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,
@@ -64,17 +65,35 @@ 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)
 
-	cmd.Print(string(manifests))
+	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
+		}
+	}
 
 	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)
 }
 
@@ -62,17 +63,35 @@ 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)
 
-	cmd.Print(output)
+	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
+		}
+	}
 
 	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 {

cmd/flux/testdata/build-kustomization/delete-service/deployment.yaml

@@ -71,4 +71,4 @@ spec:
             memory: 512Mi
           requests:
             cpu: 100m
-            memory: 64Mi
+            memory: 64Mi

cmd/flux/testdata/build-kustomization/delete-service/hpa.yaml

@@ -17,4 +17,4 @@ spec:
         type: Utilization
         # scale up if usage is above
         # 99% of the requested CPU (100m)
-        averageUtilization: 99
+        averageUtilization: 99

cmd/flux/testdata/build-kustomization/podinfo-kustomization.yaml

@@ -12,4 +12,4 @@ spec:
   sourceRef:
     kind: GitRepository
     name: podinfo
-  targetNamespace: default
+  targetNamespace: default

cmd/flux/testdata/build-kustomization/podinfo-source.yaml

@@ -13,4 +13,4 @@ spec:
   interval: 30s
   ref:
     branch: master
-  url: https://github.com/stefanprodan/podinfo
+  url: https://github.com/stefanprodan/podinfo

cmd/flux/testdata/build-kustomization/podinfo/deployment.yaml

@@ -71,4 +71,4 @@ spec:
             memory: 512Mi
           requests:
             cpu: 100m
-            memory: 64Mi
+            memory: 64Mi

cmd/flux/testdata/build-kustomization/podinfo/hpa.yaml

@@ -17,4 +17,4 @@ spec:
         type: Utilization
         # scale up if usage is above
         # 99% of the requested CPU (100m)
-        averageUtilization: 99
+        averageUtilization: 99

cmd/flux/testdata/build-kustomization/podinfo/service.yaml

@@ -14,4 +14,4 @@ spec:
     - port: 9999
       targetPort: grpc
       protocol: TCP
-      name: grpc
+      name: grpc

cmd/flux/testdata/diff-kustomization/deployment.yaml

@@ -75,4 +75,4 @@ spec:
             memory: 512Mi
           requests:
             cpu: 100m
-            memory: 64Mi
+            memory: 64Mi

cmd/flux/testdata/diff-kustomization/kustomization.yaml

@@ -8,4 +8,4 @@ secretGenerator:
  - literals:
    - username=admin
    - password=1f2d1e2e67df
-   name: secret-basic-auth
+   name: secret-basic-auth

cmd/flux/testdata/diff-kustomization/secret.yaml

@@ -9,4 +9,4 @@ metadata:
       kustomize.toolkit.fluxcd.io/namespace: {{ .fluxns }}
   name: db-user-pass-bkbd782d2c
   namespace: default
-type: Opaque
+type: Opaque

cmd/flux/testdata/diff-kustomization/service.yaml

@@ -18,4 +18,4 @@ spec:
     - port: 9999
       targetPort: grpc
       protocol: TCP
-      name: grpc
+      name: grpc

cmd/flux/testdata/diff-kustomization/value-sops-secret.yaml

@@ -8,4 +8,4 @@ metadata:
       kustomize.toolkit.fluxcd.io/namespace: {{ .fluxns }}
   name: podinfo-token-77t89m9b67
   namespace: default
-type: Opaque
+type: Opaque