpoint if it does not exist in the passed-in endpoint list.
-func addDefaultEndpoint(endpoints []string, host string) ([]string, error) {
+// It also supports wildcard host matching with `*`.
+func (c *criService) registryEndpoints(host string) ([]string, error) {
+	var endpoints []string
+	_, ok := c.config.Registry.Mirrors[host]
+	if ok {
+		endpoints = c.config.Registry.Mirrors[host].Endpoints
+	} else {
+		endpoints = c.config.Registry.Mirrors["*"].Endpoints
+	}
 	defaultHost, err := docker.DefaultHost(host)
 	if err != nil {
 		return nil, errors.Wrap(err, "get default host")

pkg/server/image_pull_test.go

@@ -22,6 +22,8 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	runtime "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
+
+	criconfig "github.com/containerd/cri/pkg/config"
 )
 
 func TestParseAuth(t *testing.T) {
@@ -103,16 +105,34 @@ func TestParseAuth(t *testing.T) {
 	}
 }
 
-func TestAddDefaultEndpoint(t *testing.T) {
+func TestRegistryEndpoints(t *testing.T) {
 	for desc, test := range map[string]struct {
-		endpoints []string
+		mirrors  map[string]criconfig.Mirror
-		host      string
+		host     string
-		expected  []string
+		expected []string
 	}{
-		"default endpoint not in list": {
+		"no mirror configured": {
-			endpoints: []string{
+			mirrors: map[string]criconfig.Mirror{
-				"https://registry-1.io",
+				"registry-1.io": {
-				"https://registry-2.io",
+					Endpoints: []string{
+						"https://registry-1.io",
+						"https://registry-2.io",
+					},
+				},
+			},
+			host: "registry-3.io",
+			expected: []string{
+				"https://registry-3.io",
+			},
+		},
+		"mirror configured": {
+			mirrors: map[string]criconfig.Mirror{
+				"registry-3.io": {
+					Endpoints: []string{
+						"https://registry-1.io",
+						"https://registry-2.io",
+					},
+				},
 			},
 			host: "registry-3.io",
 			expected: []string{
@@ -121,11 +141,50 @@ func TestAddDefaultEndpoint(t *testing.T) {
 				"https://registry-3.io",
 			},
 		},
-		"default endpoint in list with http": {
+		"wildcard mirror configured": {
-			endpoints: []string{
+			mirrors: map[string]criconfig.Mirror{
+				"*": {
+					Endpoints: []string{
+						"https://registry-1.io",
+						"https://registry-2.io",
+					},
+				},
+			},
+			host: "registry-3.io",
+			expected: []string{
 				"https://registry-1.io",
 				"https://registry-2.io",
-				"http://registry-3.io",
+				"https://registry-3.io",
+			},
+		},
+		"host should take precedence if both host and wildcard mirrors are configured": {
+			mirrors: map[string]criconfig.Mirror{
+				"*": {
+					Endpoints: []string{
+						"https://registry-1.io",
+					},
+				},
+				"registry-3.io": {
+					Endpoints: []string{
+						"https://registry-2.io",
+					},
+				},
+			},
+			host: "registry-3.io",
+			expected: []string{
+				"https://registry-2.io",
+				"https://registry-3.io",
+			},
+		},
+		"default endpoint in list with http": {
+			mirrors: map[string]criconfig.Mirror{
+				"registry-3.io": {
+					Endpoints: []string{
+						"https://registry-1.io",
+						"https://registry-2.io",
+						"http://registry-3.io",
+					},
+				},
 			},
 			host: "registry-3.io",
 			expected: []string{
@@ -135,10 +194,14 @@ func TestAddDefaultEndpoint(t *testing.T) {
 			},
 		},
 		"default endpoint in list with https": {
-			endpoints: []string{
+			mirrors: map[string]criconfig.Mirror{
-				"https://registry-1.io",
+				"registry-3.io": {
-				"https://registry-2.io",
+					Endpoints: []string{
-				"https://registry-3.io",
+						"https://registry-1.io",
+						"https://registry-2.io",
+						"https://registry-3.io",
+					},
+				},
 			},
 			host: "registry-3.io",
 			expected: []string{
@@ -148,10 +211,14 @@ func TestAddDefaultEndpoint(t *testing.T) {
 			},
 		},
 		"default endpoint in list with path": {
-			endpoints: []string{
+			mirrors: map[string]criconfig.Mirror{
-				"https://registry-1.io",
+				"registry-3.io": {
-				"https://registry-2.io",
+					Endpoints: []string{
-				"https://registry-3.io/path",
+						"https://registry-1.io",
+						"https://registry-2.io",
+						"https://registry-3.io/path",
+					},
+				},
 			},
 			host: "registry-3.io",
 			expected: []string{
@@ -162,7 +229,9 @@ func TestAddDefaultEndpoint(t *testing.T) {
 		},
 	} {
 		t.Logf("TestCase %q", desc)
-		got, err := addDefaultEndpoint(test.endpoints, test.host)
+		c := newTestCRIService()
+		c.config.Registry.Mirrors = test.mirrors
+		got, err := c.registryEndpoints(test.host)
 		assert.NoError(t, err)
 		assert.Equal(t, test.expected, got)
 	}