[CRIU] [PATCH] phaul: Go library for live migration
Andrei Vagin
avagin at virtuozzo.com
Mon Mar 13 11:34:31 PDT 2017
Applied. Thanks. Could you add the test to scripts/travis/travis-tests?
On Thu, Feb 16, 2017 at 03:06:11PM +0300, Pavel Emelyanov wrote:
> The API is as simple as
>
> srv := MakePhaulServer(config)
> cln := MakePhaulClient(local, remote, config)
> cln.Migrate()
>
> * config is the PhaulConfig struct that contains pid to migrate,
> memory transfer channel (file descriptor) that phaul can use
> to send/receive memory and path to existing directory where
> phaul can put intermediate files and images.
>
> * local is PhaulLocal interface with (for now) the single method
> - DumpCopyRestore(): method that phaul calls when it's time
> to do engine-specific dump, images copy and restore on
> the destination side.
>
> Few words about the latter -- we've learned, that different
> engines have their own way to call CRIU to dump a container,
> so phaul, instead of dumping one by its own, lets the caller
> do it. To keep-up with pre-dump stuff, the client should
> not forget to do three things:
>
> - set the TrackMem option to true
> - set the ParentImg to the passed value
> - set the Ps (page server) channel with 'config.Memfd'
>
> The criu object is passed here as well, so that caller can
> call Dump() on it (once we have keep_open support in libcriu
> this will help to avoid additional criu execve).
>
> The method also should handle the PostDump notification and
> do images-copy and restore in it. Not sure how to wrap this
> into phaul better.
>
> * remote is PhaulRemote interface whose method should be called
> on the dst side on the PhaulServer object using whatever RPC
> the caller finds acceptable.
>
> As a demonstration the src/test/main.go example is attached. To
> see how it goes 'make' it, then start the 'piggie $outfile'
> proggie and run 'test $pid' command. The piggie will be, well,
> live migrated locally :) i.e. will appear as a process with
> different pid (it lives in a pid namespace).
>
> Changes since v2:
>
> * Reworked the API onto local/remote/config scheme
> * Added ability to configure diretory for images
> * Re-used server side Criu object for final restore
>
> Changes since v1:
>
> * Supported keep_open-s for pre-dumps
> * Added code comments about interface
> * Simplified the example code
>
> Further plans for this are
>
> - move py p.haul to use this compiled library
> - add post-copy (lazy pages) support (with Mike help)
> - add image-cache and image-proxy (with Ridrigo help)
> - add API/framwork for FS migration
>
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
> ---
> phaul/.gitignore | 1 +
> phaul/Makefile | 11 +++
> phaul/piggie.c | 57 ++++++++++++++
> phaul/src/phaul/api.go | 52 +++++++++++++
> phaul/src/phaul/client.go | 130 ++++++++++++++++++++++++++++++++
> phaul/src/phaul/images.go | 41 ++++++++++
> phaul/src/phaul/server.go | 73 ++++++++++++++++++
> phaul/src/phaul/stats.go | 31 ++++++++
> phaul/src/test/main.go | 188 ++++++++++++++++++++++++++++++++++++++++++++++
> 9 files changed, 584 insertions(+)
> create mode 100644 phaul/.gitignore
> create mode 100644 phaul/Makefile
> create mode 100644 phaul/piggie.c
> create mode 100644 phaul/src/phaul/api.go
> create mode 100644 phaul/src/phaul/client.go
> create mode 100644 phaul/src/phaul/images.go
> create mode 100644 phaul/src/phaul/server.go
> create mode 100644 phaul/src/phaul/stats.go
> create mode 100644 phaul/src/test/main.go
>
> diff --git a/phaul/.gitignore b/phaul/.gitignore
> new file mode 100644
> index 0000000..d8d94a2
> --- /dev/null
> +++ b/phaul/.gitignore
> @@ -0,0 +1 @@
> +src/stats/stats.pb.go
> diff --git a/phaul/Makefile b/phaul/Makefile
> new file mode 100644
> index 0000000..7e83ba2
> --- /dev/null
> +++ b/phaul/Makefile
> @@ -0,0 +1,11 @@
