proc_cgroups.go

Documentation: github.com/prometheus/procfs

     1  // Copyright 2021 The Prometheus Authors
     2  // Licensed under the Apache License, Version 2.0 (the "License");
     3  // you may not use this file except in compliance with the License.
     4  // You may obtain a copy of the License at
     5  //
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package procfs
    15  
    16  import (
    17  	"bufio"
    18  	"bytes"
    19  	"fmt"
    20  	"strconv"
    21  	"strings"
    22  
    23  	"github.com/prometheus/procfs/internal/util"
    24  )
    25  
    26  // CgroupSummary models one line from /proc/cgroups.
    27  // This file contains information about the controllers that are compiled into the kernel.
    28  //
    29  // Also see http://man7.org/linux/man-pages/man7/cgroups.7.html
    30  type CgroupSummary struct {
    31  	// The name of the controller. controller is also known as subsystem.
    32  	SubsysName string
    33  	// The unique ID of the cgroup hierarchy on which this controller is mounted.
    34  	Hierarchy int
    35  	// The number of control groups in this hierarchy using this controller.
    36  	Cgroups int
    37  	// This field contains the value 1 if this controller is enabled, or 0 if it has been disabled
    38  	Enabled int
    39  }
    40  
    41  // parseCgroupSummary parses each line of the /proc/cgroup file
    42  // Line format is `subsys_name	hierarchy	num_cgroups	enabled`.
    43  func parseCgroupSummaryString(CgroupSummaryStr string) (*CgroupSummary, error) {
    44  	var err error
    45  
    46  	fields := strings.Fields(CgroupSummaryStr)
    47  	// require at least 4 fields
    48  	if len(fields) < 4 {
    49  		return nil, fmt.Errorf("%w: 4+ fields required, found %d fields in cgroup info string: %s", ErrFileParse, len(fields), CgroupSummaryStr)
    50  	}
    51  
    52  	CgroupSummary := &CgroupSummary{
    53  		SubsysName: fields[0],
    54  	}
    55  	CgroupSummary.Hierarchy, err = strconv.Atoi(fields[1])
    56  	if err != nil {
    57  		return nil, fmt.Errorf("%w: Unable to parse hierarchy ID from %q", ErrFileParse, fields[1])
    58  	}
    59  	CgroupSummary.Cgroups, err = strconv.Atoi(fields[2])
    60  	if err != nil {
    61  		return nil, fmt.Errorf("%w: Unable to parse Cgroup Num from %q", ErrFileParse, fields[2])
    62  	}
    63  	CgroupSummary.Enabled, err = strconv.Atoi(fields[3])
    64  	if err != nil {
    65  		return nil, fmt.Errorf("%w: Unable to parse Enabled from %q", ErrFileParse, fields[3])
    66  	}
    67  	return CgroupSummary, nil
    68  }
    69  
    70  // parseCgroupSummary reads each line of the /proc/cgroup file.
    71  func parseCgroupSummary(data []byte) ([]CgroupSummary, error) {
    72  	var CgroupSummarys []CgroupSummary
    73  	scanner := bufio.NewScanner(bytes.NewReader(data))
    74  	for scanner.Scan() {
    75  		CgroupSummaryString := scanner.Text()
    76  		// ignore comment lines
    77  		if strings.HasPrefix(CgroupSummaryString, "#") {
    78  			continue
    79  		}
    80  		CgroupSummary, err := parseCgroupSummaryString(CgroupSummaryString)
    81  		if err != nil {
    82  			return nil, err
    83  		}
    84  		CgroupSummarys = append(CgroupSummarys, *CgroupSummary)
    85  	}
    86  
    87  	err := scanner.Err()
    88  	return CgroupSummarys, err
    89  }
    90  
    91  // CgroupSummarys returns information about current /proc/cgroups.
    92  func (fs FS) CgroupSummarys() ([]CgroupSummary, error) {
    93  	data, err := util.ReadFileNoStat(fs.proc.Path("cgroups"))
    94  	if err != nil {
    95  		return nil, err
    96  	}
    97  	return parseCgroupSummary(data)
    98  }
    99
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