Refactor manifests generation

- introduce manifestgen pkg, to be consumed by the CLI and Terraform provider
- consolidate defaults in manifestgen/install pkg
- introduce Manifest as the returning type of manifest generation
- add helper function to Manifest for writing multi-doc YAMLs on disk

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

pkg/manifestgen/install/options.go

@@ -0,0 +1,66 @@
+/*
+Copyright 2020 The Flux 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.
+*/
+
+package install
+
+import "time"
+
+type Options struct {
+	BaseURL                string
+	Version                string
+	Namespace              string
+	Components             []string
+	EventsAddr             string
+	Registry               string
+	ImagePullSecret        string
+	Arch                   string
+	WatchAllNamespaces     bool
+	NetworkPolicy          bool
+	LogLevel               string
+	NotificationController string
+	ManifestFile           string
+	Timeout                time.Duration
+	TargetPath             string
+}
+
+func MakeDefaultOptions() Options {
+	return Options{
+		Version:                "latest",
+		Namespace:              "gotk-system",
+		Components:             []string{"source-controller", "kustomize-controller", "helm-controller", "notification-controller"},
+		EventsAddr:             "",
+		Registry:               "ghcr.io/fluxcd",
+		ImagePullSecret:        "",
+		Arch:                   "amd64",
+		WatchAllNamespaces:     true,
+		NetworkPolicy:          true,
+		LogLevel:               "info",
+		BaseURL:                "https://github.com/fluxcd/toolkit/releases",
+		NotificationController: "notification-controller",
+		ManifestFile:           "gotk-components.yaml",
+		Timeout:                time.Minute,
+		TargetPath:             "",
+	}
+}
+
+func containsItemString(s []string, e string) bool {
+	for _, a := range s {
+		if a == e {
+			return true
+		}
+	}
+	return false
+}