Unable to build

[ForceConstant]

Using 'docker run --rm -v "$PWD/promremotewrite":/promremotewrite -w /promremotewrite golang:1.12 go build' I get

go: finding github.com/prometheus/client_golang v0.9.4
go: finding github.com/prometheus/common v0.4.1
go: finding github.com/prometheus/client_golang v0.9.1
go: finding github.com/go-kit/kit v0.8.0
go: finding github.com/julienschmidt/httprouter v1.2.0
go: finding github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc
go: finding github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d
go: finding github.com/pkg/errors v0.8.0
go: finding golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5
go: finding golang.org/x/sync v0.0.0-20181108010431-42b317875d0f
go: finding gopkg.in/yaml.v2 v2.2.1
go: finding github.com/sirupsen/logrus v1.2.0
go: finding github.com/go-stack/stack v1.8.0
go: finding github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223
go: finding github.com/golang/protobuf v1.3.1
go: finding github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
go: finding github.com/matttproud/golang_protobuf_extensions v1.0.1
go: gopkg.in/yaml.v2@v2.2.1: unknown revision v2.2.1
go: finding github.com/gogo/protobuf v1.1.1
go: finding golang.org/x/net v0.0.0-20181114220301-adae6a3d119a
go: finding github.com/json-iterator/go v1.1.6
go: finding github.com/golang/protobuf v1.2.0
go: finding github.com/prometheus/procfs v0.0.2
go: finding github.com/modern-go/reflect2 v1.0.1
go: finding github.com/beorn7/perks v1.0.0
go: finding github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90
go: finding github.com/stretchr/testify v1.3.0
go: finding github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515
go: finding github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973
go: finding github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910
go: finding github.com/go-logfmt/logfmt v0.3.0
go: finding github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf
go: finding gopkg.in/alecthomas/kingpin.v2 v2.2.6
go: gopkg.in/alecthomas/kingpin.v2@v2.2.6: unknown revision v2.2.6
go: error loading module requirements