github.com/docker/docker@v299999999.0.0-20200612211812-aaf470eca7b5+incompatible/pkg/parsers/operatingsystem/operatingsystem_linux.go (about)

     1  // Package operatingsystem provides helper function to get the operating system
     2  // name for different platforms.
     3  package operatingsystem // import "github.com/docker/docker/pkg/parsers/operatingsystem"
     4  
     5  import (
     6  	"bufio"
     7  	"bytes"
     8  	"fmt"
     9  	"io/ioutil"
    10  	"os"
    11  	"strings"
    12  
    13  	shellwords "github.com/mattn/go-shellwords"
    14  )
    15  
    16  var (
    17  	// file to use to detect if the daemon is running in a container
    18  	proc1Cgroup = "/proc/1/cgroup"
    19  
    20  	// file to check to determine Operating System
    21  	etcOsRelease = "/etc/os-release"
    22  
    23  	// used by stateless systems like Clear Linux
    24  	altOsRelease = "/usr/lib/os-release"
    25  )
    26  
    27  // GetOperatingSystem gets the name of the current operating system.
    28  func GetOperatingSystem() (string, error) {
    29  	if prettyName, err := getValueFromOsRelease("PRETTY_NAME"); err != nil {
    30  		return "", err
    31  	} else if prettyName != "" {
    32  		return prettyName, nil
    33  	}
    34  
    35  	// If not set, defaults to PRETTY_NAME="Linux"
    36  	// c.f. http://www.freedesktop.org/software/systemd/man/os-release.html
    37  	return "Linux", nil
    38  }
    39  
    40  // GetOperatingSystemVersion gets the version of the current operating system, as a string.
    41  func GetOperatingSystemVersion() (string, error) {
    42  	return getValueFromOsRelease("VERSION_ID")
    43  }
    44  
    45  // parses the os-release file and returns the value associated with `key`
    46  func getValueFromOsRelease(key string) (string, error) {
    47  	osReleaseFile, err := os.Open(etcOsRelease)
    48  	if err != nil {
    49  		if !os.IsNotExist(err) {
    50  			return "", fmt.Errorf("Error opening %s: %v", etcOsRelease, err)
    51  		}
    52  		osReleaseFile, err = os.Open(altOsRelease)
    53  		if err != nil {
    54  			return "", fmt.Errorf("Error opening %s: %v", altOsRelease, err)
    55  		}
    56  	}
    57  	defer osReleaseFile.Close()
    58  
    59  	var value string
    60  	keyWithTrailingEqual := key + "="
    61  	scanner := bufio.NewScanner(osReleaseFile)
    62  	for scanner.Scan() {
    63  		line := scanner.Text()
    64  		if strings.HasPrefix(line, keyWithTrailingEqual) {
    65  			data := strings.SplitN(line, "=", 2)
    66  			values, err := shellwords.Parse(data[1])
    67  			if err != nil {
    68  				return "", fmt.Errorf("%s is invalid: %s", key, err.Error())
    69  			}
    70  			if len(values) != 1 {
    71  				return "", fmt.Errorf("%s needs to be enclosed by quotes if they have spaces: %s", key, data[1])
    72  			}
    73  			value = values[0]
    74  		}
    75  	}
    76  
    77  	return value, nil
    78  }
    79  
    80  // IsContainerized returns true if we are running inside a container.
    81  func IsContainerized() (bool, error) {
    82  	b, err := ioutil.ReadFile(proc1Cgroup)
    83  	if err != nil {
    84  		return false, err
    85  	}
    86  	for _, line := range bytes.Split(b, []byte{'\n'}) {
    87  		if len(line) > 0 && !bytes.HasSuffix(line, []byte(":/")) && !bytes.HasSuffix(line, []byte(":/init.scope")) {
    88  			return true, nil
    89  		}
    90  	}
    91  	return false, nil
    92  }