Migrate to Go modules

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

gateway/Dockerfile

@@ -1,8 +1,8 @@
 FROM --platform=${BUILDPLATFORM:-linux/amd64} teamserverless/license-check:0.3.9 as license-check
 
-FROM --platform=${BUILDPLATFORM:-linux/amd64} golang:1.13 as build
+FROM --platform=${BUILDPLATFORM:-linux/amd64} golang:1.15 as build
 
-ENV GO111MODULE=off
+ENV GO111MODULE=on
 ENV CGO_ENABLED=0
 
 ARG TARGETPLATFORM
@@ -19,6 +19,8 @@ COPY --from=license-check /license-check /usr/bin/
 WORKDIR /go/src/github.com/openfaas/faas/gateway
 
 COPY vendor         vendor
+COPY go.mod         go.mod
+COPY go.sum         go.sum
 
 COPY handlers       handlers
 COPY metrics        metrics
@@ -32,6 +34,8 @@ COPY version        version
 COPY scaling        scaling
 COPY pkg            pkg
 COPY main.go        .
+
+
 RUN license-check -path ./ --verbose=false "Alex Ellis" "OpenFaaS Authors" "OpenFaaS Author(s)"
 
 

gateway/go.mod

@@ -0,0 +1,18 @@
+module github.com/openfaas/faas/gateway
+
+go 1.15
+
+require (
+	github.com/docker/distribution v2.7.1+incompatible
+	github.com/gorilla/mux v1.8.0
+	github.com/nats-io/jwt v1.2.2 // indirect
+	github.com/nats-io/nats-streaming-server v0.20.0 // indirect
+	github.com/nats-io/stan.go v0.8.2 // indirect
+	github.com/openfaas/faas-provider v0.16.2
+	github.com/openfaas/nats-queue-worker v0.0.0-20200512211843-8e9eefd5a320
+	github.com/prometheus/client_golang v1.9.0
+	github.com/prometheus/client_model v0.2.0
+	github.com/prometheus/procfs v0.3.0 // indirect
+	go.uber.org/goleak v1.1.10
+	golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4 // indirect
+)