Update to return empty set for Namespaces call

The namespace call added to OpenFaaS was not implemented in
here, and that meant that calling it returned an empty response
rather than some valid json, A user noted that this caused an error
in the connector-sdk, which has had a fix added, but we need this
namespace endpoint to not return none (well it was actually erroring)

Signed-off-by: Alistair Hey <[email protected]>

handlers/namespace.go

@@ -0,0 +1,26 @@
+package handlers
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+)
+
+// Swarm does not use namespaces, so we return an empty list. see https://github.com/openfaas-incubator/connector-sdk/pull/46
+func NamespaceLister() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		namespaces := []string{}
+		nsJSON, err := json.Marshal(namespaces)
+
+		if err != nil {
+			log.Printf("Unable to marshal namespaces into JSON %q", err)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("\"error\": \"unable to return namespaces\""))
+		}
+
+		w.WriteHeader(http.StatusOK)
+		w.Write(nsJSON)
+	}
+}
+

main.go

@@ -64,6 +64,8 @@ func main() {
 		InfoHandler:    handlers.MakeInfoHandler(version.BuildVersion(), version.GitCommit),
 		SecretHandler:  handlers.MakeSecretsHandler(dockerClient),
 		LogHandler:     logs.NewLogHandlerFunc(handlers.NewLogRequester(dockerClient), cfg.FaaSConfig.WriteTimeout),
+		ListNamespaceHandler: handlers.NamespaceLister(),
+
 	}
 
 	bootstrapConfig := bootTypes.FaaSConfig{