mirror of
https://github.com/checkpoint-restore/criu.git
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7b0fa86d66
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@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
57 lines
888 B
C
57 lines
888 B
C
#define _GNU_SOURCE
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#include <stdio.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include <sched.h>
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#define STKS (4*4096)
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#ifndef CLONE_NEWPID
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#define CLONE_NEWPID 0x20000000
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#endif
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static int do_test(void *logf)
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{
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int fd, i = 0;
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setsid();
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close(0);
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close(1);
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close(2);
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fd = open("/dev/null", O_RDONLY);
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if (fd != 0) {
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dup2(fd, 0);
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close(fd);
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}
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fd = open(logf, O_WRONLY | O_TRUNC | O_CREAT, 0600);
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dup2(fd, 1);
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dup2(fd, 2);
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if (fd != 1 && fd != 2)
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close(fd);
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while (1) {
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sleep(1);
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printf("%d\n", i++);
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fflush(stdout);
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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int pid;
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void *stk;
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stk = mmap(NULL, STKS, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANON | MAP_GROWSDOWN, 0, 0);
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pid = clone(do_test, stk + STKS, SIGCHLD | CLONE_NEWPID, argv[1]);
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printf("Child forked, pid %d\n", pid);
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return 0;
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}
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