CROSS COMPILE ALL THE THINGS

.dockerignore

@@ -0,0 +1 @@
+.gitignore

.gitignore

@@ -1 +1 @@
-gosu
+gosu*

Dockerfile

@@ -1,17 +1,22 @@
-FROM golang
+FROM golang:cross
 
 RUN mkdir -p /go/src/github.com/docker \
-	&& git clone https://github.com/docker/libcontainer.git /go/src/github.com/docker/libcontainer
+	&& git clone https://github.com/docker/libcontainer.git /go/src/github.com/docker/libcontainer \
+	&& cd /go/src/github.com/docker/libcontainer \
+	&& git checkout --quiet 4ae31b6ceb2c2557c9f05f42da61b0b808faa5a4
+
 ENV GOPATH $GOPATH:/go/src/github.com/docker/libcontainer/vendor
-# TODO pin specific commit
 
-# cache-fill
-RUN go get -d -v github.com/docker/libcontainer/namespaces
+ENV GOSU_ARCHES amd64 386 arm
 
-COPY . /go/src/github.com/tianon/gosu
+# disable CGO for ALL THE THINGS (to help ensure no libc)
+ENV CGO_ENABLED 0
+
+COPY *.go /go/src/github.com/tianon/gosu/
 WORKDIR /go/src/github.com/tianon/gosu
 
-RUN go get -d -v ./...
-RUN go build -v
-
-CMD [ "cat", "gosu" ]
+RUN GOARCH=amd64       go build -v -ldflags -d -o /go/bin/gosu-amd64
+RUN GOARCH=386         go build -v -ldflags -d -o /go/bin/gosu-386
+RUN GOARCH=arm GOARM=5 go build -v -ldflags -d -o /go/bin/gosu-armv5
+RUN GOARCH=arm GOARM=6 go build -v -ldflags -d -o /go/bin/gosu-armv6
+RUN GOARCH=arm GOARM=7 go build -v -ldflags -d -o /go/bin/gosu-armv7

build.sh

@@ -5,6 +5,7 @@ cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 
 set -x
 docker build -t gosu .
-docker run --rm gosu > gosu
-chmod +x gosu
-./gosu
+rm -f gosu*
+docker run --rm gosu bash -c 'cd /go/bin && tar -c gosu*' | tar -xv
+ls -lFh gosu*
+./gosu-amd64