> +all: test piggie
> +
> +test: stats
> + GOPATH=$(shell pwd):$(shell pwd)/../lib/go/:/usr/share/gocode go build -o test test
> +
> +stats:
> + mkdir -p src/stats/
> + protoc --go_out=src/stats/ --proto_path=../images/ ../images/stats.proto
> +
> +piggie: piggie.c
> + gcc piggie.c -o piggie
> diff --git a/phaul/piggie.c b/phaul/piggie.c
> new file mode 100644
> index 0000000..1dc0801
> --- /dev/null
> +++ b/phaul/piggie.c
> @@ -0,0 +1,57 @@
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <signal.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <fcntl.h>
> +#include <sched.h>
> +
> +#define STKS (4*4096)
> +
> +#ifndef CLONE_NEWPID
> +#define CLONE_NEWPID 0x20000000
> +#endif
> +
> +static int do_test(void *logf)
> +{
> + int fd, i = 0;
> +
> + setsid();
> +
> + close(0);
> + close(1);
> + close(2);
> +
> + fd = open("/dev/null", O_RDONLY);
> + if (fd != 0) {
> + dup2(fd, 0);
> + close(fd);
> + }
> +
> + fd = open(logf, O_WRONLY | O_TRUNC | O_CREAT, 0600);
> + dup2(fd, 1);
> + dup2(fd, 2);
> + if (fd != 1 && fd != 2)
> + close(fd);
> +
> + while (1) {
> + sleep(1);
> + printf("%d\n", i++);
> + fflush(stdout);
> + }
> +
> + return 0;
> +}
> +
> +int main(int argc, char **argv)
> +{
> + int pid;
> + void *stk;
> +
> + stk = mmap(NULL, STKS, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANON | MAP_GROWSDOWN, 0, 0);
> + pid = clone(do_test, stk + STKS, SIGCHLD | CLONE_NEWPID, argv[1]);
> + printf("Child forked, pid %d\n", pid);
> +
> + return 0;
> +}
> diff --git a/phaul/src/phaul/api.go b/phaul/src/phaul/api.go
> new file mode 100644
> index 0000000..6093a12
> --- /dev/null
> +++ b/phaul/src/phaul/api.go
> @@ -0,0 +1,52 @@
> +package phaul
> +
> +import (
> + "criu"
> +)
> +
> +/*
> + * Configuration passed around
> + *
> + * Pid is what we migrate
> + * Memfd is the file descriptor via which criu can
> + * transfer memory pages.
> + * Wdir is the directory where phaul can put images
> + * and other stuff
> + */
> +type PhaulConfig struct {
> + Pid int
> + Memfd int
> + Wdir string
> +}
> +
> +/*
> + * Rpc between PhaulClient and PhaulServer. When client
> + * calls anything on this one, the corresponding method
> + * should be called on PhaulServer object.
> + */
> +type PhaulRemote interface {
> + StartIter() error
> + StopIter() error
> +}
> +
> +/*
> + * Interface to local classes. PhaulClient calls them when
> + * it needs something on the source node.
> + *
> + * Methods:
> + *
> + * - DumpCopyRestore() is called on client side when the
> + * pre-iterations are over and it's time to do full dump,
> + * copy images and restore them on the server side.
> + * All the time this method is executed victim tree is
> + * frozen on client. Returning nil kills the tree, error
> + * unfreezes it and resumes. The criu argument is the
> + * pointer on created criu.Criu object on which client
> + * may call Dump(). The requirement on opts passed are:
> + * set Ps.Fd to comm.Memfd
> + * set ParentImg to last_client_images_path
> + * set TrackMem to true
> + */
> +type PhaulLocal interface {
> + DumpCopyRestore(criu *criu.Criu, c PhaulConfig, last_client_images_path string) error
> +}
> diff --git a/phaul/src/phaul/client.go b/phaul/src/phaul/client.go
> new file mode 100644
> index 0000000..06fb821
> --- /dev/null
> +++ b/phaul/src/phaul/client.go
> @@ -0,0 +1,130 @@
> +package phaul
> +
> +import (
> + "criu"
> + "fmt"
> + "github.com/golang/protobuf/proto"
> + "rpc"
> + "stats"
> +)
> +
> +const minPagesWritten uint64 = 64
> +const maxIters int = 8
> +const maxGrowDelta int64 = 32
> +
> +type PhaulClient struct {
> + local PhaulLocal
> + remote PhaulRemote
> + cfg PhaulConfig
> +}
> +
> +/*
> + * Main entry point. Caller should create the client object by
> + * passing here local, remote and comm. See comment in corresponding
> + * interfaces/structs for explanation.
