build: add static linking support

[0xe3b0c4]

improve from PR #17247

This adds a new flag to the ci.go install script, -static which produces static linked binary.

Note: this is only working in Alpine Linux musl library

Results:

No dynamic library dependencies

[karalabe]

Static linking is always a can of worms. What's the gain?

[karalabe]

Static linking on ubuntu produces a lot of warnings:

$ go build -ldflags "-extldflags '-static'" ./cmd/geth
# github.com/ethereum/go-ethereum/cmd/geth
/usr/bin/ld: /tmp/go-link-1415708301/000014.o: in function `mygetgrouplist':
/_/os/user/getgrouplist_unix.go:15: warning: Using 'getgrouplist' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-1415708301/000013.o: in function `mygetgrgid_r':
/_/os/user/cgo_lookup_unix.go:37: warning: Using 'getgrgid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-1415708301/000013.o: in function `mygetgrnam_r':
/_/os/user/cgo_lookup_unix.go:42: warning: Using 'getgrnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-1415708301/000013.o: in function `mygetpwnam_r':
/_/os/user/cgo_lookup_unix.go:32: warning: Using 'getpwnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-1415708301/000013.o: in function `mygetpwuid_r':
/_/os/user/cgo_lookup_unix.go:27: warning: Using 'getpwuid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-1415708301/000010.o: in function `_cgo_6cc2654a8ed3_C2func_getaddrinfo':
/tmp/go-build/cgo-gcc-prolog:58: warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking

AFAIK, there have been many issues reported, problems with networking, different versions of libc. Saving a couple megabytes on a docker images is not worth the risks that this can of worms can introduce.

[0xe3b0c4]

@karalabe Static linking only use in alpine (or other musl library environment), I can use it (non docker environment, but copy geth from docker image) on any Linux distribution without having to download the golang to build from source

[fjl]

I think we can fix these warnings by also setting -tags osusergo.

[fjl]

Actually, it needs to be -tags netgo,osusergo. These build tags disable the use of cgo in packages "net" and "os/user".

[0xe3b0c4]

Wow that's great, I didn't know that approach.

[fjl]

I have tested this and it works now. Enabling static linking in our Docker builds has a key advantage: you can copy the executable into another container without worrying about the Linux distribution used by our build container. For example, you could build an image like this:

FROM ethereum/client-go:latest AS geth
FROM ubuntu:latest
COPY -from=geth /usr/local/bin/geth /geth