add initial out command

cmd/out/out.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+
+	"github.com/concourse/github-release-resource"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		resource.Sayf("usage: %s <sources directory>\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	var request resource.OutRequest
+	inputRequest(&request)
+
+	sourceDir := os.Args[1]
+
+	github := resource.NewGitHubClient(request.Source)
+	command := resource.NewOutCommand(github)
+	response, err := command.Run(sourceDir, request)
+	if err != nil {
+		resource.Fatal("running command", err)
+	}
+
+	outputResponse(response)
+}
+
+func inputRequest(request *resource.OutRequest) {
+	if err := json.NewDecoder(os.Stdin).Decode(request); err != nil {
+		resource.Fatal("reading request from stdin", err)
+	}
+}
+
+func outputResponse(response resource.OutResponse) {
+	if err := json.NewEncoder(os.Stdout).Encode(response); err != nil {
+		resource.Fatal("writing response to stdout", err)
+	}
+}