Add set-gcp-location function.

Author: yuwenma

functions/go/gcp-set-location/Dockerfile

@@ -0,0 +1,15 @@
+FROM golang:1.17-alpine3.13
+ENV CGO_ENABLED=0
+WORKDIR /go/src/
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN go build -o /usr/local/bin/function ./
+
+#############################################
+
+FROM alpine:3.13
+COPY --from=0 /usr/local/bin/function /usr/local/bin/function
+ENTRYPOINT ["function"]

functions/go/gcp-set-location/fieldspec/region.go

@@ -0,0 +1,13 @@
+package fieldspec
+
+const (
+	RegionFieldSpecs = `
+region:
+- path: spec/location
+  group: storage.cnrm.cloud.google.com
+  version: v1beta1
+  kind: StorageBucket
+  create: true
+
+`
+)

functions/go/gcp-set-location/fieldspec/zone.go

@@ -0,0 +1,11 @@
+package fieldspec
+
+const (
+	ZoneFieldSpecs = `
+zone:
+- path: spec/location
+  apiVersion: yuwen.cnrm.cloud.google.com/v1beta1
+  kind: Yuwen
+  create: false
+`
+)

functions/go/gcp-set-location/go.mod

@@ -0,0 +1,33 @@
+module github.com/GoogleContainerTools/kpt-functions-catalog/functions/go/gcp-set-location
+
+go 1.17
+
+require (
+	sigs.k8s.io/kustomize/api v0.10.2-0.20211202184144-fe551be87b8d
+	sigs.k8s.io/kustomize/kyaml v0.13.1-0.20211202184144-fe551be87b8d
+)
+
+require (
+	github.com/PuerkitoBio/purell v1.1.1 // indirect
+	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-errors/errors v1.0.1 // indirect
+	github.com/go-openapi/jsonpointer v0.19.3 // indirect
+	github.com/go-openapi/jsonreference v0.19.3 // indirect
+	github.com/go-openapi/swag v0.19.5 // indirect
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/mailru/easyjson v0.7.0 // indirect
+	github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/spf13/cobra v1.2.1 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/stretchr/testify v1.7.0 // indirect
+	github.com/xlab/treeprint v0.0.0-20181112141820-a009c3971eca // indirect
+	golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4 // indirect
+	golang.org/x/text v0.3.5 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	k8s.io/kube-openapi v0.0.0-20210421082810-95288971da7e // indirect
+	sigs.k8s.io/yaml v1.2.0 // indirect
+)

functions/go/gcp-set-location/go.sum

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"sigs.k8s.io/kustomize/api/hasher"
+	"sigs.k8s.io/kustomize/api/resmap"
+	"sigs.k8s.io/kustomize/api/resource"
+	"sigs.k8s.io/kustomize/kyaml/fn/framework"
+	"sigs.k8s.io/kustomize/kyaml/fn/framework/command"
+)
+
+type Processor struct {}
+
+func newResMapFactory() *resmap.Factory {
+	resourceFactory := resource.NewFactory(&hasher.Hasher{})
+	resourceFactory.IncludeLocalConfigs = true
+	return resmap.NewFactory(resourceFactory)
+}
+
+func (p *Processor) Process(resourceList *framework.ResourceList) error {
+	err := func() error{
+		trans := &Transformer{}
+		err := trans.Config(resourceList.FunctionConfig)
+		if err != nil {
+			return err
+		}
+		resmapFactory := newResMapFactory()
+		resMap, err := resmapFactory.NewResMapFromRNodeSlice(resourceList.Items)
+		if err != nil {
+			return fmt.Errorf("failed to convert items to resource map: %w", err)
+		}
+		if err := trans.Transform(resMap); err != nil {
+			return err
+		}
+		resourceList.Items = resMap.ToRNodeSlice()
+		return nil
+	}()
+	if err != nil {
+		resourceList.Results = framework.Results{
+			&framework.Result{
+				Message:  err.Error(),
+				Severity: framework.Error,
+			},
+		}
+		return resourceList.Results
+	}
+	return nil
+}
+
+func main() {
+	cmd := command.Build(&Processor{}, command.StandaloneEnabled, false)
+	if err := cmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

