Hi @refiktuzakli ,

DOCKER_GITCOMMIT provides information about the sources at runtime. See:
https://github.com/resin-os/balena/blob/b54f148fe1334735c1dc046643133c4708c501b0/hack/make.sh#L74
https://github.com/resin-os/balena/blob/df5d0f6fe7410472a0f8a4e1f45f991cf71d4def/hack/make/.go-autogen#L16
https://github.com/resin-os/balena/blob/df5d0f6fe7410472a0f8a4e1f45f991cf71d4def/dockerversion/useragent.go#L22

DOCKER_BUILDTAGS is used to strip the binary of things that were not tested/used. Basically, we deactivate the inclusion of some storage drivers.

I'm not sure what your question is about directory as .gopath/src/github.com/docker/docker.

We copy/install the mobynit tool too. https://github.com/resin-os/meta-resin/blob/master/meta-resin-common/recipes-containers/balena/balena_git.bb#L115 This tool is meant to be used when the root partition is a docker storage itself. So you can have a root file system as a docker image and use mobynit to mount that image and start an init system from it (for example systemd).

I mean we create a link with .gopath/src/github.com/docker/docker, why this path related with docker why not .gopath/src/github.com/resin-os/balena because we download this from github/resion-os/balena!

Another question is that What if we build without "-ldflags '-extldflags "-static"'", which functionality do we loos? size of balena binary remain same but size of mobynit binary goes down about 1M. How can we use mobynit binary when it build without ldflags?

thanks

1. linking to .gopath/src/github.com/docker/docker is done since internally the code refers to all subpackages with the github.com/docker/docker prefix, not doing so would break the build

2. those flags tell the Go compiler to build a static executable (which is actually trickier than just that: cmd/go: build: add -static flag golang/go#26492)

The Go package infra was updated to use Go modules and now the .gopath tree is no longer necessary / created.