Add graceful shutdown when interrupted

If implemented this permit restoring a clean state in case of signal
interruption.

Signed-off-by: Soule BA <soule@weave.works>

cmd/flux/build_kustomization.go

@@ -19,10 +19,11 @@ package main
 import (
 	"fmt"
 	"os"
+	"os/signal"
 
 	"github.com/spf13/cobra"
 
-	"github.com/fluxcd/flux2/internal/kustomization"
+	"github.com/fluxcd/flux2/internal/build"
 	kustomizev1 "github.com/fluxcd/kustomize-controller/api/v1beta2"
 )
 
@@ -33,7 +34,7 @@ var buildKsCmd = &cobra.Command{
 	Long: `The build command queries the Kubernetes API and fetches the specified Flux Kustomization. 
 It then uses the fetched in cluster flux kustomization to perform needed transformation on the local kustomization.yaml
 pointed at by --path. The local kustomization.yaml is generated if it does not exist. Finally it builds the overlays using the local kustomization.yaml, and write the resulting multi-doc YAML to stdout.`,
-	Example: `# Create a new overlay.
+	Example: `# Build the local manifests as they were built on the cluster
 flux build kustomization my-app --path ./path/to/local/manifests`,
 	ValidArgsFunction: resourceNamesCompletionFunc(kustomizev1.GroupVersion.WithKind(kustomizev1.KustomizationKind)),
 	RunE:              buildKsCmdRun,
@@ -64,18 +65,36 @@ func buildKsCmdRun(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("invalid resource path %q", buildKsArgs.path)
 	}
 
-	builder, err := kustomization.NewBuilder(kubeconfigArgs, name, buildKsArgs.path, kustomization.WithTimeout(rootArgs.timeout))
+	builder, err := build.NewBuilder(kubeconfigArgs, name, buildKsArgs.path, build.WithTimeout(rootArgs.timeout))
 	if err != nil {
 		return err
 	}
 
-	manifests, err := builder.Build()
-	if err != nil {
-		return err
+	// create a signal channel
+	sigc := make(chan os.Signal, 1)
+	signal.Notify(sigc, os.Interrupt)
+
+	errChan := make(chan error)
+	go func() {
+		manifests, err := builder.Build()
+		if err != nil {
+			errChan <- err
+		}
+
+		cmd.Print(string(manifests))
+		errChan <- nil
+	}()
+
+	select {
+	case <-sigc:
+		fmt.Println("Build cancelled... exiting.")
+		return builder.Cancel()
+	case err := <-errChan:
+		if err != nil {
+			return err
+		}
 	}
 
-	cmd.Print(string(manifests))
-
 	return nil
 
 }

cmd/flux/diff_kustomization.go

@@ -19,10 +19,11 @@ package main
 import (
 	"fmt"
 	"os"
+	"os/signal"
 
 	"github.com/spf13/cobra"
 
-	"github.com/fluxcd/flux2/internal/kustomization"
+	"github.com/fluxcd/flux2/internal/build"
 	kustomizev1 "github.com/fluxcd/kustomize-controller/api/v1beta2"
 )
 
@@ -31,7 +32,7 @@ var diffKsCmd = &cobra.Command{
 	Aliases: []string{"ks"},
 	Short:   "Diff Kustomization",
 	Long:    `The diff command does a build, then it performs a server-side dry-run and output the diff.`,
-	Example: `# Create a new overlay.
+	Example: `# Preview changes local changes as they were applied on the cluster
 flux diff kustomization my-app --path ./path/to/local/manifests`,
 	ValidArgsFunction: resourceNamesCompletionFunc(kustomizev1.GroupVersion.WithKind(kustomizev1.KustomizationKind)),
 	RunE:              diffKsCmdRun,
@@ -44,7 +45,7 @@ type diffKsFlags struct {
 var diffKsArgs diffKsFlags
 
 func init() {
-	diffKsCmd.Flags().StringVar(&diffKsArgs.path, "path", "", "Name of a file containing a file to add to the kustomization file.)")
+	diffKsCmd.Flags().StringVar(&diffKsArgs.path, "path", "", "Path to a local directory that matches the specified Kustomization.spec.path.)")
 	diffCmd.AddCommand(diffKsCmd)
 }
 
