With the help of userfaultfd CRIU supports lazy migration. Lazy
migration means that memory pages are only transferred from the
migration source to the migration destination on page fault.
This enables to reduce the downtime during process or container
migration to a minimum as the memory does not need to be transferred
during migration.
Lazy migration currently depends on userfaultfd being available on the
current Linux kernel and if the used CRIU version supports lazy
migration. Both dependencies can be checked by querying CRIU via RPC if
the lazy migration feature is available. Using feature checking instead
of version comparison enables runC to use CRIU features from the
criu-dev branch. This way the user can decide if lazy migration should
be available by choosing the right kernel and CRIU branch.
To use lazy migration the CRIU process during dump needs to dump
everything besides the memory pages and then it opens a network port
waiting for remote page fault requests:
# runc checkpoint httpd --lazy-pages --page-server 0.0.0.0:27 \
--status-fd /tmp/postcopy-pipe
In this example CRIU will hang/wait once it has opened the network port
and wait for network connection. As runC waits for CRIU to finish it
will also hang until the lazy migration has finished. To know when the
restore on the destination side can start the '--status-fd' parameter is
used:
#️ runc checkpoint --help | grep status
--status-fd value criu writes \0 to this FD once lazy-pages is ready
The parameter '--status-fd' is directly from CRIU and this way the
process outside of runC which controls the migration knows exactly when
to transfer the checkpoint (without memory pages) to the destination and
that the restore can be started.
On the destination side it is necessary to start CRIU in 'lazy-pages'
mode like this:
# criu lazy-pages --page-server --address 192.168.122.3 --port 27 \
-D checkpoint
and tell runC to do a lazy restore:
# runc restore -d --image-path checkpoint --work-path checkpoint \
--lazy-pages httpd
If both processes on the restore side have the same working directory
'criu lazy-pages' creates a unix domain socket where it waits for
requests from the actual restore. runC starts CRIU restore in lazy
restore mode and talks to 'criu lazy-pages' that it wants to restore
memory pages on demand. CRIU continues to restore the process and once
the process is running and accesses the first non-existing memory page
the 'criu lazy-pages' server will request the page from the source
system. Thus all pages from the source system will be transferred to the
destination system. Once all pages have been transferred runC on the
source system will end and the container will have finished migration.
This can also be combined with CRIU's pre-copy support. The combination
of pre-copy and post-copy (lazy migration) provides the possibility to
migrate containers with minimal downtimes.
Some additional background about post-copy migration can be found in
these articles:
https://lisas.de/~adrian/?p=1253https://lisas.de/~adrian/?p=1183
Signed-off-by: Adrian Reber <areber@redhat.com>
Before adding the actual lazy migration support, this adds the feature
check for lazy-pages. Right now lazy migration, which is based on
userfaultd is only available in the criu-dev branch and not yet in a
release. As the check does not dependent on a certain version but on
a CRIU feature which can be queried it can be part of runC without a new
version check depending on a feature from criu-dev.
Signed-off-by: Adrian Reber <areber@redhat.com>
It looks like we missed this in 5930d5b427 ("Remove shfmt"), which was
causing CI to break (since it looks like the repo has moved or something
like that). Since we're no longer using shfmt, drop it completely from
the repo.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Fixes a race that occurred very frequently in testing where the tty of
the container may be closed by the time that runc gets to sending
SIGWINCH. This failure mode is not fatal, but it would cause test
failures due to expected outputs not matching. On further review it
appears that the original addition of these checks in 4c5bf649d0
("Check error return values") was actually not necessary, so partially
revert that change.
The particular failure mode this resolves would manifest as error logs
of the form:
time="2017-08-24T07:59:50Z" level=error msg="bad file descriptor"
Fixes: 4c5bf649d0 ("Check error return values")
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Fixes: #1557
I'm not quite sure about the root cause, looks like
systemd still want them to be uint64.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
While we have significant protections in place against CVE-2016-9962, we
still were holding onto a file descriptor that referenced the host
filesystem. This meant that in certain scenarios it was still possible
for a semi-privileged container to gain access to the host filesystem
(if they had CAP_SYS_PTRACE).
Instead, open the FIFO itself using a O_PATH. This allows us to
reference the FIFO directly without providing the ability for
directory-level access. When opening the FIFO inside the init process,
open it through procfs to re-open the actual FIFO (this is currently the
only supported way to open such a file descriptor).
Signed-off-by: Aleksa Sarai <asarai@suse.de>
The documentation here:
https://docs.docker.com/engine/security/userns-remap/#user-namespace-known-limitations
says that readonly containers can't be used with user namespaces do to some
kernel restriction. In fact, there is a special case in the kernel to be
able to do stuff like this, so let's use it.
