Add cni config template support.

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

pkg/server/testing/fake_cni_plugin.go

@@ -21,7 +21,9 @@ import (
 )
 
 // FakeCNIPlugin is a fake plugin used for test.
-type FakeCNIPlugin struct{}
+type FakeCNIPlugin struct {
+	StatusErr error
+}
 
 // NewFakeCNIPlugin create a FakeCNIPlugin.
 func NewFakeCNIPlugin() *FakeCNIPlugin {
@@ -40,7 +42,7 @@ func (f *FakeCNIPlugin) Remove(id, path string, opts ...cni.NamespaceOpts) error
 
 // Status get the status of the plugin.
 func (f *FakeCNIPlugin) Status() error {
-	return nil
+	return f.StatusErr
 }
 
 // Load loads the network config.

pkg/server/update_runtime_config.go

@@ -17,13 +17,60 @@ limitations under the License.
 package server
 
 import (
-	"golang.org/x/net/context"
+	"os"
+	"path/filepath"
+	"text/template"
 
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/net/context"
 	runtime "k8s.io/kubernetes/pkg/kubelet/apis/cri/runtime/v1alpha2"
 )
 
+// cniConfigTemplate contains the values containerd will overwrite
+// in the cni config template.
+type cniConfigTemplate struct {
+	// PodCIDR is the cidr for pods on the node.
+	PodCIDR string
+}
+
+// cniConfigFileName is the name of cni config file generated by containerd.
+const cniConfigFileName = "10-containerd-net.conflist"
+
 // UpdateRuntimeConfig updates the runtime config. Currently only handles podCIDR updates.
-// TODO(random-liu): Figure out how to handle pod cidr in the cri plugin.
 func (c *criService) UpdateRuntimeConfig(ctx context.Context, r *runtime.UpdateRuntimeConfigRequest) (*runtime.UpdateRuntimeConfigResponse, error) {
+	podCIDR := r.GetRuntimeConfig().GetNetworkConfig().GetPodCidr()
+	if podCIDR == "" {
+		return &runtime.UpdateRuntimeConfigResponse{}, nil
+	}
+	confTemplate := c.config.NetworkPluginConfTemplate
+	if err := c.netPlugin.Status(); err == nil {
+		if confTemplate != "" {
+			logrus.Infof("Network plugin is ready, skip generating cni config from template %q", confTemplate)
+		}
+		return &runtime.UpdateRuntimeConfigResponse{}, nil
+	}
+	if confTemplate == "" {
+		logrus.Info("No cni config template is specified, wait for other system components to drop the config.")
+		return &runtime.UpdateRuntimeConfigResponse{}, nil
+	}
+	logrus.Infof("Generating cni config from template %q", confTemplate)
+	// generate cni config file from the template with updated pod cidr.
+	t, err := template.ParseFiles(confTemplate)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to parse cni config template %q", confTemplate)
+	}
+	if err := os.MkdirAll(c.config.NetworkPluginConfDir, 0755); err != nil {
+		return nil, errors.Wrapf(err, "failed to create cni config directory: %q", c.config.NetworkPluginConfDir)
+	}
+	confFile := filepath.Join(c.config.NetworkPluginConfDir, cniConfigFileName)
+	f, err := os.OpenFile(confFile, os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to open cni config file %q", confFile)
+	}
+	defer f.Close()
+	if err := t.Execute(f, cniConfigTemplate{PodCIDR: podCIDR}); err != nil {
+		return nil, errors.Wrapf(err, "failed to generate cni config file %q", confFile)
+	}
 	return &runtime.UpdateRuntimeConfigResponse{}, nil
 }

pkg/server/update_runtime_config_test.go

@@ -0,0 +1,141 @@
+/*
+Copyright 2018 The containerd Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/net/context"
+	runtime "k8s.io/kubernetes/pkg/kubelet/apis/cri/runtime/v1alpha2"
+
+	criconfig "github.com/containerd/cri/pkg/config"
+	servertesting "github.com/containerd/cri/pkg/server/testing"
+)
+
+func TestUpdateRuntimeConfig(t *testing.T) {
+	const (
+		testTemplate = `
+{
+	"name": "test-pod-network",
+	"cniVersion": "0.3.1",
+	"plugins": [
+	{
+		"type": "ptp",
+		"mtu": 1460,
+		"ipam": {
+			"type": "host-local",
+			"subnet": "{{.PodCIDR}}",
+			"routes": [
+			{"dst": "0.0.0.0/0"}
+			]
+		}
+	},
+	]
+}`
+		testCIDR = "10.0.0.0/24"
+		expected = `
+{
+	"name": "test-pod-network",
+	"cniVersion": "0.3.1",
+	"plugins": [
+	{
+		"type": "ptp",
+		"mtu": 1460,
+		"ipam": {
+			"type": "host-local",
+			"subnet": "10.0.0.0/24",
+			"routes": [
+			{"dst": "0.0.0.0/0"}
+			]
+		}
+	},
+	]
+}`
+	)
+
+	for name, test := range map[string]struct {
+		noTemplate      bool
+		emptyCIDR       bool
+		networkReady    bool
+		expectCNIConfig bool
+	}{
+		"should not generate cni config if cidr is empty": {
+			emptyCIDR:       true,
+			expectCNIConfig: false,
+		},
+		"should not generate cni config if template file is not specified": {
+			noTemplate:      true,
+			expectCNIConfig: false,
+		},
+		"should not generate cni config if network is ready": {
+			networkReady:    true,
+			expectCNIConfig: false,
+		},
+		"should generate cni config if template is specified and cidr is provided": {
+			expectCNIConfig: true,
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			testDir, err := ioutil.TempDir(os.TempDir(), "test-runtime-config")
+			require.NoError(t, err)
+			defer os.RemoveAll(testDir)
+			templateName := filepath.Join(testDir, "template")
+			err = ioutil.WriteFile(templateName, []byte(testTemplate), 0666)
+			require.NoError(t, err)
+			confDir := filepath.Join(testDir, "net.d")
+			confName := filepath.Join(confDir, cniConfigFileName)
+
+			c := newTestCRIService()
+			c.config.CniConfig = criconfig.CniConfig{
+				NetworkPluginConfDir:      confDir,
+				NetworkPluginConfTemplate: templateName,
+			}
+			req := &runtime.UpdateRuntimeConfigRequest{
+				RuntimeConfig: &runtime.RuntimeConfig{
+					NetworkConfig: &runtime.NetworkConfig{
+						PodCidr: testCIDR,
+					},
+				},
+			}
+			if test.noTemplate {
+				c.config.CniConfig.NetworkPluginConfTemplate = ""
+			}
+			if test.emptyCIDR {
+				req.RuntimeConfig.NetworkConfig.PodCidr = ""
+			}
+			if !test.networkReady {
+				c.netPlugin.(*servertesting.FakeCNIPlugin).StatusErr = errors.New("random error")
+			}
+			_, err = c.UpdateRuntimeConfig(context.Background(), req)
+			assert.NoError(t, err)
+			if !test.expectCNIConfig {
+				_, err := os.Stat(confName)
+				assert.Error(t, err)
+			} else {
+				got, err := ioutil.ReadFile(confName)
+				assert.NoError(t, err)
+				assert.Equal(t, expected, string(got))
+			}
+		})
+	}
+}