gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/runsc/cmd/write_control.go (about)

     1  // Copyright 2022 The gVisor 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  package cmd
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  
    21  	"github.com/google/subcommands"
    22  	"gvisor.dev/gvisor/pkg/sentry/control"
    23  	"gvisor.dev/gvisor/runsc/cmd/util"
    24  	"gvisor.dev/gvisor/runsc/config"
    25  	"gvisor.dev/gvisor/runsc/container"
    26  	"gvisor.dev/gvisor/runsc/flag"
    27  )
    28  
    29  // WriteControl implements subcommands.Command for the "write-control" command.
    30  type WriteControl struct{}
    31  
    32  // Name implements subcommands.Command.Name.
    33  func (*WriteControl) Name() string {
    34  	return "write-control"
    35  }
    36  
    37  // Synopsis implements subcommands.Command.Synopsis.
    38  func (*WriteControl) Synopsis() string {
    39  	return "write a cgroups control value inside the container"
    40  }
    41  
    42  // Usage implements subcommands.Command.Usage.
    43  func (*WriteControl) Usage() string {
    44  	return `write-control <container-id> <controller> <cgroup-path> <control-value-name> <data-to-write>
    45  
    46  Where "<container-id>" is the name for the instance of the container,
    47  "<controller>" is the name of an active cgroupv1 controller, <cgroup-path> is
    48  the path to the cgroup to write and <control-value-name> is the name of the
    49  control file to write.
    50  
    51  EXAMPLE:
    52         # runsc write-control <container-id> memory / memory.limit_in_bytes 536870912
    53  `
    54  }
    55  
    56  // SetFlags implements subcommands.Command.SetFlags.
    57  func (r *WriteControl) SetFlags(f *flag.FlagSet) {}
    58  
    59  // Execute implements subcommands.Command.Execute.
    60  func (r *WriteControl) Execute(_ context.Context, f *flag.FlagSet, args ...any) subcommands.ExitStatus {
    61  	if f.NArg() < 5 {
    62  		f.Usage()
    63  		return subcommands.ExitUsageError
    64  	}
    65  
    66  	id := f.Arg(0)
    67  	conf := args[0].(*config.Config)
    68  
    69  	c, err := container.Load(conf.RootDir, container.FullID{ContainerID: id}, container.LoadOpts{SkipCheck: true})
    70  	if err != nil {
    71  		util.Fatalf("loading sandbox: %v", err)
    72  	}
    73  
    74  	err = c.Sandbox.CgroupsWriteControlFile(control.CgroupControlFile{
    75  		Controller: f.Arg(1),
    76  		Path:       f.Arg(2),
    77  		Name:       f.Arg(3),
    78  	}, f.Arg(4))
    79  	if err != nil {
    80  		fmt.Printf("ERROR: %s\n", err)
    81  		return subcommands.ExitFailure
    82  	}
    83  	return subcommands.ExitSuccess
    84  }