CC @crosbymichael @cpuguy83 @LK4D4 @mrunalp @rhatdan

If I specify two volumes one as shared and one as private

+   if hasSharedVolume {
+       execdriver.SetRootPropagation(container, mount.SHARED)
+       return nil
+   }
+
+   if hasSlaveVolume {
+       execdriver.SetRootPropagation(container, mount.RSLAVE)
+       return nil
+   }

Won't propogation end up being RSLAVE?

I first check if there are any shared volumes and set propagation to "shared" and return. I think you missed the "return" statement.

Simpler would be to just check if a higher level is set and then don't change it.

if root prop = shared don't set to private, or slave,
If root prop == slave don't set to private

@rhatdan I had thought about it. I think it is a good idea to implement it. Will do.

• Took care of Dan's comments. Now modifying root propagation only if needed.
• Updated documentation of man pages.
• Exported Propagation status through docker-inspect Mounts.

HOW TO TEST

• Make sure that source mount of directory being bind mounted is shared (for shared volumes) or shared/slave (for slave volumes).
• Bind mount a directory as shared volume.
  docker run -ti /root/mnt-source:/root/mnt-dest:shared --cap-add SYS_ADMIN fedora bash
• Inside container make sure mount is shared.
  findmnt -o TARGET,PROPAGATION /root/mnt-dest
• Do a mount under shared volume inside container
  mkdir -p /root/mnt-dest/mnt1
cd /root/mnt-dest
mount --bind mnt1 mnt1
• Make sure this new mount propagates to host. Run following on host.
  findmnt /root/mnt-source/mnt1

HOW TO DETERMINE SOURCE MOUNT

• Run df <directory> and it will tell what's the source mount. Looks for column Mounted on

HOW TO CHECK PROPAGATION PROPERTY OF A MOUNT
findmnt -o TARGET,PROPAGATION <mount-point>

HOW TO CHANGE PROPAGATION PROPERTY OF A MOUNT
mount --make-shared <mnt-point>
mount --make-slave <mnt-point>

@crosbymichael Fixed the array issue. Also I have added another patch which verifies that source mount point has appropriate propagation properties for volume mount to work, otherwise container start will fail. PTAL.

Looks like your additional change broke some stuff and there was a bad rebase

@crosbymichael Found the bug I had introduced. PropagationFlags need to be nil if there is no propagation flag to be applied. With the second round of changes, it got initialized to 0 and libcontainer was trying to apply that and failing. Fixed it.

Also rebased on top of latest code. This volume support on windows moved quite a few things around.

Build error on windows binaries

hmm..., Need to define volume.GetPropagation() for windows. Will do.

Defined a function GetPropagation() for windows which returns nil string. Hopefully that fixes windows build. lets see.

Apart from the godoc nit, LGTM from a Windows perspective. @rhvgoyal Apologies for the rebase pain with the introduction of volume support on Windows.

Took care of validate-lint issue. Added a comment starting with GetPropagation.

@crosbymichael Did some more changes. PTAL.

• Added some unit and integration tests.
• Reorganized the code a bit. Propagation logic is specific to linux and not all unix. So moved it to volume/volume_propagation_linux.go. And made windows, freebsd and darwin use definition from volume/volume_propagation_unsupported.go.

@crosbymichael Right now these are 3 patches. Do let me know if you want me to merge all this in single patch.

My newly introduced integration test TestRunVolumesMountedAsShared is failing. It passes on my local machine (make test-integration-cli). so this has something to do with environment. I am not sure what though. Anybody has a clue what might be going on or what else can I try.

FAIL: docker_cli_run_test.go:3615: DockerSuite.TestRunVolumesMountedAsShared

docker_cli_run_test.go:3644:
c.Fatalf("Failed to bind mount /volume-dest/mnt1: exit code %d", code)
... Error: Failed to bind mount /volume-dest/mnt1: exit code 255

Oh look, this is exactly what I need for a thing I'm doing at this moment. When can a release including this functionality be expected to appear?

@griwes this will be in the 1.10 release, probably in February. If you want to give it a test, you can either try the builds from master (https://master.dockerproject.org) or the experimental builds https://experimental.docker.com.

Is it assumed knowledge that /root/mnt-source in your example needs to be mounted as "shared" on the host before this will work?

$ sudo mount --bind /root/mnt-source /root/mnt-source
$ sudo mount --make-shared /root/mnt-source

Without this I got an error indicating that /root/mnt-source wasn't shared (under Ubuntu 14.04 with the latest experimental docker).

Yes this is expected. Note that RHEL7, Fedora, And Centos come this way by default.

@lox @rhatdan

How to set following permanently? I have to re mount it after reboot ubuntu...

sudo mount --bind /root/mnt-source /root/mnt-source
sudo mount --make-shared /root/mnt-source

Thx

Make a unit file or service script to do this.

@kiwenlau on 14.10+ with systemd you can set the MountFlags=shared and you wont need to set --make-shared each time. You can also set that in /etc/fstab with 14.10+.

on 14.04 you are limited to some type of init script for this (can also be a udev trigger depending on if that makes the situation better)

@rhatdan @SamYaple I use Ubuntu 14.04.
I can set mount in /etc/fstab:
/root/mnt-sourc         /root/mnt-sourc             none    bind            0       0

However, I can not set shared mount for it in fstab file. I have to manually set it when I reboot ubuntu
sudo mount --make-shared /root/mnt-source

It's OK for me, and I will try some init script to do it. Thanks.

@kiwenlau Yes i believe I stated that this only works on 14.10+ when set in /etc/fstab or with the mount binary.

If you pullin the mount binary from 14.10+ it would work, but may break other things