[OpenWrt-Devel] running docker on openwrt?

Torbjorn Jansson torbjorn.jansson at mbox200.swipnet.se
Sun Sep 30 13:04:42 EDT 2018

On 2018-09-30 17:18, Daniel Golle wrote:
> On Sun, Sep 30, 2018 at 04:52:04PM +0200, Torbjorn Jansson wrote:
>> On 2018-09-30 16:21, Daniel Golle wrote:
>>> On Sun, Sep 30, 2018 at 02:18:54PM +0200, Torbjorn Jansson wrote:
>>>> On 2018-09-30 13:59, Daniel Golle wrote:
>>>>> On Sun, Sep 30, 2018 at 12:21:12PM +0200, Torbjorn Jansson wrote:
>>>>>> Hello.
>>>>>> a question, is it possible to run docker on openwrt?
>>>>>> reason for asking is that i got a raspberrypi running openwrt and it got
>>>>>> plenty of storage space and is mostly sitting idle so if i can run docker on
>>>>>> it i might be able to consolidate some of the other pis i have for various
>>>>>> purposes.
>>>>>> i know you can do it the other way around, running openwrt in a docker
>>>>>> instance on a regular computer but can you get docker itself to run under
>>>>>> openwrt?
>>>>>> ideas, suggestions?
>>>>> Just use LXC, that works well on OpenWrt, I'm using that to run various
>>>>> containers running Debian and OpenWrt on top of OpenWrt.
>>>>> (but you need to compile it yourself because many of the kernel options
>>>>> needed for containers aren't enabled by default)
>>>>> Docker didn't attract a lot of interest because it is x86_64 and
>>>>> ARM-only, so 80% of OpenWrt-supported devices aren't supported by
>>>>> Docker which doesn't provide images for MIPS-like CPUs.
>>>>> However, now that Golang has been added to the packages feed we could
>>>>> package Docker at least for the platforms supported by it...
>>>> ok, i see.
>>>> i've never tried lxc and i think docker also needs some extra kernel config
>>>> options for it to work.
>>>> i ran the script from:
>>>> https://raw.githubusercontent.com/docker/docker/master/contrib/check-config.sh
>>>> on one of my boxes and it complained about:
>>>> - CONFIG_NAMESPACES: missing
>>>> - CONFIG_NET_NS: missing
>>>> - CONFIG_PID_NS: missing
>>>> - CONFIG_IPC_NS: missing
>>>> - CONFIG_UTS_NS: missing
>>>> - CONFIG_CGROUPS: missing
>>>> - CONFIG_CGROUP_DEVICE: missing
>>>> - CONFIG_CGROUP_SCHED: missing
>>>> - CONFIG_CPUSETS: missing
>>>> - CONFIG_MEMCG: missing
>>>> - CONFIG_POSIX_MQUEUE: missing
>>>> and then there were a bunch of optional features also missing.
>>> For now the binary distribution doesn't have all those kernel features
>>> enabled. You need to compile from source and make sure that
>>> CONFIG_LXC_KERNEL_OPTIONS is set, this selects all the kernel options
>>> needed to run containers.
>> i see, so a package can modify the kernel options and enable needed features.
>> that's quite handy, i didn't know that.
>> what i tried to do was to run:
>> make kernel_menuconfig CONFIG_TARGET=subtarget
>> and then pick the right options myself and then check it with:
>> git diff target/linux/
>> the diff looked good but the resulting image did not include my extra kernel
>> config options for some reason and in don't understand why.
> This is not the intended ue of make kernel_menuconfig, that's why...
>> i assumed the stuff in target/linux/brcm2708/bcm2710/config-4.9 was going to
>> be used as a default template or something but maybe other config options is
>> overriding it.
> Exactly. The kernel options which are also listed in OpenWrt's .config
> always override the target-specific selection made by kernel_menuconfig.
>> i'm no expert on the build system (yet?) so any pointers for manually adding
>> a few extra config options for testing purposes would be nice.
> Just use the regular menuconfig's options mentioned above, all the
> cgroups and namespace stuff is listed there as well.

ok, my idea was to add a few extra options too.
so i guess i'll have to figure out how to make a small package of my own that 
adds all the kernel options, like the lxc one you pointed to.

is it safe to assume that the build system will take care of dependencies in 
the kernel config? or do i have to figure that out myself and make sure i also 
add any kernel config dependencies?

> Luka Perkov (@lperkov )and Marko Ratkaj (@ratkaj) can supposedly tell
> you more about the LXC integration in OpenWrt.

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