@@ -62,18 +63,36 @@ func diffKsCmdRun(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("invalid resource path %q", diffKsArgs.path)
 	}
 
-	builder, err := kustomization.NewBuilder(kubeconfigArgs, name, diffKsArgs.path, kustomization.WithTimeout(rootArgs.timeout))
+	builder, err := build.NewBuilder(kubeconfigArgs, name, diffKsArgs.path, build.WithTimeout(rootArgs.timeout))
 	if err != nil {
 		return err
 	}
 
-	output, err := builder.Diff()
-	if err != nil {
-		return err
+	// create a signal channel
+	sigc := make(chan os.Signal, 1)
+	signal.Notify(sigc, os.Interrupt)
+
+	errChan := make(chan error)
+	go func() {
+		output, err := builder.Diff()
+		if err != nil {
+			errChan <- err
+		}
+
+		cmd.Print(output)
+		errChan <- nil
+	}()
+
+	select {
+	case <-sigc:
+		fmt.Println("Build cancelled... exiting.")
+		return builder.Cancel()
+	case err := <-errChan:
+		if err != nil {
+			return err
+		}
 	}
 
-	cmd.Print(output)
-
 	return nil
 
 }

cmd/flux/diff_kustomization_test.go

@@ -25,7 +25,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/fluxcd/flux2/internal/kustomization"
+	"github.com/fluxcd/flux2/internal/build"
 	"github.com/fluxcd/pkg/ssa"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 )
@@ -85,7 +85,7 @@ func TestDiffKustomization(t *testing.T) {
 		"fluxns": allocateNamespace("flux-system"),
 	}
 
-	b, _ := kustomization.NewBuilder(kubeconfigArgs, "podinfo", "")
+	b, _ := build.NewBuilder(kubeconfigArgs, "podinfo", "")
 
 	resourceManager, err := b.Manager()
 	if err != nil {

go.mod

@@ -12,10 +12,10 @@ require (
 	github.com/fluxcd/image-reflector-controller/api v0.15.0
 	github.com/fluxcd/kustomize-controller/api v0.19.1
 	github.com/fluxcd/notification-controller/api v0.20.1
-	github.com/fluxcd/pkg/apis/kustomize v0.3.1
+	github.com/fluxcd/pkg/apis/kustomize v0.3.1 // indirect
 	github.com/fluxcd/pkg/apis/meta v0.10.2
 	github.com/fluxcd/pkg/runtime v0.12.3
-	github.com/fluxcd/pkg/ssa v0.10.0
+	github.com/fluxcd/pkg/ssa v0.11.0
 	github.com/fluxcd/pkg/ssh v0.3.1
 	github.com/fluxcd/pkg/untar v0.0.5
 	github.com/fluxcd/pkg/version v0.0.1
@@ -25,7 +25,7 @@ require (
 	github.com/gonvenience/ytbx v1.4.2
 	github.com/google/go-cmp v0.5.6
 	github.com/google/go-containerregistry v0.2.0
-	github.com/hashicorp/go-multierror v1.1.1
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-retryablehttp v0.7.0 // indirect
 	github.com/homeport/dyff v1.4.6
 	github.com/lucasb-eyer/go-colorful v1.2.0
@@ -49,7 +49,7 @@ require (
 )
 
 require (
-	github.com/drone/envsubst v1.0.3
+	github.com/fluxcd/pkg/kustomize v0.0.2
 	sigs.k8s.io/kustomize/kyaml v0.13.0
 )
 
@@ -72,6 +72,7 @@ require (
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/drone/envsubst/v2 v2.0.0-20210730161058-179042472c46 // indirect
 	github.com/emirpasic/gods v1.12.0 // indirect
 	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
 	github.com/exponent-io/jsonpath v0.0.0-20151013193312-d6023ce2651d // indirect

