From building and installing the example plugin the logical next step, to my mind, was to copy that plugin as a template and build and install my-plugin to the ModDwarf. To that end I copied the eg-amp directory: mod-plugin-builder/plugins/package/my-plugin and edited all files to change eg-amp to my-plugin.
This all went well, but too well. The OpenEmbedded build system appears to build my plugin:
mod-plugin-builder$ ./build moddwarf my-plugin
it’ll even install my plugin:
mod-plugin-builder$ ./build moddwarf my-plugin-publish
The funny thing is that when I do publish using the above command I get the output:
{“removed”: [], “ok”: true, “installed”: [“http://lv2plug.in/plugins/eg-amp”]}
All plugin bundles installed
That’s not right, it’s found eg-amp. I’d already changed the source file for the project from amp.c to my-plugin.c and put that into the make files instead of amp.c. So I put a syntax error in the file just to make sure the build process would fail. As if, build system took it in its stride. Obviously buildroot isn’t building what I think it should be building. I looked at the output directory:
/mod-plugin-builder$ ls ~/mod-workdir/moddwarf/plugins/my-plugin.lv2/
amp.so amp.ttl manifest.ttl
So yeah even though the plugin has my name it’s pulling in amp.c rather then my-plugin.c
There are no occurrences of ‘es-amp’ or amp.c left in my project directory, but somehow buildroot knows to ignore everything. I think the offending line must be at the top of the my-plugin.mk
//# where to find the source code - locally in this case
MY_PLUGIN_SITE_METHOD = local
MY_PLUGIN_SITE = $($(PKG)_PKGDIR)/
I assume that $PKG is coming from the command mod-plugin-builder$ ./build moddwarf my-plugin
Been a few days at this going through [1] and all I can say is it’s slow going, so a few more to go 
[1] The Buildroot user manual