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package kernel
import (
"io/ioutil"
"path"
"strings"
"github.com/sirupsen/logrus"
)
// writeSystemProperty writes the value to a path under /proc/sys as determined from the key.
// For e.g. net.ipv4.ip_forward translated to /proc/sys/net/ipv4/ip_forward.
func writeSystemProperty(key, value string) error {
keyPath := strings.Replace(key, ".", "/", -1)
return ioutil.WriteFile(path.Join("/proc/sys", keyPath), []byte(value), 0644)
}
// readSystemProperty reads the value from the path under /proc/sys and returns it
func readSystemProperty(key string) (string, error) {
keyPath := strings.Replace(key, ".", "/", -1)
value, err := ioutil.ReadFile(path.Join("/proc/sys", keyPath))
if err != nil {
return "", err
}
return strings.TrimSpace(string(value)), nil
}
// ApplyOSTweaks applies the configuration values passed as arguments
func ApplyOSTweaks(osConfig map[string]*OSValue) {
for k, v := range osConfig {
// read the existing property from disk
oldv, err := readSystemProperty(k)
if err != nil {
logrus.WithError(err).Errorf("error reading the kernel parameter %s", k)
continue
}
if propertyIsValid(oldv, v.Value, v.CheckFn) {
// write new prop value to disk
if err := writeSystemProperty(k, v.Value); err != nil {
logrus.WithError(err).Errorf("error setting the kernel parameter %s = %s, (leaving as %s)", k, v.Value, oldv)
continue
}
logrus.Debugf("updated kernel parameter %s = %s (was %s)", k, v.Value, oldv)
}
}
}
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