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/templates.go

@@ -0,0 +1,195 @@
+/*
+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 (
+	"bufio"
+	"bytes"
+	"io"
+	"os"
+	"text/template"
+)
+
+var kustomizationTmpl = `---
+{{- $eventsAddr := .EventsAddr }}
+{{- $watchAllNamespaces := .WatchAllNamespaces }}
+{{- $registry := .Registry }}
+{{- $arch := .Arch }}
+{{- $logLevel := .LogLevel }}
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+namespace: {{.Namespace}}
+
+transformers:
+  - labels.yaml
+
+resources:
+  - namespace.yaml
+{{- if .NetworkPolicy }}
+  - policies.yaml
+{{- end }}
+  - roles
+{{- range .Components }}
+  - {{.}}.yaml
+{{- end }}
+
+patches:
+- path: node-selector.yaml
+  target:
+    kind: Deployment
+
+patchesJson6902:
+{{- range $i, $component := .Components }}
+{{- if eq $component "notification-controller" }}
+- target:
+    group: apps
+    version: v1
+    kind: Deployment
+    name: {{$component}}
+  patch: |-
+    - op: replace
+      path: /spec/template/spec/containers/0/args/0
+      value: --watch-all-namespaces={{$watchAllNamespaces}}
+    - op: replace
+      path: /spec/template/spec/containers/0/args/1
+      value: --log-level={{$logLevel}}
+{{- else }}
+- target:
+    group: apps
+    version: v1
+    kind: Deployment
+    name: {{$component}}
+  patch: |-
+    - op: replace
+      path: /spec/template/spec/containers/0/args/0
+      value: --events-addr={{$eventsAddr}}
+    - op: replace
+      path: /spec/template/spec/containers/0/args/1
+      value: --watch-all-namespaces={{$watchAllNamespaces}}
+    - op: replace
+      path: /spec/template/spec/containers/0/args/2
+      value: --log-level={{$logLevel}}
+{{- end }}
+{{- end }}
+
+{{- if $registry }}
+images:
+{{- range $i, $component := .Components }}
+  - name: fluxcd/{{$component}}
+{{- if eq $arch "amd64" }}
+    newName: {{$registry}}/{{$component}}
+{{- else }}
+    newName: {{$registry}}/{{$component}}-arm64
+{{- end }}
+{{- end }}
+{{- end }}
+`
+
+var kustomizationRolesTmpl = `---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - rbac.yaml
+nameSuffix: -{{.Namespace}}
+`
+
+var nodeSelectorTmpl = `---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: all
+spec:
+  template:
+    spec:
+      nodeSelector:
+        kubernetes.io/arch: {{.Arch}}
+        kubernetes.io/os: linux
+{{- if .ImagePullSecret }}
+      imagePullSecrets:
+       - name: {{.ImagePullSecret}}
+{{- end }}
+`
+
+var labelsTmpl = `---
+apiVersion: builtin
+kind: LabelTransformer
+metadata:
+  name: labels
+labels:
+  app.kubernetes.io/instance: {{.Namespace}}
+  app.kubernetes.io/version: "{{.Version}}"
+fieldSpecs:
+  - path: metadata/labels
+    create: true
+`
+
+var namespaceTmpl = `---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: {{.Namespace}}
+`
+
+func execTemplate(obj interface{}, tmpl, filename string) error {
+	t, err := template.New("tmpl").Parse(tmpl)
+	if err != nil {
+		return err
+	}
+
+	var data bytes.Buffer
+	writer := bufio.NewWriter(&data)
+	if err := t.Execute(writer, obj); err != nil {
+		return err
+	}
+
+	if err := writer.Flush(); err != nil {
+		return err
+	}
+
+	file, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	_, err = io.WriteString(file, data.String())
+	if err != nil {
+		return err
+	}
+
+	return file.Sync()
+}
+
+func copyFile(src, dst string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, in)
+	if err != nil {
+		return err
+	}
+	return out.Close()
+}