adds hardcoded nameserver for testing dns config

ecs-agent/netlib/platform/managed_linux.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	goErr "errors"
 	"fmt"
+	"path/filepath"
 
 	"github.com/aws/amazon-ecs-agent/ecs-agent/acs/model/ecsacs"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/api/ecs/model/ecs"
@@ -16,7 +17,6 @@ import (
 	"github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/serviceconnect"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/status"
 	"github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/tasknetworkconfig"
-
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/pkg/errors"
 )
@@ -65,7 +65,44 @@ func (m *managedLinux) BuildTaskNetworkConfiguration(
 
 func (m *managedLinux) CreateDNSConfig(taskID string,
 	netNS *tasknetworkconfig.NetworkNamespace) error {
-	return m.common.createDNSConfig(taskID, true, netNS)
+	return m.createDNSConfig(taskID, netNS)
+}
+
+func (m *managedLinux) createDNSConfig(taskID string,
+	netNS *tasknetworkconfig.NetworkNamespace) error {
+	netNSName := netNS.Name
+	primaryIF := netNS.GetPrimaryInterface()
+
+	// Hard-code names servers (Temp fix)
+	data := m.common.nsUtil.BuildResolvConfig([]string{"8.8.8.8"},
+		[]string{"us-west-2.compute.internal"})
+
+	m.common.ioutil.WriteFile(
+		filepath.Join(networkConfigFileDirectory, netNSName, ResolveConfFileName),
+		[]byte(data),
+		networkConfigFileMode)
+
+	err := m.common.createHostnameFileForNetNS(netNSName, primaryIF)
+	if err != nil {
+		return errors.Wrap(err, "unable to create hostname file for netns")
+	}
+
+	err = m.common.createHostnameFileForDefaultNetNS()
+	if err != nil {
+		return errors.Wrap(err, "unable to verify the existence of /etc/hostname on the host")
+	}
+
+	err = m.common.createHostsFile(netNSName, primaryIF)
+	if err != nil {
+		return errors.Wrap(err, "unable to create hosts file for netns")
+	}
+
+	// Next, copy these files into a task volume, which can be used by containers as well, to
+	// configure their network.
+	if err := m.common.copyNetworkConfigFilesToTask(taskID, netNSName); err != nil {
+		return err
+	}
+	return nil
 }
 
 func (m *managedLinux) ConfigureInterface(

ecs-agent/netlib/platform/managed_linux_test.go

@@ -0,0 +1,99 @@
+//go:build !windows && unit
+// +build !windows,unit
+
+// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may
+// not use this file except in compliance with the License. A copy of the
+// License is located at
+//
+//	http://aws.amazon.com/apache2.0/
+//
+// or in the "license" file accompanying this file. This file 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 platform
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"testing"
+
+	mock_ecscni "github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/ecscni/mocks_nsutil"
+	"github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/networkinterface"
+	"github.com/aws/amazon-ecs-agent/ecs-agent/netlib/model/tasknetworkconfig"
+	mock_ioutilwrapper "github.com/aws/amazon-ecs-agent/ecs-agent/utils/ioutilwrapper/mocks"
+	mock_oswrapper "github.com/aws/amazon-ecs-agent/ecs-agent/utils/oswrapper/mocks"
+	mock_volume "github.com/aws/amazon-ecs-agent/ecs-agent/volume/mocks"
+
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestManagedLinux_CreateDNSConfig(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	netNSName := "netns-name"
+	netNSPath := "/etc/netns/" + netNSName
+	iface := getTestInterface()
+
+	netns := &tasknetworkconfig.NetworkNamespace{
+		Name:              netNSName,
+		Path:              netNSPath,
+		NetworkInterfaces: []*networkinterface.NetworkInterface{iface},
+	}
+	ioutil := mock_ioutilwrapper.NewMockIOUtil(ctrl)
+	nsUtil := mock_ecscni.NewMockNetNSUtil(ctrl)
+	osWrapper := mock_oswrapper.NewMockOS(ctrl)
+	mockFile := mock_oswrapper.NewMockFile(ctrl)
+	volumeAccessor := mock_volume.NewMockTaskVolumeAccessor(ctrl)
+	commonPlatform := &common{
+		ioutil:            ioutil,
+		nsUtil:            nsUtil,
+		os:                osWrapper,
+		dnsVolumeAccessor: volumeAccessor,
+	}
+
+	managedPlatform := &managedLinux{
+		common: *commonPlatform,
+	}
+
+	resolvData := fmt.Sprintf("nameserver %s\nsearch %s\n",
+		"8.8.8.8",
+		"us-west-2.compute.internal",
+	)
+	hostnameData := fmt.Sprintf("%s\n", iface.GetHostname())
+
+	// Test creation of hosts file.
+	hostsData := fmt.Sprintf("%s\n%s %s\n%s %s\n%s %s\n",
+		HostsLocalhostEntry,
+		ipv4Addr, dnsName,
+		addr, hostName,
+		addr2, hostName2,
+	)
+
+	taskID := "taskID"
+
+	// Creation of resolv.conf file.
+	nsUtil.EXPECT().BuildResolvConfig([]string{"8.8.8.8"}, []string{"us-west-2.compute.internal"}).Return(resolvData).Times(1)
+	ioutil.EXPECT().WriteFile(netNSPath+"/resolv.conf", []byte(resolvData), fs.FileMode(0644))
+
+	// Creation of hostname file.
+	ioutil.EXPECT().WriteFile(netNSPath+"/hostname", []byte(hostnameData), fs.FileMode(0644))
+	osWrapper.EXPECT().OpenFile("/etc/hostname", os.O_RDONLY|os.O_CREATE, fs.FileMode(0644)).Return(mockFile, nil).Times(1)
+	mockFile.EXPECT().Close().Times(1)
+	ioutil.EXPECT().WriteFile(netNSPath+"/hosts", []byte(hostsData), fs.FileMode(0644))
+
+	// CopyToVolume created files into task volume.
+	volumeAccessor.EXPECT().CopyToVolume(taskID, netNSPath+"/hosts", "hosts", fs.FileMode(0644)).Return(nil).Times(1)
+	volumeAccessor.EXPECT().CopyToVolume(taskID, netNSPath+"/resolv.conf", "resolv.conf", fs.FileMode(0644)).Return(nil).Times(1)
+	volumeAccessor.EXPECT().CopyToVolume(taskID, netNSPath+"/hostname", "hostname", fs.FileMode(0644)).Return(nil).Times(1)
+
+	err := managedPlatform.CreateDNSConfig(taskID, netns)
+	require.NoError(t, err)
+
+}