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Speed up VM create with work seeds

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Beat VM create wall time without changing VM semantics.

Generate a work-seed ext4 sidecar during image builds and rootfs rebuilds, then clone and resize that seed for each new VM instead of rebuilding /root from scratch. Plumb the new seed artifact through config, runtime metadata, store state, runtime-bundle defaults, doctor checks, and default-image reconciliation so older images still fall back cleanly.

Add a daemon TAP pool to keep idle bridge-attached devices warm, expose stage timing in lifecycle logs, add a create/SSH benchmark script plus Make target, and teach verify.sh that tap-pool-* devices are reusable capacity rather than cleanup leaks.

Validated with go test ./..., make build, ./verify.sh, and make bench-create ARGS="--runs 2".
This commit is contained in:
Thales Maciel 2026-03-18 21:22:12 -03:00
parent a14a80fd6b
commit c8d9a122f9
No known key found for this signature in database
GPG key ID: 33112E6833C34679
24 changed files with 695 additions and 44 deletions
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26
internal/config/config.go
View file

@ -4,6 +4,7 @@ import (
"errors"
"os"
"path/filepath"
"strings"
"time"
toml "github.com/pelletier/go-toml"
@ -22,6 +23,7 @@ type fileConfig struct {
NamegenPath string `toml:"namegen_path"`
CustomizeScript string `toml:"customize_script"`
VSockPingHelper string `toml:"vsock_ping_helper_path"`
DefaultWorkSeed string `toml:"default_work_seed"`
DefaultImageName string `toml:"default_image_name"`
DefaultRootfs string `toml:"default_rootfs"`
DefaultBaseRootfs string `toml:"default_base_rootfs"`
@ -35,6 +37,7 @@ type fileConfig struct {
BridgeName string `toml:"bridge_name"`
BridgeIP string `toml:"bridge_ip"`
CIDR string `toml:"cidr"`
TapPoolSize int `toml:"tap_pool_size"`
DefaultDNS string `toml:"default_dns"`
}
@ -47,6 +50,7 @@ func Load(layout paths.Layout) (model.DaemonConfig, error) {
BridgeName: model.DefaultBridgeName,
BridgeIP: model.DefaultBridgeIP,
CIDR: model.DefaultCIDR,
TapPoolSize: 4,
DefaultDNS: model.DefaultDNS,
DefaultImageName: "default",
}
@ -91,6 +95,9 @@ func Load(layout paths.Layout) (model.DaemonConfig, error) {
if file.VSockPingHelper != "" {
cfg.VSockPingHelperPath = file.VSockPingHelper
}
if file.DefaultWorkSeed != "" {
cfg.DefaultWorkSeed = file.DefaultWorkSeed
}
if file.DefaultImageName != "" {
cfg.DefaultImageName = file.DefaultImageName
}
@ -121,6 +128,9 @@ func Load(layout paths.Layout) (model.DaemonConfig, error) {
if file.CIDR != "" {
cfg.CIDR = file.CIDR
}
if file.TapPoolSize > 0 {
cfg.TapPoolSize = file.TapPoolSize
}
if file.DefaultDNS != "" {
cfg.DefaultDNS = file.DefaultDNS
}
@ -176,6 +186,9 @@ func applyRuntimeDefaults(cfg *model.DaemonConfig) error {
cfg.DefaultRootfs,
)
}
if cfg.DefaultWorkSeed == "" && cfg.DefaultRootfs != "" {
cfg.DefaultWorkSeed = firstExistingRuntimePath(associatedWorkSeedPath(cfg.DefaultRootfs))
}
return nil
}
@ -185,6 +198,7 @@ func applyBundleMetadataDefaults(cfg *model.DaemonConfig, runtimeDir string, met
cfg.NamegenPath = defaultRuntimePath(cfg.NamegenPath, runtimeDir, meta.NamegenPath)
cfg.CustomizeScript = defaultRuntimePath(cfg.CustomizeScript, runtimeDir, meta.CustomizeScript)
cfg.VSockPingHelperPath = defaultRuntimePath(cfg.VSockPingHelperPath, runtimeDir, meta.VSockPingHelperPath)
cfg.DefaultWorkSeed = defaultRuntimePath(cfg.DefaultWorkSeed, runtimeDir, meta.DefaultWorkSeed)
cfg.DefaultKernel = defaultRuntimePath(cfg.DefaultKernel, runtimeDir, meta.DefaultKernel)
cfg.DefaultInitrd = defaultRuntimePath(cfg.DefaultInitrd, runtimeDir, meta.DefaultInitrd)
cfg.DefaultModulesDir = defaultRuntimePath(cfg.DefaultModulesDir, runtimeDir, meta.DefaultModulesDir)
@ -199,6 +213,7 @@ func applyLegacyRuntimeDefaults(cfg *model.DaemonConfig) {
cfg.NamegenPath = defaultRuntimePath(cfg.NamegenPath, cfg.RuntimeDir, "namegen")
cfg.CustomizeScript = defaultRuntimePath(cfg.CustomizeScript, cfg.RuntimeDir, "customize.sh")
cfg.VSockPingHelperPath = defaultRuntimePath(cfg.VSockPingHelperPath, cfg.RuntimeDir, "banger-vsock-pingd")
cfg.DefaultWorkSeed = defaultRuntimePath(cfg.DefaultWorkSeed, cfg.RuntimeDir, "rootfs-docker.work-seed.ext4")
cfg.DefaultKernel = defaultRuntimePath(cfg.DefaultKernel, cfg.RuntimeDir, "wtf/root/boot/vmlinux-6.8.0-94-generic")
cfg.DefaultInitrd = defaultRuntimePath(cfg.DefaultInitrd, cfg.RuntimeDir, "wtf/root/boot/initrd.img-6.8.0-94-generic")
cfg.DefaultModulesDir = defaultRuntimePath(cfg.DefaultModulesDir, cfg.RuntimeDir, "wtf/root/lib/modules/6.8.0-94-generic")
@ -223,3 +238,14 @@ func firstExistingRuntimePath(paths ...string) string {
}
return ""
}
func associatedWorkSeedPath(rootfsPath string) string {
rootfsPath = strings.TrimSpace(rootfsPath)
if rootfsPath == "" {
return ""
}
if strings.HasSuffix(rootfsPath, ".ext4") {
return strings.TrimSuffix(rootfsPath, ".ext4") + ".work-seed.ext4"
}
return rootfsPath + ".work-seed"
}

