Always set -ldflags=-s for darwin

[grobie]

# darwin-amd64
rm -rf node_exporter node_exporter-0.12.0.darwin-amd64.tar.gz .build *-stamp
cd /go/src/github.com/prometheus/node_exporter && GO15VENDOREXPERIMENT=1 GOPATH=/go /usr/local/go/bin/go build -ldflags "-X main.Version=0.12.0 -X "github.com/prometheus/node_exporter"/collector.Version=0.12.0 -X "github.com/prometheus/node_exporter"/collector.Revision=dd76a68 -X "github.com/prometheus/node_exporter"/collector.Branch=master" -o node_exporter
# github.com/prometheus/node_exporter
/usr/local/go/pkg/tool/linux_amd64/link: /usr/local/go/pkg/tool/linux_amd64/link: combining dwarf failed: open /tmp/go-link-233789061/go.dwarf: no such file or directory

[sdurrheimer]

Is actually not a bug in promu. You will need to add the -s ldflag for cross-building node_exporter for darwin in order to get rid of the darwf error. It's the same for alertmanager.
golang/go#11994

[grobie]

It seems the ldflag -s is required. We should always inject it.

[grobie]

Yeah. I just learned that in https://groups.google.com/forum/#!msg/golang-nuts/tq5swmNInGI/DnLwtxzykv0J.