runc fails to spawn the container due to /sys write

[rajasec]

Hi

I've created the OCP spec from the command
runc spec > container.json

runc encounters following error

Here is the error
WARN[0000] signal: killed
Timestamp: 2015-06-24 07:18:33.31193264 +0530 IST
Code: System error

Message: write /sys/fs/cgroup/memory/user/1000.user/4.session/sdc/memory.swappiness: invalid argument

My image is Ubuntu container from docker repository.

Here is the entire error log
runc
WARN[0000] signal: killed
Timestamp: 2015-06-24 07:18:33.31193264 +0530 IST
Code: System error

Message: write /sys/fs/cgroup/memory/user/1000.user/4.session/raj/memory.swappiness: invalid argument

Frames:

0: start
Package: github.com/opencontainers/runc/libcontainer.(*initProcess)

File: process_linux.go@197

1: Start
Package: github.com/opencontainers/runc/libcontainer.(*linuxContainer)

File: container_linux.go@107

2: execContainer
Package: main

File: run.go@41

3: func·006
Package: main

File: main.go@88

4: Run
Package: github.com/codegangsta/cli.(*App)

File: app.go@159

5: main
Package: main

File: main.go@96

6: main
Package: runtime

File: proc.go@63

7: goexit
Package: runtime
File: asm_amd64.s@2232

[LK4D4]

@rajasec Yeah, this is know issue. There was PR in libcontainer repo for fix, it will be migrated soon. @estesp was author IIRC

[rajasec]

Thanks Alexander Morozov.
I'll wait for the fix to happen..
Is anything related to cgroups not able to modify the /sys params ?

[estesp]

@rajasec this is related to an older cgroup limitation that didn't allow certain parameters (such as memory.swappiness) to be written in cgroup hierarchies if you aren't in the parent/root cgroup. This is no longer a restriction in current kernels, but if you are running 14.04LTS, for example, you hit this issue.

More information is available here: https://github.com/docker/libcontainer/issues/639#issue-89392076

[rajasec]

@estesp

Even I tried with the latest changes part of libcontainer in Docker project still failed
I've ensured that following file changes which got merged and available in my repository.

cgroups/fs/memory.go
cgroups/systemd/apply_systemd.go
configs/cgroup.go

Error thrown:
[8] System error: write /sys/fs/cgroup/memory/docker/ac23ecfc90b503e1d5c73b699bc3fef8ca99eadd07452d850de73fa4b029d688/memory.swappiness: invalid argument
make: *** [all] Error 1

I've created bug in libcontainer project.
"memory.swapiness fails to get updated in Docker 1.8_dev build #648"

[estesp]

@rajasec the Docker PR which fixes the same problem has not been merged yet--the change you would need for running Docker (which it appears you are from your log above) is in moby/moby#14030 which has not been merged yet (and changes the default template in the native execdriver in Docker)

[rajasec]

Thanks estesp.
I could successfully launch the container using runc today. I tried with basic ubuntu image and with container.json having the rootfs of ubuntu image. I could launch the container with the simple bash shell running inside the container
My kernel version : 3.13 ( based on 14.04 LTS).
Looks interesting to work

As I mentioned in another bug created, vendor directory is not available, neither update.sh will be available for vendor specific things.
I have manually pulled the changes inside libcontainer for compilation.

Very light weight without docker daemon

Thanks
Rajasec

[crosbymichael]

Fixed by #20