> + *
> + * Then call client.Migrate() and enjoy :)
> + */
> +func MakePhaulClient(l PhaulLocal, r PhaulRemote, c PhaulConfig) (*PhaulClient, error) {
> + return &PhaulClient{local: l, remote: r, cfg: c}, nil
> +}
> +
> +func isLastIter(iter int, stats *stats.DumpStatsEntry, prev_stats *stats.DumpStatsEntry) bool {
> + if iter >= maxIters {
> + fmt.Printf("`- max iters reached\n")
> + return true
> + }
> +
> + pagesWritten := stats.GetPagesWritten()
> + if pagesWritten < minPagesWritten {
> + fmt.Printf("`- tiny pre-dump (%d) reached\n", int(pagesWritten))
> + return true
> + }
> +
> + pages_delta := int64(pagesWritten) - int64(prev_stats.GetPagesWritten())
> + if pages_delta >= maxGrowDelta {
> + fmt.Printf("`- grow iter (%d) reached\n", int(pages_delta))
> + return true
> + }
> +
> + return false
> +}
> +
> +func (pc *PhaulClient) Migrate() error {
> + criu := criu.MakeCriu()
> + psi := rpc.CriuPageServerInfo{
> + Fd: proto.Int32(int32(pc.cfg.Memfd)),
> + }
> + opts := rpc.CriuOpts{
> + Pid: proto.Int32(int32(pc.cfg.Pid)),
> + LogLevel: proto.Int32(4),
> + LogFile: proto.String("pre-dump.log"),
> + Ps: &psi,
> + }
> +
> + err := criu.Prepare()
> + if err != nil {
> + return err
> + }
> +
> + defer criu.Cleanup()
> +
> + imgs, err := preparePhaulImages(pc.cfg.Wdir)
> + if err != nil {
> + return err
> + }
> + prev_stats := &stats.DumpStatsEntry{}
> + iter := 0
> +
> + for {
> + err = pc.remote.StartIter()
> + if err != nil {
> + return err
> + }
> +
> + prev_p := imgs.lastImagesDir()
> + img_dir, err := imgs.openNextDir()
> + if err != nil {
> + return err
> + }
> +
> + opts.ImagesDirFd = proto.Int32(int32(img_dir.Fd()))
> + if prev_p != "" {
> + opts.ParentImg = proto.String(prev_p)
> + }
> +
> + err = criu.PreDump(opts, nil)
> + img_dir.Close()
> + if err != nil {
> + return err
> + }
> +
> + err = pc.remote.StopIter()
> + if err != nil {
> + return err
> + }
> +
> + st, err := criuGetDumpStats(img_dir)
> + if err != nil {
> + return err
> + }
> +
> + if isLastIter(iter, st, prev_stats) {
> + break
> + }
> +
> + prev_stats = st
> + }
> +
> + err = pc.remote.StartIter()
> + if err == nil {
> + prev_p := imgs.lastImagesDir()
> + err = pc.local.DumpCopyRestore(criu, pc.cfg, prev_p)
> + err2 := pc.remote.StopIter()
> + if err == nil {
> + err = err2
> + }
> + }
> +
> + return err
> +}
> diff --git a/phaul/src/phaul/images.go b/phaul/src/phaul/images.go
> new file mode 100644
> index 0000000..5a433ca
> --- /dev/null
> +++ b/phaul/src/phaul/images.go
> @@ -0,0 +1,41 @@
> +package phaul
> +
> +import (
> + "fmt"
> + "os"
> + "path/filepath"
> +)
> +
> +type images struct {
> + cursor int
> + dir string
> +}
> +
> +func preparePhaulImages(wdir string) (*images, error) {
> + return &images{dir: wdir}, nil
> +}
> +
> +func (i *images) getPath(idx int) string {
> + return fmt.Sprintf(i.dir+"/%d", idx)
> +}
> +
> +func (i *images) openNextDir() (*os.File, error) {
> + ipath := i.getPath(i.cursor)
> + err := os.Mkdir(ipath, 0700)
> + if err != nil {
> + return nil, err
> + }
> +
> + i.cursor++
> + return os.Open(ipath)
> +}
> +
> +func (i *images) lastImagesDir() string {
> + var ret string
> + if i.cursor == 0 {
> + ret = ""
> + } else {
> + ret, _ = filepath.Abs(i.getPath(i.cursor - 1))
> + }
> + return ret
> +}
> diff --git a/phaul/src/phaul/server.go b/phaul/src/phaul/server.go
> new file mode 100644
> index 0000000..8992ee9
> --- /dev/null
> +++ b/phaul/src/phaul/server.go
> @@ -0,0 +1,73 @@
> +package phaul
> +
> +import (
> + "criu"
> + "fmt"
> + "github.com/golang/protobuf/proto"
> + "rpc"
> +)
> +
> +type PhaulServer struct {
> + cfg PhaulConfig
> + imgs *images
> + cr *criu.Criu
> +}
> +
> +/*
> + * Main entry point. Make the server with comm and call PhaulRemote
> + * methods on it upon client requests.
