github.com/Prakhar-Agarwal-byte/moby@v0.0.0-20231027092010-a14e3e8ab87e/libnetwork/osl/kernel/knobs_linux.go (about)

     1  package kernel
     2  
     3  import (
     4  	"context"
     5  	"os"
     6  	"path"
     7  	"strings"
     8  
     9  	"github.com/containerd/log"
    10  )
    11  
    12  // writeSystemProperty writes the value to a path under /proc/sys as determined from the key.
    13  // For e.g. net.ipv4.ip_forward translated to /proc/sys/net/ipv4/ip_forward.
    14  func writeSystemProperty(key, value string) error {
    15  	keyPath := strings.ReplaceAll(key, ".", "/")
    16  	return os.WriteFile(path.Join("/proc/sys", keyPath), []byte(value), 0o644)
    17  }
    18  
    19  // readSystemProperty reads the value from the path under /proc/sys and returns it
    20  func readSystemProperty(key string) (string, error) {
    21  	keyPath := strings.ReplaceAll(key, ".", "/")
    22  	value, err := os.ReadFile(path.Join("/proc/sys", keyPath))
    23  	if err != nil {
    24  		return "", err
    25  	}
    26  	return strings.TrimSpace(string(value)), nil
    27  }
    28  
    29  // ApplyOSTweaks applies the configuration values passed as arguments
    30  func ApplyOSTweaks(osConfig map[string]*OSValue) {
    31  	for k, v := range osConfig {
    32  		// read the existing property from disk
    33  		oldv, err := readSystemProperty(k)
    34  		if err != nil {
    35  			log.G(context.TODO()).WithError(err).Errorf("error reading the kernel parameter %s", k)
    36  			continue
    37  		}
    38  
    39  		if propertyIsValid(oldv, v.Value, v.CheckFn) {
    40  			// write new prop value to disk
    41  			if err := writeSystemProperty(k, v.Value); err != nil {
    42  				log.G(context.TODO()).WithError(err).Errorf("error setting the kernel parameter %s = %s, (leaving as %s)", k, v.Value, oldv)
    43  				continue
    44  			}
    45  			log.G(context.TODO()).Debugf("updated kernel parameter %s = %s (was %s)", k, v.Value, oldv)
    46  		}
    47  	}
    48  }