Replace glide with Go modules (#544)

* And attempt to build with modules and remove glide
* new tools.go file to get code-generator dependency + updated codegen + remove Glide files and update docs

hack/tools.go

@@ -0,0 +1,19 @@
+// +build tools
+
+/*
+Copyright 2019 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// This package imports things required by build scripts, to force `go mod` to see them as dependencies
+package tools
+
+import _ "k8s.io/code-generator"

hack/update-codegen.sh

@@ -7,7 +7,7 @@ set -o pipefail
 SCRIPT_ROOT=$(dirname ${BASH_SOURCE})/..
 CODEGEN_PKG=${CODEGEN_PKG:-$(cd ${SCRIPT_ROOT}; ls -d -1 ./vendor/k8s.io/code-generator 2>/dev/null || echo ${GOPATH}/src/k8s.io/code-generator)}
 
-vendor/k8s.io/code-generator/generate-groups.sh all \
+bash "${CODEGEN_PKG}/generate-groups.sh" all \
   github.com/zalando/postgres-operator/pkg/generated github.com/zalando/postgres-operator/pkg/apis \
-  acid.zalan.do:v1 \
-  --go-header-file ${SCRIPT_ROOT}/hack/custom-boilerplate.go.txt
+  "acid.zalan.do:v1" \
+  --go-header-file "${SCRIPT_ROOT}"/hack/custom-boilerplate.go.txt