Update wireguard package?

Hmm…it should have worked. I ran into the same issue when I was building/testing the Dockerfile.
That’s what this line is meant to fix:

echo -e “SECTIONS {\n\t.core.plt : { BYTE(0) }\n\t.init.plt : { BYTE(0) }\n}” > $kernel_dir/module.lds

That line creates the module.lds file with the following contents:

SECTIONS {
.core.plt : { BYTE(0) }
.init.plt : { BYTE(0) }
}

I would try it again. In any case I’ve posted an updated version that should be easier to manage going forward. With this version the only thing you’d need to change in the future is the line:
ENV SDK OpenWrt-SDK-mvebu_gcc-4.8-linaro_musl-1.1.15_eabi.Linux-x86_64
It just needs to match the SDK filename at:
https://api.turris.cz/openwrt-repo/omnia/

Try building it again with Dockerfile I’ve just posted, and let me know if you’re successful.

BTW, I just built this image two minutes ago. It produced the following files:
kmod-wireguard_4.4.59+0.0.20170409-1-627f0117679bc72ef5e58881035f567a-4_mvebu.ipk
wireguard_0.0.20170409-1_mvebu.ipk
wireguard-tools_0.0.20170409-1_mvebu.ipk