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https://github.com/siderolabs/talos.git
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908fd8789c
The new command `talosctl cgroups` fetches cgroups snapshot from the machine, parses it fully, enhances with additional information (e.g. resolves pod names), and presents a customizable view of cgroups configuration (e.g. limits) and current consumption. Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
80 lines
2.4 KiB
Go
80 lines
2.4 KiB
Go
// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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// Package zboot provides a function to extract the kernel from a Zboot image.
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package zboot
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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"os"
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"github.com/klauspost/compress/zstd"
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"golang.org/x/sys/unix"
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)
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// fileCloser is an interface that wraps the Close method.
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type fileCloser interface {
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Close() error
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}
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// Extract extracts the kernel from a Zboot image and returns a file descriptor of the extracted kernel.
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func Extract(kernel *os.File) (int, fileCloser, error) {
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// https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/tree/include/kexec-pe-zboot.h
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var peZbootheaderData [28]byte
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if _, err := io.ReadFull(kernel, peZbootheaderData[:]); err != nil {
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return 0, nil, err
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}
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// https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/firmware/efi/libstub/zboot-header.S
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// https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/include/linux/pe.h#n42
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if !bytes.Equal(peZbootheaderData[:2], []byte("MZ")) {
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return 0, nil, fmt.Errorf("invalid PE Zboot header")
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}
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// not a Zboot image, return
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if !bytes.Equal(peZbootheaderData[4:8], []byte("zimg")) {
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return int(kernel.Fd()), nil, nil
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}
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payloadOffset := binary.LittleEndian.Uint32(peZbootheaderData[8:12])
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payloadSize := binary.LittleEndian.Uint32(peZbootheaderData[12:16])
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if _, err := kernel.Seek(int64(payloadOffset), io.SeekStart); err != nil {
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return 0, nil, fmt.Errorf("failed to seek to kernel zstd data from vmlinuz.efi: %w", err)
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}
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z, err := zstd.NewReader(io.LimitReader(kernel, int64(payloadSize)))
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if err != nil {
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return 0, nil, fmt.Errorf("failed to create zstd reader: %w", err)
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}
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defer z.Close()
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fd, err := unix.MemfdCreate("vmlinux", 0)
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if err != nil {
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return 0, nil, fmt.Errorf("memfdCreate: %v", err)
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}
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kernelMemfd := os.NewFile(uintptr(fd), "vmlinux")
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if _, err := io.Copy(kernelMemfd, z); err != nil {
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kernelMemfd.Close() //nolint:errcheck
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return 0, nil, fmt.Errorf("failed to copy zstd data to memfd: %w", err)
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}
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if _, err := kernelMemfd.Seek(0, io.SeekStart); err != nil {
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kernelMemfd.Close() //nolint:errcheck
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return 0, nil, fmt.Errorf("failed to seek to start of memfd: %w", err)
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}
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return fd, kernelMemfd, nil
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}
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