snapcraft: go build -trimpath

[simondeziel]

https://go.dev/doc/go1.13#go-command:

The new go build flag -trimpath removes all file system paths
from the compiled executable, to improve build reproducibility.

Another benefit is the resulting snap is smaller:

# df -ha | grep -wF /snap/lxd
/dev/loop5      152M  152M     0 100% /snap/lxd/25899  # latest-edge
/dev/loop0      149M  149M     0 100% /snap/lxd/x2        # snap from this PR

Some of those ~3M saved are due to not including the path to go's snap nor the build directory:

# strings /snap/lxd/25899/bin/lx* | grep -E '^/(snap|build/lxd)/' | sort -R | tail
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/snap/go/10339/src/internal/poll/sendfile_linux.go
/build/lxd/parts/lxd-migrate/build/.go/pkg/mod/golang.org/x/[email protected]/internal/poly1305/sum_generic.go
/build/lxd/parts/lxd/src/lxd/db/cluster/snapshots.mapper.go
/build/lxd/parts/lxd/src/lxd/db/cluster/snapshots.mapper.go

# ll /snap/lxd/{25899,x2}/bin/lx{c,d} | sort
-rwxr-xr-x 1 root root 16111912 Oct  6 02:42 /snap/lxd/x2/bin/lxc*
-rwxr-xr-x 1 root root 16144880 Oct  5 13:58 /snap/lxd/25899/bin/lxc*
-rwxr-xr-x 1 root root 44666280 Oct  6 02:42 /snap/lxd/x2/bin/lxd*
-rwxr-xr-x 1 root root 44736112 Oct  5 13:58 /snap/lxd/25899/bin/lxd*

# strings /snap/lxd/25899/bin/lx* | grep -E '^/(snap|build/lxd)/' | wc -c
687812

# strings /snap/lxd/x2/bin/lx* | grep -E '^/(snap|build/lxd)/' | wc -c
0

[tomponline]

Can you do this on MicroCloud too please @simondeziel

Thanks

[simondeziel]

Can you do this on MicroCloud too please @simondeziel

canonical/microcloud-pkg-snap#2