This takes us from:
ubuntu@docker:~$ docker run -it --read-only ubuntu
docker: Error response from daemon: oci runtime error: container_linux.go:262: starting container process caused "process_linux.go:339: container init caused \"rootfs_linux.go:125: remounting \\\"/dev\\\" as readonly caused \\\"operation not permitted\\\"\"".
to:
ubuntu@docker:~$ docker-runc --version
runc version 1.0.0-rc4+dev
commit: ae2948042b08ad3d6d13cd09f40a50ffff4fc688-dirty
spec: 1.0.0
ubuntu@docker:~$ docker run -it --read-only ubuntu
root@181e2acb909a:/# touch foo
touch: cannot touch 'foo': Read-only file system
Signed-off-by: Tycho Andersen <tycho@docker.com>
When doing incremental dumps is useful to use auto deduplication of
memory images to save space.
Signed-off-by: Nikolas Sepos <nikolas.sepos@gmail.com>
Both tty.resize and notifySocket.setupSocket return an error which isn't
handled in the caller. Fix this and either log or propagate the errors.
Found using https://github.com/mvdan/unparam
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
To make sure that `make release` doesn't suddenly break after we've cut
a release, smoke-test the release scripts. The script won't fail if GPG
keys aren't found, so running in CI shouldn't be a huge issue.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This script is far easier to use than the previous `make release`
target, not to mention that it also automatically signs all of the
artefacts and makes everything really easy to do for maintainers.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
congfig.Sysctl setting is duplicated.
when contianer is rootless and Linux is nil, runc will panic.
Signed-off-by: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
state.json should be a reflection of the container's
realtime state, including resource configurations,
so we should update state.json after updating container
resources.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Go has supported PIC builds for a while now, and given the security
benefits of using PIC binaries we should really enable them. There also
appears to be some indication that non-PIC builds have been interacting
oddly on ppc64le (the linker cannot load some shared libraries), and
using PIC builds appears to solve this problem.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Fixes: #1228
It can be reproduced by applying this patch:
```diff
@@ -45,6 +46,7 @@ func registerMemoryEvent(cgDir string, evName string, arg string) (<-chan struct
go func() {
defer func() {
close(ch)
+ <-time.After(1 * time.Second)
eventfd.Close()
evFile.Close()
}()
```
We can close channel after fds were closed.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
The "go build -i" invocation may slightly help with incremental
recompilation, but it will cause builds to fail if $GOROOT is not
writeable by the current user. While this does appear to work sometimes,
it's a concern for external build systems where "-i" causes build errors
for no real gain.
Given the size of the runc project, --install is not really giving us
much anyway.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Linux is not always not nil.
If Linux is nil, panic will occur.
Signed-off-by: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Before this change, some file type would be treated as char devices
(e.g. symlinks).
Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
This allows the libcontainer to automatically clean up runc:[1:CHILD]
processes created as part of nsenter.
Signed-off-by: Alex Fang <littlelightlittlefire@gmail.com>
Unfortunately I don't have enough time to be a maintainer of runc.
I am not going to disappear from the community and as before
I always ready to help with anything.
Signed-off-by: Andrei Vagin <avagin@openvz.org>
With this runC also uses RPC to ask CRIU for its version. CRIU supports
a VERSION RPC since CRIU 3.0 and using the RPC interface does not
require parsing the console output of CRIU (which could change anytime).
For older CRIU versions which do not yet have the VERSION RPC runC falls
back to its old CRIU output parsing mode.
Once CRIU 3.0 is the minimum version required for runC the old code can
be removed.
v2:
* adapt to changes in the previous patches based on the review
Signed-off-by: Adrian Reber <areber@redhat.com>
Update criurpc.proto for the upcoming VERSION RPC.
This includes lazy_pages for the upcoming lazy migration support.
Signed-off-by: Adrian Reber <areber@redhat.com>
To use the CRIU VERSION RPC the criuSwrk function is adapted to work
with CriuOpts set to 'nil' as CriuOpts is not required for the VERSION
RPC.
Also do not print c.criuVersion if it is '0' as the first RPC call will
always be the VERSION call and only after that the version will be
known.
Signed-off-by: Adrian Reber <areber@redhat.com>
Adrian Reber
Mrunal Patel
Michael Crosby
Aleksa Sarai
Qiang Huang
Tycho Andersen
Nikolas Sepos
Tobias Klauser
Ma Shimiao
Kenfe-Mickael Laventure
Alex Fang
Daniel, Dao Quang Minh
Andrei Vagin