Fix stack compose bind-mount volumes for Windows

[johnstep]

For stack compose files, use filepath.IsAbs instead of path.IsAbs, for
bind-mounted service volumes, because filepath.IsAbs handles Windows
paths, while path.IsAbs does not.

Signed-off-by: John Stephens johnstep@docker.com

[dnephin]

Thanks! LGTM

[cpuguy83]

Unfortunately doing this on the client side just does not work at all.

[dnephin]

@cpuguy83 I believe this works correctly on the client. absPath() is used in 4 places right now. 3 of the 4 I know are safe (env_file path, secret path, config path) because they always refer to paths handled by the client.

The last one (bind mount source path) is also a path relative to the client, so I think that's correct as well.

[cpuguy83]

The last one (bind mount source path) is also a path relative to the client, so I think that's correct as well.

This should never be a path relative to the client. Works great for compose as a relative path, does not really work on a swarm.

I'm also wondering how this affects docker4windows (windows client -> linux daemon).

[dnephin]

This should never be a path relative to the client.

What about when there is a single swarm node which is the localhost? Then local paths are just fine. We need to continue to support that workflow.

In every other case a client path will be wrong, so the user should use an absolute path.

[cpuguy83]

Sure we need to continue to support it but not in a cluster API.

…

On Tue, May 30, 2017 at 4:13 PM, Daniel Nephin ***@***.***> wrote: This should never be a path relative to the client. What about when there is a single swarm node which is the localhost? Then local paths are just fine. We need to continue to support that workflow. In every other case a client path will be wrong, so the user should use an absolute path. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#136 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAwxZhmFbbEXF82d-cxrHOwd07xUyb5Aks5r_HhjgaJpZM4Noctq> .

-- - Brian Goff

[dnephin]

To clarify. I meant we need to continue to support it for stack deploy. We should be able to use the same tool (stack deploy) to develop on a local cluster of 1, and a production cluster.

[johnstep]

This fix makes it possible to bind-mount volumes in stacks from the Windows client.

I verified this works with Windows Server 2016 containers, and with Docker for Windows with Linux containers. I tried to verify Windows containers as well, but am encountering an unrelated HNS error. Regardless, I can see that this corrects the problem by inspecting the service created for the stack.

However, this does not handle a Windows client creating a stack service from a Linux daemon, where the volume source path is a directory local to the daemon system. In the Docker for Windows case, that would be bind-mounting a volume from within the LinuxKit VM (normally the Windows path is translated automatically); the client working directory is irrelevant in that case. As @cpuguy83 suggested earlier (offline), it might be reasonable for the client to check for both Linux and Windows absolute paths.

[johnstep]

I updated this to do a Unix absolute path check first (via the previous check, path.IsAbs), and only perform the platform-specific check if that returns false. This has no effective impact on Linux/Unix clients, but should allow a Windows client to work with Linux/Unix and Windows daemons in all cases, while preserving support for relative paths for a single-nodes swarm.

[codecov-io]

Codecov Report

Merging #136 into master will decrease coverage by 0.1%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
- Coverage   44.96%   44.85%   -0.11%     
==========================================
  Files         169      169              
  Lines       11378    11379       +1     
==========================================
- Hits         5116     5104      -12     
- Misses       5970     5982      +12     
- Partials      292      293       +1

[dnephin]

LGTM

[mlaventure]

LGTM

[cpuguy83]

I think this works for now, but note that path really only applies to strings with / separators and not really unix paths specifically... however path.IsAbs and the unix implementation of filepath.IsAbs are essentially the same.

[johnstep]

@cpuguy83 Yes, true. A better solution might be to add a function that specifically checks for an absolute path on any platform, if that can be done in a reasonable way.

On a side note, the code that handles ~ is not going to work on Windows since the HOME environment variable is not generally set, but it's probably not something users expect on Windows anyway (though PowerShell supports it), and is just a minor convenience.