dns_server.go

Documentation: github.com/chaos-mesh/chaos-mesh/pkg/chaosdaemon

     1  // Copyright 2021 Chaos Mesh Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  // http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  //
    15  
    16  package chaosdaemon
    17  
    18  import (
    19  	"context"
    20  	"fmt"
    21  	"net"
    22  
    23  	"github.com/golang/protobuf/ptypes/empty"
    24  	"github.com/pkg/errors"
    25  
    26  	"github.com/chaos-mesh/chaos-mesh/pkg/bpm"
    27  	pb "github.com/chaos-mesh/chaos-mesh/pkg/chaosdaemon/pb"
    28  	"github.com/chaos-mesh/chaos-mesh/pkg/chaosdaemon/util"
    29  )
    30  
    31  const (
    32  	// DNSServerConfFile is the default config file for DNS server
    33  	DNSServerConfFile = "/etc/resolv.conf"
    34  )
    35  
    36  var ErrInvalidDNSServer = errors.New("invalid DNS server address")
    37  
    38  func (s *DaemonServer) SetDNSServer(ctx context.Context,
    39  	req *pb.SetDNSServerRequest) (*empty.Empty, error) {
    40  	log := s.getLoggerFromContext(ctx)
    41  
    42  	log.Info("SetDNSServer", "request", req)
    43  	pid, err := s.crClient.GetPidFromContainerID(ctx, req.ContainerId)
    44  	if err != nil {
    45  		log.Error(err, "GetPidFromContainerID")
    46  		return nil, err
    47  	}
    48  
    49  	if req.Enable {
    50  		// set dns server to the chaos dns server's address
    51  
    52  		if net.ParseIP(req.DnsServer) == nil {
    53  			return nil, ErrInvalidDNSServer
    54  		}
    55  
    56  		// backup the /etc/resolv.conf
    57  		processBuilder := bpm.DefaultProcessBuilder("sh", "-c", fmt.Sprintf("ls %s.chaos.bak || cp %s %s.chaos.bak", DNSServerConfFile, DNSServerConfFile, DNSServerConfFile)).SetContext(ctx)
    58  		if req.EnterNS {
    59  			processBuilder = processBuilder.SetNS(pid, bpm.MountNS)
    60  		}
    61  
    62  		cmd := processBuilder.Build(ctx)
    63  		output, err := cmd.CombinedOutput()
    64  		if err != nil {
    65  			log.Error(err, "execute command error", "command", cmd.String(), "output", output)
    66  			return nil, util.EncodeOutputToError(output, err)
    67  		}
    68  		if len(output) != 0 {
    69  			log.Info("command output", "output", string(output))
    70  		}
    71  
    72  		// add chaos dns server to the first line of /etc/resolv.conf
    73  		// Note: can not replace the /etc/resolv.conf like `mv resolv_conf_dnschaos_temp resolv.conf`, will execute with error `Device or resource busy`
    74  		processBuilder = bpm.DefaultProcessBuilder("sh", "-c", fmt.Sprintf("cp %s /etc/resolv_conf_dnschaos_temp && sed -i 's/.*nameserver.*/nameserver %s/' /etc/resolv_conf_dnschaos_temp && cat /etc/resolv_conf_dnschaos_temp > %s && rm /etc/resolv_conf_dnschaos_temp", DNSServerConfFile, req.DnsServer, DNSServerConfFile)).SetContext(ctx)
    75  		if req.EnterNS {
    76  			processBuilder = processBuilder.SetNS(pid, bpm.MountNS)
    77  		}
    78  
    79  		cmd = processBuilder.Build(ctx)
    80  		output, err = cmd.CombinedOutput()
    81  		if err != nil {
    82  			log.Error(err, "execute command error", "command", cmd.String(), "output", output)
    83  			return nil, util.EncodeOutputToError(output, err)
    84  		}
    85  		if len(output) != 0 {
    86  			log.Info("command output", "output", string(output))
    87  		}
    88  	} else {
    89  		// recover the dns server's address
    90  		processBuilder := bpm.DefaultProcessBuilder("sh", "-c", fmt.Sprintf("ls %s.chaos.bak && cat %s.chaos.bak > %s || true", DNSServerConfFile, DNSServerConfFile, DNSServerConfFile)).SetContext(ctx)
    91  		if req.EnterNS {
    92  			processBuilder = processBuilder.SetNS(pid, bpm.MountNS)
    93  		}
    94  
    95  		cmd := processBuilder.Build(ctx)
    96  		output, err := cmd.CombinedOutput()
    97  		if err != nil {
    98  			log.Error(err, "execute command error", "command", cmd.String(), "output", output)
    99  			return nil, util.EncodeOutputToError(output, err)
   100  		}
   101  		if len(output) != 0 {
   102  			log.Info("command output", "output", string(output))
   103  		}
   104  	}
   105  
   106  	return &empty.Empty{}, nil
   107  }
   108