9
internal/config/config_test.go
View file

@ -20,6 +20,7 @@ func TestLoadDerivesArtifactPathsFromRuntimeDir(t *testing.T) {
VSockPingHelperPath: "bin/banger-vsock-pingd",
DefaultPackages: "config/packages.apt",
DefaultRootfs: "images/rootfs-docker.ext4",
DefaultWorkSeed: "images/rootfs-docker.work-seed.ext4",
DefaultKernel: "kernels/vmlinux",
DefaultInitrd: "kernels/initrd.img",
DefaultModulesDir: "modules/current",
@ -32,6 +33,7 @@ func TestLoadDerivesArtifactPathsFromRuntimeDir(t *testing.T) {
meta.VSockPingHelperPath,
meta.DefaultPackages,
meta.DefaultRootfs,
meta.DefaultWorkSeed,
meta.DefaultKernel,
meta.DefaultInitrd,
filepath.Join(meta.DefaultModulesDir, "modules.dep"),
@ -79,6 +81,9 @@ func TestLoadDerivesArtifactPathsFromRuntimeDir(t *testing.T) {
if cfg.DefaultRootfs != filepath.Join(runtimeDir, meta.DefaultRootfs) {
t.Fatalf("DefaultRootfs = %q", cfg.DefaultRootfs)
}
if cfg.DefaultWorkSeed != filepath.Join(runtimeDir, meta.DefaultWorkSeed) {
t.Fatalf("DefaultWorkSeed = %q", cfg.DefaultWorkSeed)
}
if cfg.DefaultBaseRootfs != filepath.Join(runtimeDir, meta.DefaultRootfs) {
t.Fatalf("DefaultBaseRootfs = %q", cfg.DefaultBaseRootfs)
}
@ -106,6 +111,7 @@ func TestLoadFallsBackToLegacyRuntimeLayoutWithoutBundleMetadata(t *testing.T) {
"banger-vsock-pingd",
"packages.apt",
"rootfs-docker.ext4",
"rootfs-docker.work-seed.ext4",
"wtf/root/boot/vmlinux-6.8.0-94-generic",
"wtf/root/boot/initrd.img-6.8.0-94-generic",
"wtf/root/lib/modules/6.8.0-94-generic/modules.dep",
@ -131,6 +137,9 @@ func TestLoadFallsBackToLegacyRuntimeLayoutWithoutBundleMetadata(t *testing.T) {
if cfg.VSockPingHelperPath != filepath.Join(runtimeDir, "banger-vsock-pingd") {
t.Fatalf("VSockPingHelperPath = %q", cfg.VSockPingHelperPath)
}
if cfg.DefaultWorkSeed != filepath.Join(runtimeDir, "rootfs-docker.work-seed.ext4") {
t.Fatalf("DefaultWorkSeed = %q", cfg.DefaultWorkSeed)
}
if cfg.DefaultKernel != filepath.Join(runtimeDir, "wtf/root/boot/vmlinux-6.8.0-94-generic") {
t.Fatalf("DefaultKernel = %q", cfg.DefaultKernel)
}