Break cyclical dependency of generated template fs

For `fluxctl install`, we embed a set of templates in the fluxctl
binary by generating a fake filesystem as Go code
(pkg/install/generated_templates.gogen.go).

But the code that generates the fake filesystem also _depends_ on the
fake filesystem, since it does double duty as a program for generating
example manifests from those templates.

This leads to a problem: if anything has upset the generation process,
it's not possible to regenerate the files, since the generation tool
won't build.

A related problem, worked around elsewhere (#2473), is that it's easy
to introduce spurious differences in the generated code -- which,
since it's checked in -- means painful merges.

In general we don't care about the generated Go code, only about what
it produces. This commit removes the generated file from the
"uncommitted change" detection (`make check-generated`); and uses
`fluxctl install` to generate the example files, removing the need for
the code generating program to depend on the code it's generating.

NB It's still necessary to commit the generated code, since other
projects depend on the install package.

Makefile

@@ -29,9 +29,11 @@ BUILD_DATE:=$(shell date -u +'%Y-%m-%dT%H:%M:%SZ')
 
 DOCS_PORT:=8000
 
+GENERATED_TEMPLATES_FILE=pkg/install/generated_templates.gogen.go
+
 all: $(GOBIN)/fluxctl $(GOBIN)/fluxd build/.flux.done
 
-release-bins:
+release-bins: $(GENERATED_TEMPLATES_FILE)
 	for arch in amd64; do \
 		for os in linux darwin windows; do \
 			CGO_ENABLED=0 GOOS=$$os GOARCH=$$arch go build -o "build/fluxctl_"$$os"_$$arch" $(LDFLAGS) -ldflags "-X main.version=$(shell ./docker/image-tag)" ./cmd/fluxctl/; \
@@ -51,7 +53,7 @@ clean:
 realclean: clean
 	rm -rf ./cache
 
-test: test/bin/helm test/bin/kubectl test/bin/kustomize
+test: test/bin/helm test/bin/kubectl test/bin/kustomize $(GENERATED_TEMPLATES_FILE)
 	PATH="${PWD}/bin:${PWD}/test/bin:${PATH}" go test ${TEST_FLAGS} $(shell go list ./... | grep -v "^github.com/fluxcd/flux/vendor" | sort -u)
 
 e2e: test/bin/helm test/bin/kubectl build/.flux.done
@@ -104,7 +106,7 @@ cache/%/helm-$(HELM_VERSION): docker/helm.version
 	tar -m -C ./cache -xzf cache/$*/helm-$(HELM_VERSION).tar.gz $*/helm
 	mv cache/$*/helm $@
 
-$(GOBIN)/fluxctl: $(FLUXCTL_DEPS)
+$(GOBIN)/fluxctl: $(FLUXCTL_DEPS) $(GENERATED_TEMPLATES_FILE)
 	go install ./cmd/fluxctl
 
 $(GOBIN)/fluxd: $(FLUXD_DEPS)
@@ -113,14 +115,19 @@ $(GOBIN)/fluxd: $(FLUXD_DEPS)
 integration-test: all
 	test/bin/test-flux
 
-generate-deploy: pkg/install/generated_templates.gogen.go
-	cd deploy && go run ../pkg/install/generate.go deploy
+generate-deploy: $(GOBIN)/fluxctl
+	$(GOBIN)/fluxctl install -o ./deploy \
+		--git-url git@github.com:fluxcd/flux-get-started \
+		--git-email flux@example.com \
+		--git-user 'Flux automation' \
+		--git-label flux-sync \
+		--namespace flux
 
-pkg/install/generated_templates.gogen.go: pkg/install/templates/*
-	cd pkg/install && go run generate.go embedded-templates
+$(GENERATED_TEMPLATES_FILE): pkg/install/templates/*.tmpl pkg/install/generate.go
+	go generate ./pkg/install
 
-check-generated: generate-deploy pkg/install/generated_templates.gogen.go
-	git diff --exit-code -- integrations/apis integrations/client pkg/install/generated_templates.gogen.go
+check-generated: generate-deploy
+	git diff --exit-code -- deploy/
 
 build-docs:
 	@cd docs && docker build -t flux-docs .

deploy/flux-deployment.yaml

@@ -145,6 +145,9 @@ spec:
         # Include this if you want to restrict the manifests considered by flux
         # to those under the following relative paths in the git repository
         # - --git-path=subdir1,subdir2
+        - --git-label=flux-sync
+        - --git-user=Flux automation
+        - --git-email=flux@example.com
 
         # Include these two to enable git commit signing
         # - --git-gpg-key-import=/root/gpg-import

pkg/install/generate.go

@@ -4,92 +4,28 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
-	"time"
 
 	"github.com/shurcooL/vfsgen"
-
-	"github.com/fluxcd/flux/pkg/install"
 )
 
 func main() {
 	usage := func() {
-		fmt.Fprintf(os.Stderr, "usage: %s {embedded-templates,deploy}\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "usage: %s\n", os.Args[0])
 		os.Exit(1)
 	}
-	if len(os.Args) != 2 {
+	if len(os.Args) != 1 {
 		usage()
 	}
-	switch os.Args[1] {
-	case "embedded-templates":
-		var fs http.FileSystem = modTimeFS{
-			fs: http.Dir("templates/"),
-		}
-		err := vfsgen.Generate(fs, vfsgen.Options{
-			Filename:     "generated_templates.gogen.go",
-			PackageName:  "install",
-			VariableName: "templates",
-		})
-		if err != nil {
-			log.Fatalln(err)
-		}
-	case "deploy":
-		params := install.TemplateParameters{
-			GitURL:    "git@github.com:fluxcd/flux-get-started",
-			GitBranch: "master",
-			Namespace: "flux",
-		}
-		manifests, err := install.FillInTemplates(params)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "error: failed to fill in templates: %s\n", err)
-			os.Exit(1)
-		}
-		for fileName, contents := range manifests {
-			if err := ioutil.WriteFile(fileName, contents, 0600); err != nil {
-				fmt.Fprintf(os.Stderr, "error: failed to write deploy file %s: %s\n", fileName, err)
-				os.Exit(1)
-			}
-		}
-
-	default:
-		usage()
-	}
-}
 
-// modTimeFS is a wrapper that rewrites all mod times to Unix epoch.
-// This is to ensure `generated_templates.gogen.go` only changes when
-// the folder and/or file contents change.
-type modTimeFS struct {
-	fs http.FileSystem
-}
-
-func (fs modTimeFS) Open(name string) (http.File, error) {
-	f, err := fs.fs.Open(name)
+	err := vfsgen.Generate(http.Dir("templates/"), vfsgen.Options{
+		Filename:     "generated_templates.gogen.go",
+		PackageName:  "install",
+		VariableName: "templates",
+	})
 	if err != nil {
-		return nil, err
+		log.Fatalln(err)
 	}
-	return modTimeFile{f}, nil
-}
-
-type modTimeFile struct {
-	http.File
-}
-
-func (f modTimeFile) Stat() (os.FileInfo, error) {
-	fi, err := f.File.Stat()
-	if err != nil {
-		return nil, err
-	}
-	return modTimeFileInfo{fi}, nil
-}
-
-type modTimeFileInfo struct {
-	os.FileInfo
-}
-
-func (modTimeFileInfo) ModTime() time.Time {
-	return time.Unix(0, 0)
 }