/snap/bin not in $PATH on desktop

[Sylvain Pineau]

On 07/09/2016 16:20, Zygmunt Krynicki wrote:
>> On 7 Sep 2016, at 13:16, Sylvain Pineau <sylvain.pineau at canonical.com> wrote:
>>
>> Hello,
>>
>> I noticed that I was not able to call other snap commands from my own snap on my desktop.
>> So I tested what was defined using the hello-world.env command.
>>
>> On desktop (with ubuntu-core 16.04.1 rev 352)
>>
>> $ hello-world.env | grep ^PATH=
>> PATH=/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
>>
>> But on a true snappy system (with ubuntu-core 16.04.1 rev 453), I get:
>>
>> $ hello-world.env | grep ^PATH=
>> PATH=/home/ubuntu/bin:/home/ubuntu/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
>>
>> Is there any reason to not have /snap/bin as part of the $PATH available to snap commands?
> Snaps cannot execute other snaps. The PATH difference is caused by how snap-confine behaves when it runs on classic but in general even if you used an absolute path you would not be able to start any other applications from /snap/bin. Allowing this would create an implicit interface (dependency between your snap and some other, perhaps third party, snap).
>
> If you need access to executables that you control you can use the content interface to bind mount another snap into your own snap and execute those commands directly, with the same security profile as the running application.
>
> Best regards
> ZK
>
Let me add some context to my initial post.
Basically we need to test other snaps (commands) from our checkbox test 
runner (a different snap).
The issue I mentioned above was the ability to run docker commands from 
the checkbox snap.
Both were installed with --devmode.
But I'm not the owner of the docker snap so using the content interface 
won't work for us.
Let's consider we're just the owner of the checkbox snap.
We could add /snap/bin to our own wrappers but it seems to be a bad 
practice.

1. What other solutions could we use?
2. On non-classic environments, can we rely on $PATH having /snap/bin in 
the future?

Sylvain