> + */
> +func MakePhaulServer(c PhaulConfig) (*PhaulServer, error) {
> + img, err := preparePhaulImages(c.Wdir)
> + if err != nil {
> + return nil, err
> + }
> +
> + cr := criu.MakeCriu()
> +
> + return &PhaulServer{imgs: img, cfg: c, cr: cr}, nil
> +}
> +
> +/*
> + * PhaulRemote methods
> + */
> +func (s *PhaulServer) StartIter() error {
> + fmt.Printf("S: start iter\n")
> + psi := rpc.CriuPageServerInfo{
> + Fd: proto.Int32(int32(s.cfg.Memfd)),
> + }
> + opts := rpc.CriuOpts{
> + LogLevel: proto.Int32(4),
> + LogFile: proto.String("ps.log"),
> + Ps: &psi,
> + }
> +
> + prev_p := s.imgs.lastImagesDir()
> + img_dir, err := s.imgs.openNextDir()
> + if err != nil {
> + return err
> + }
> + defer img_dir.Close()
> +
> + opts.ImagesDirFd = proto.Int32(int32(img_dir.Fd()))
> + if prev_p != "" {
> + opts.ParentImg = proto.String(prev_p)
> + }
> +
> + return s.cr.StartPageServer(opts)
> +}
> +
> +func (s *PhaulServer) StopIter() error {
> + return nil
> +}
> +
> +/*
> + * Server-local methods
> + */
> +func (s *PhaulServer) LastImagesDir() string {
> + return s.imgs.lastImagesDir()
> +}
> +
> +func (s *PhaulServer) GetCriu() *criu.Criu {
> + return s.cr
> +}
> diff --git a/phaul/src/phaul/stats.go b/phaul/src/phaul/stats.go
> new file mode 100644
> index 0000000..77eb346
> --- /dev/null
> +++ b/phaul/src/phaul/stats.go
> @@ -0,0 +1,31 @@
> +package phaul
> +
> +import (
> + "github.com/golang/protobuf/proto"
> + "os"
> + "stats"
> +)
> +
> +/* FIXME: report stats from CriuResp */
> +func criuGetDumpStats(img_dir *os.File) (*stats.DumpStatsEntry, error) {
> + stf, err := os.Open(img_dir.Name() + "/stats-dump")
> + if err != nil {
> + return nil, err
> + }
> + defer stf.Close()
> +
> + buf := make([]byte, 2*4096)
> + sz, err := stf.Read(buf)
> + if err != nil {
> + return nil, err
> + }
> +
> + st := &stats.StatsEntry{}
> + // Skip 2 magic values and entry size
> + err = proto.Unmarshal(buf[12:sz], st)
> + if err != nil {
> + return nil, err
> + }
> +
> + return st.GetDump(), nil
> +}
> diff --git a/phaul/src/test/main.go b/phaul/src/test/main.go
> new file mode 100644
> index 0000000..0e853df
> --- /dev/null
> +++ b/phaul/src/test/main.go
> @@ -0,0 +1,188 @@
> +package main
> +
> +import (
> + "criu"
> + "fmt"
> + "github.com/golang/protobuf/proto"
> + "os"
> + "phaul"
> + "rpc"
> + "strconv"
> + "strings"
> + "syscall"
> +)
> +
> +type testLocal struct {
> + criu.CriuNoNotify
> + r *testRemote
> +}
> +
> +type testRemote struct {
> + srv *phaul.PhaulServer
> +}
> +
> +/* Dir where test will put dump images */
> +const images_dir = "test_images"
> +
> +func prepareImages() error {
> + err := os.Mkdir(images_dir, 0700)
> + if err != nil {
> + return err
> + }
> +
> + /* Work dir for PhaulClient */
> + err = os.Mkdir(images_dir+"/local", 0700)
> + if err != nil {
> + return err
> + }
> +
> + /* Work dir for PhaulServer */
> + err = os.Mkdir(images_dir+"/remote", 0700)
> + if err != nil {
> + return err
> + }
> +
> + /* Work dir for DumpCopyRestore */
> + err = os.Mkdir(images_dir+"/test", 0700)
> + if err != nil {
> + return err
> + }
> +
> + return nil
> +}
> +
> +func mergeImages(dump_dir, last_pre_dump_dir string) error {
> + idir, err := os.Open(dump_dir)
> + if err != nil {
> + return err
> + }
> +
> + defer idir.Close()
> +
> + imgs, err := idir.Readdirnames(0)
> + if err != nil {
> + return err
> + }
> +
> + for _, fname := range imgs {
> + if !strings.HasSuffix(fname, ".img") {
> + continue
> + }
> +
> + fmt.Printf("\t%s -> %s/\n", fname, last_pre_dump_dir)
> + err = syscall.Link(dump_dir+"/"+fname, last_pre_dump_dir+"/"+fname)
> + if err != nil {
> + return err
> + }
> + }
> +
> + return nil
> +}
> +
> +func (r *testRemote) doRestore() error {
> + last_srv_images_dir := r.srv.LastImagesDir()
> + /*
> + * In images_dir we have images from dump, in the
> + * last_srv_images_dir -- where server-side images
> + * (from page server, with pages and pagemaps) are.