go.sum

@@ -194,8 +194,8 @@ github.com/docker/go-connections v0.4.0/go.mod h1:Gbd7IOopHjR8Iph03tsViu4nIes5Xh
 github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/docker/spdystream v0.0.0-20160310174837-449fdfce4d96/go.mod h1:Qh8CwZgvJUkLughtfhJv5dyTYa91l1fOUCrgjqmcifM=
 github.com/docopt/docopt-go v0.0.0-20180111231733-ee0de3bc6815/go.mod h1:WwZ+bS3ebgob9U8Nd0kOddGdZWjyMGR8Wziv+TBNwSE=
-github.com/drone/envsubst v1.0.3 h1:PCIBwNDYjs50AsLZPYdfhSATKaRg/FJmDc2D6+C2x8g=
-github.com/drone/envsubst v1.0.3/go.mod h1:N2jZmlMufstn1KEqvbHjw40h1KyTmnVzHcSc9bFiJ2g=
+github.com/drone/envsubst/v2 v2.0.0-20210730161058-179042472c46 h1:7QPwrLT79GlD5sizHf27aoY2RTvw62mO6x7mxkScNk0=
+github.com/drone/envsubst/v2 v2.0.0-20210730161058-179042472c46/go.mod h1:esf2rsHFNlZlxsqsZDojNBcnNs5REqIvRrWRHqX0vEU=
 github.com/dustin/go-humanize v0.0.0-20171111073723-bb3d318650d4/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/elazarl/goproxy v0.0.0-20180725130230-947c36da3153 h1:yUdfgN0XgIJw7foRItutHYUIhlcKzcSf5vDpdhQAKTc=
@@ -240,10 +240,12 @@ github.com/fluxcd/pkg/apis/kustomize v0.3.1 h1:wmb5D9e1+Rr3/5O3235ERuj+h2VKUArVf
 github.com/fluxcd/pkg/apis/kustomize v0.3.1/go.mod h1:k2HSRd68UwgNmOYBPOd6WbX6a2MH2X/Jeh7e3s3PFPc=
 github.com/fluxcd/pkg/apis/meta v0.10.2 h1:pnDBBEvfs4HaKiVAYgz+e/AQ8dLvcgmVfSeBroZ/KKI=
 github.com/fluxcd/pkg/apis/meta v0.10.2/go.mod h1:KQ2er9xa6koy7uoPMZjIjNudB5p4tXs+w0GO6fRcy7I=
+github.com/fluxcd/pkg/kustomize v0.0.2 h1:ipvQrxSeuGZDsPZrVUL6tYMlTR5xqYTZp6G0Tdy2hVs=
+github.com/fluxcd/pkg/kustomize v0.0.2/go.mod h1:AFwnf3OqQmpTCuwCARTGpPRMBf0ZFJNGCvW63KbgK04=
 github.com/fluxcd/pkg/runtime v0.12.3 h1:h21AZ3YG5MAP7DxFF9hfKrP+vFzys2L7CkUbPFjbP/0=
 github.com/fluxcd/pkg/runtime v0.12.3/go.mod h1:imJ2xYy/d4PbSinX2IefmZk+iS2c1P5fY0js8mCE4SM=
-github.com/fluxcd/pkg/ssa v0.10.0 h1:dhgWDeqz0/zAs5guzmPx/DMPCkzZdlEiPvCs1NChAQM=
-github.com/fluxcd/pkg/ssa v0.10.0/go.mod h1:S+qig7BTOxop0c134y8Yv8/iQST4Kt7S2xXiFkP4VMA=
+github.com/fluxcd/pkg/ssa v0.11.0 h1:ejEMlHPsbXMP8BJQx3+0PwoBgJur0mHiPcMNKcFwoOE=
+github.com/fluxcd/pkg/ssa v0.11.0/go.mod h1:S+qig7BTOxop0c134y8Yv8/iQST4Kt7S2xXiFkP4VMA=
 github.com/fluxcd/pkg/ssh v0.3.1 h1:iQw07bkX2rScactX8WYv+uMDsufFOlg8M3fV2TNs244=
 github.com/fluxcd/pkg/ssh v0.3.1/go.mod h1:Sebfv4Um51PvomuYdMvKRncQW5dtKhZ5J5TA+wiHNSQ=
 github.com/fluxcd/pkg/untar v0.0.5 h1:UGI3Ch1UIEIaqQvMicmImL1s9npQa64DJ/ozqHKB7gk=

internal/kustomization/build.go → internal/build/build.go

@@ -14,17 +14,19 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package kustomization
+package build
 
 import (
 	"bytes"
 	"context"
 	"encoding/base64"
 	"fmt"
+	"sync"
 	"time"
 
