initrd/apply-config.go

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3.2 KiB
Go
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package main
import (
"os"
"path/filepath"
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"strconv"
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"strings"
"syscall"
"time"
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"github.com/rs/zerolog/log"
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yaml "gopkg.in/yaml.v2"
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"novit.tech/direktil/pkg/config/apply"
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)
var loopOffset = 0
func applyConfig(cfgPath string, bootMounted bool) (cfg *configV1) {
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cfgBytes, err := os.ReadFile(cfgPath)
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if err != nil {
fatalf("failed to read %s: %v", cfgPath, err)
}
cfg = &configV1{}
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if err := yaml.Unmarshal(cfgBytes, cfg); err != nil {
fatal("failed to load config: ", err)
}
// mount layers
if len(cfg.Layers) == 0 {
fatal("no layers configured!")
}
layersInMemory := paramBool("layers-in-mem", false)
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log.Info().Strs("layers", cfg.Layers).Bool("in-memory", layersInMemory).Msg("mounting layers")
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const layersInMemDir = "/layers-in-mem"
if layersInMemory {
mkdir(layersInMemDir, 0700)
mount("layers-mem", layersInMemDir, "tmpfs", 0, "")
}
lowers := make([]string, len(cfg.Layers))
for i, layer := range cfg.Layers {
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log := log.With().Str("layer", layer).Logger()
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path := layerPath(layer)
info, err := os.Stat(path)
if err != nil {
fatal(err)
}
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log.Info().Int64("size", info.Size()).Msg("layer found")
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if layersInMemory {
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log.Info().Msg("copying to memory")
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targetPath := filepath.Join(layersInMemDir, layer)
cp(path, targetPath)
path = targetPath
}
dir := "/layers/" + layer
lowers[i] = dir
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mountSquahfs(path, dir)
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}
// prepare system root
mount("mem", "/changes", "tmpfs", 0, "")
mkdir("/changes/workdir", 0755)
mkdir("/changes/upperdir", 0755)
mount("overlay", "/system", "overlay", rootMountFlags,
"lowerdir="+strings.Join(lowers, ":")+",upperdir=/changes/upperdir,workdir=/changes/workdir")
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// make root rshared (default in systemd, required by Kubernetes 1.10+)
// equivalent to "mount --make-rshared /"
// see kernel's Documentation/sharedsubtree.txt (search rshared)
if err := syscall.Mount("", "/system", "", syscall.MS_SHARED|syscall.MS_REC, ""); err != nil {
fatalf("FATAL: mount --make-rshared / failed: %v", err)
}
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if bootMounted {
if layersInMemory {
if err := syscall.Unmount("/boot", 0); err != nil {
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log.Warn().Err(err).Msg("failed to unmount /boot")
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time.Sleep(2 * time.Second)
}
} else {
mount("/boot", "/system/boot", "", syscall.MS_BIND, "")
}
}
// - write files
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apply.Files(cfg.Files, "/system")
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// - groups
for _, group := range cfg.Groups {
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logEvt := log.Info().Str("group", group.Name)
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opts := make([]string, 0)
opts = append(opts /* chroot */, "/system", "groupadd", "-r")
if group.Gid != 0 {
opts = append(opts, "-g", strconv.Itoa(group.Gid))
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logEvt.Int("gid", group.Gid)
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}
opts = append(opts, group.Name)
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logEvt.Msg("creating group")
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run("chroot", opts...)
}
// - user
for _, user := range cfg.Users {
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logEvt := log.Info().Str("user", user.Name)
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opts := make([]string, 0)
opts = append(opts /* chroot */, "/system", "useradd", "-r")
if user.Gid != 0 {
opts = append(opts, "-g", strconv.Itoa(user.Gid))
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logEvt.Int("gid", user.Gid)
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}
if user.Uid != 0 {
opts = append(opts, "-u", strconv.Itoa(user.Uid))
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logEvt.Int("uid", user.Uid)
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}
opts = append(opts, user.Name)
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logEvt.Msg("creating user")
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run("chroot", opts...)
}
return
}