> + * Need to put former into latter and restore from
> + * them.
> + */
> + err := mergeImages(images_dir+"/test", last_srv_images_dir)
> + if err != nil {
> + return err
> + }
> +
> + img_dir, err := os.Open(last_srv_images_dir)
> + if err != nil {
> + return err
> + }
> + defer img_dir.Close()
> +
> + opts := rpc.CriuOpts{
> + LogLevel: proto.Int32(4),
> + LogFile: proto.String("restore.log"),
> + ImagesDirFd: proto.Int32(int32(img_dir.Fd())),
> + }
> +
> + cr := r.srv.GetCriu()
> + fmt.Printf("Do restore\n")
> + return cr.Restore(opts, nil)
> +}
> +
> +func (l *testLocal) PostDump() error {
> + return l.r.doRestore()
> +}
> +
> +func (l *testLocal) DumpCopyRestore(cr *criu.Criu, cfg phaul.PhaulConfig, last_cln_images_dir string) error {
> + fmt.Printf("Final stage\n")
> +
> + img_dir, err := os.Open(images_dir + "/test")
> + if err != nil {
> + return err
> + }
> + defer img_dir.Close()
> +
> + psi := rpc.CriuPageServerInfo{
> + Fd: proto.Int32(int32(cfg.Memfd)),
> + }
> +
> + opts := rpc.CriuOpts{
> + Pid: proto.Int32(int32(cfg.Pid)),
> + LogLevel: proto.Int32(4),
> + LogFile: proto.String("dump.log"),
> + ImagesDirFd: proto.Int32(int32(img_dir.Fd())),
> + TrackMem: proto.Bool(true),
> + ParentImg: proto.String(last_cln_images_dir),
> + Ps: &psi,
> + }
> +
> + fmt.Printf("Do dump\n")
> + return cr.Dump(opts, l)
> +}
> +
> +func main() {
> + pid, _ := strconv.Atoi(os.Args[1])
> + fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
> + if err != nil {
> + fmt.Printf("Can't make socketpair\n")
> + return
> + }
> +
> + err = prepareImages()
> + if err != nil {
> + fmt.Printf("Can't prepare dirs for images\n")
> + return
> + }
> +
> + fmt.Printf("Make server part (socket %d)\n", fds[1])
> + srv, err := phaul.MakePhaulServer(phaul.PhaulConfig{
> + Pid: pid,
> + Memfd: fds[1],
> + Wdir: images_dir + "/remote"})
> + if err != nil {
> + return
> + }
> +
> + r := &testRemote{srv}
> +
> + fmt.Printf("Make client part (socket %d)\n", fds[0])
> + cln, err := phaul.MakePhaulClient(&testLocal{r: r}, srv,
> + phaul.PhaulConfig{
> + Pid: pid,
> + Memfd: fds[0],
> + Wdir: images_dir + "/local"})
> + if err != nil {
> + return
> + }
> +
> + fmt.Printf("Migrate\n")
> + err = cln.Migrate()
> + if err != nil {
> + fmt.Printf("Failed: ")
> + fmt.Print(err)
> + return
> + }
> +
> + fmt.Printf("SUCCESS!\n")
> +}
> --
> 2.5.0
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