 	"github.com/fluxcd/flux2/internal/utils"
 	kustomizev1 "github.com/fluxcd/kustomize-controller/api/v1beta2"
+	"github.com/fluxcd/pkg/kustomize"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -37,9 +39,9 @@ import (
 )
 
 const (
-	controllerName         = "kustomize-controller"
-	controllerGroup        = "kustomize.toolkit.fluxcd.io"
-	mask            string = "**SOPS**"
+	controllerName  = "kustomize-controller"
+	controllerGroup = "kustomize.toolkit.fluxcd.io"
+	mask            = "**SOPS**"
 )
 
 var defaultTimeout = 80 * time.Second
@@ -53,6 +55,9 @@ type Builder struct {
 	name          string
 	namespace     string
 	resourcesPath string
+	// mu is used to synchronize access to the kustomization file
+	mu            sync.Mutex
+	action        kustomize.Action
 	kustomization *kustomizev1.Kustomization
 	timeout       time.Duration
 }
@@ -149,13 +154,15 @@ func (b *Builder) build() (m resmap.ResMap, err error) {
 	// generate kustomization.yaml if needed
 	action, er := b.generate(*k, b.resourcesPath)
 	if er != nil {
-		errf := CleanDirectory(b.resourcesPath, action)
+		errf := kustomize.CleanDirectory(b.resourcesPath, action)
 		err = fmt.Errorf("failed to generate kustomization.yaml: %w", fmt.Errorf("%v %v", er, errf))
 		return
 	}
 
+	b.action = action
+
 	defer func() {
-		errf := CleanDirectory(b.resourcesPath, action)
+		errf := b.Cancel()
 		if err == nil {
 			err = errf
 		}
@@ -185,18 +192,28 @@ func (b *Builder) build() (m resmap.ResMap, err error) {
 
 }
 
-func (b *Builder) generate(kustomization kustomizev1.Kustomization, dirPath string) (action, error) {
+func (b *Builder) generate(kustomization kustomizev1.Kustomization, dirPath string) (kustomize.Action, error) {
 	data, err := runtime.DefaultUnstructuredConverter.ToUnstructured(&kustomization)
 	if err != nil {
 		return "", err
 	}
-	gen := NewGenerator(unstructured.Unstructured{Object: data})
-	return gen.WriteFile(dirPath, WithSaveOriginalKustomization())
+	gen := kustomize.NewGenerator(unstructured.Unstructured{Object: data})
+
+	// acuire the lock
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	return gen.WriteFile(dirPath, kustomize.WithSaveOriginalKustomization())
 }
 
 func (b *Builder) do(ctx context.Context, kustomization kustomizev1.Kustomization, dirPath string) (resmap.ResMap, error) {
 	fs := filesys.MakeFsOnDisk()
-	m, err := BuildKustomization(fs, dirPath)
+
+	// acuire the lock
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	m, err := kustomize.BuildKustomization(fs, dirPath)
 	if err != nil {
 		return nil, fmt.Errorf("kustomize build failed: %w", err)
 	}
@@ -208,7 +225,7 @@ func (b *Builder) do(ctx context.Context, kustomization kustomizev1.Kustomizatio
 			if err != nil {
 				return nil, err
 			}
-			outRes, err := SubstituteVariables(ctx, b.client, unstructured.Unstructured{Object: data}, res)
+			outRes, err := kustomize.SubstituteVariables(ctx, b.client, unstructured.Unstructured{Object: data}, res)
 			if err != nil {
 				return nil, fmt.Errorf("var substitution failed for '%s': %w", res.GetName(), err)
 			}
@@ -263,3 +280,18 @@ func trimSopsData(res *resource.Resource) error {
 
 	return nil
 }
+
+// Cancel cancels the build
+// It restores a clean reprository
+func (b *Builder) Cancel() error {
+	// acuire the lock
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	err := kustomize.CleanDirectory(b.resourcesPath, b.action)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

internal/kustomization/build_test.go → internal/build/build_test.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package kustomization
+package build
 
 import (
 	"testing"