Clarify whether a unique repository can be used both for Debian and Raspbian

[jcberthon]

File: engine/installation/linux/debian.md

Previous version of this document had clearer instruction on how to setup the Deb repository for Raspbian. In current release, Raspbian is still mentioned in the supported OS, but there is no longer a specific version for it.

Current document state:

$ sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/debian \
   $(lsb_release -cs) \
   stable"

It seems that for Raspbian we could possibly use:

$ sudo add-apt-repository \
   "deb [arch=armhf] https://download.docker.com/linux/debian \
   $(lsb_release -cs) \
   stable"

But that does not work. The add-apt-repository command does not work on Raspbian. What I did is the following:

$ echo "deb [arch=armhf] https://download.docker.com/linux/debian \
   $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list

That seems to work and I am able to install docker-ce but when doing sudo apt-get update I have the following warning:

W: Conflicting distribution: https://download.docker.com jessie InRelease (expected jessie but got )

Anyway, previous Docker release (e.g. 1.13.1) supported Debian and Raspbian for armhf (there was 2 distinct deb packages). The documentation is unclear now if a unique repository can be used for both Debian and Raspbian.

[sandor-juhasz]

I have ran into the same issue today. Another workaround until the page is fixed is to follow the quick install command from the Raspberry PI homepage's Docker article at https://www.raspberrypi.org/blog/docker-comes-to-raspberry-pi/ It will install the latest CE version.

[noncreature0714]

I'm working on this 💯 @mstanleyjones @londoncalling

[londoncalling]

Fixed by PR #2893

[jcberthon]

I cannot reopen this issue, but I'm going to propose a PR for this issue with slightly different changes which in my opinion are not perfect but getting closer what it should be.