Andrey Smirnov 1edc08aa24 fix: correctly split lines with /dev/kmsg output
This fixes cases when large `log.Printf()` was simply lost as it exceeds
max line length (despite being multi-line string with each line below
1KB). Now console logging should be much more reliable.

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>
2020-01-27 05:15:09 -08:00

51 lines
1.2 KiB
Go

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
// Package kmsg provides access to kernel log.
package kmsg
import (
"fmt"
"io"
"log"
"os"
"path/filepath"
"golang.org/x/sys/unix"
"github.com/talos-systems/talos/pkg/constants"
)
// Setup configures the log package to write to the kernel ring buffer via
// /dev/kmsg.
func Setup(prefix string, withLogFile bool) error {
kmsg, err := os.OpenFile("/dev/kmsg", os.O_RDWR|unix.O_CLOEXEC|unix.O_NONBLOCK|unix.O_NOCTTY, 0666)
if err != nil {
return fmt.Errorf("failed to open /dev/kmsg: %w", err)
}
var writer io.Writer = &Writer{KmsgWriter: kmsg}
if withLogFile {
if err := os.MkdirAll(constants.DefaultLogPath, 0700); err != nil {
return err
}
logPath := filepath.Join(constants.DefaultLogPath, "machined.log")
f, err := os.OpenFile(logPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
if err != nil {
return fmt.Errorf("failed to open %s: %w", logPath, err)
}
writer = io.MultiWriter(writer, f)
}
log.SetOutput(writer)
log.SetPrefix(prefix + " ")
log.SetFlags(0)
return nil
}