use explicit output

Dockerfile

@@ -1,4 +1,2 @@
 FROM busybox
-ADD built-check /opt/resource/check
-ADD built-in /opt/resource/in
-ADD built-out /opt/resource/out
+ADD assets/ /opt/resource/

build.yml

@@ -3,8 +3,11 @@ platform: linux
 image: docker:///concourse/static-golang
 
 inputs:
-  - name: time-resource
-    path: gopath/src/github.com/concourse/time-resource
+- name: time-resource
+  path: gopath/src/github.com/concourse/time-resource
+
+outputs:
+- name: built-resource
 
 run:
   path: gopath/src/github.com/concourse/time-resource/scripts/ci

scripts/build

@@ -1,5 +1,8 @@
 #!/bin/bash
 
-go build -o built-in in/main.go
-go build -o built-check check/main.go
-go build -o built-out out/main.go
+set -e -u -x
+
+mkdir -p assets
+go build -o assets/in in/main.go
+go build -o assets/check check/main.go
+go build -o assets/out out/main.go

scripts/ci

@@ -6,6 +6,8 @@ set -eu
 export GOPATH=$PWD/gopath
 export PATH=$GOPATH/bin:$PATH
 
+BUILD_DIR=$PWD/built-resource
+
 cd $GOPATH/src/github.com/concourse/time-resource
 
 export GOPATH=${PWD}/Godeps/_workspace:$GOPATH
@@ -16,3 +18,5 @@ go install github.com/onsi/ginkgo/ginkgo
 CGO_ENABLED=1 ginkgo -race -r -p "$@"
 
 ./scripts/build
+
+cp -a assets/ Dockerfile $BUILD_DIR