functions/go/gcp-set-location/main.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/GoogleContainerTools/kpt-functions-catalog/functions/go/gcp-set-location/fieldspec"
+	"sigs.k8s.io/kustomize/api/filters/fsslice"
+	"sigs.k8s.io/kustomize/api/resmap"
+	"sigs.k8s.io/kustomize/api/types"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+const (
+	ZoneKey = "zone"
+	RegionKey = "region"
+)
+
+type Transformer struct {
+	zone string
+	region string
+	zoneFieldSpec types.FsSlice `json:"zone,omitempty" yaml:"zone,omitempty"`
+	regionFieldSpec types.FsSlice `json:"region,omitempty" yaml:"region,omitempty"`
+}
+
+func (t *Transformer) Config(fnConfigNode *yaml.RNode) error {
+	data := fnConfigNode.GetDataMap()
+	if data == nil {
+		return fmt.Errorf("missing `data` field in `ConfigMap` FunctionConfig")
+	}
+	zone, ok := data[ZoneKey]
+	if !ok {
+		return fmt.Errorf("missing `.data.%s` field in `ConfigMap` FunctionConfig", ZoneKey)
+	}
+	t.zone = zone
+	region, ok := data[RegionKey]
+	if !ok {
+		return fmt.Errorf("missing `.data.%s` field in `ConfigMap` FunctionConfig", RegionKey)
+	}
+	t.region = region
+
+	// Enumerate location field specs
+	var rfs RegionFieldSpecs
+	if err := yaml.Unmarshal([]byte(fieldspec.RegionFieldSpecs), &rfs); err != nil {
+		return err
+	}
+
+	t.regionFieldSpec = rfs.fieldSpecs
+	var zfs ZoneFieldSpecs
+	if err := yaml.Unmarshal([]byte(fieldspec.ZoneFieldSpecs), &zfs); err != nil {
+		return err
+	}
+	t.zoneFieldSpec = zfs.fieldSpecs
+	return nil
+}
+
+func (p *Transformer) Transform(m resmap.ResMap) error {
+	return m.ApplyFilter(LocaltionFieldSpecFilter{
+		Zone: p.zone,
+		Region: p.region,
+		ZFsSlice:  p.zoneFieldSpec,
+		RFsSlice:  p.regionFieldSpec,
+	})
+}
+
+type ZoneFieldSpecs struct {
+	fieldSpecs []types.FieldSpec `json:"zone,omitempty" yaml:"zone,omitempty"`
+
+}
+type RegionFieldSpecs struct {
+	fieldSpecs []types.FieldSpec `json:"region,omitempty" yaml:"region,omitempty"`
+}
+
+var _ kio.Filter = LocaltionFieldSpecFilter{}
+
+func (f LocaltionFieldSpecFilter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	_, err := kio.FilterAll(yaml.FilterFunc(f.filter)).Filter(nodes)
+	return nodes, err
+}
+
+type LocaltionFieldSpecFilter struct {
+	Zone string
+	Region string
+	ZFsSlice types.FsSlice `json:"zone,omitempty" yaml:"zone,omitempty"`
+	RFsSlice types.FsSlice `json:"region,omitempty" yaml:"region,omitempty"`
+}
+
+func (f LocaltionFieldSpecFilter) filter(node *yaml.RNode) (*yaml.RNode, error) {
+	zoneFilter := fsslice.Filter{
+		FsSlice:  f.ZFsSlice,
+		SetValue: f.updateZoneFn,
+	}
+	regionFilter := fsslice.Filter{
+		FsSlice:  f.RFsSlice,
+		SetValue: f.updateRegionFn,
+	}
+
+	if err := node.PipeE(zoneFilter, regionFilter); err != nil {
+		return nil, err
+	}
+	return node, nil
+}
+
+func (f LocaltionFieldSpecFilter) updateZoneFn(node *yaml.RNode) error {
+	return node.PipeE(updater{location: f.Zone})
+}
+
+func (f LocaltionFieldSpecFilter) updateRegionFn(node *yaml.RNode) error {
+	return node.PipeE(updater{location: f.Region})
+}
+
+type updater struct {
+	location string
+}
+
+func (u updater) Filter(rn *yaml.RNode) (*yaml.RNode, error) {
+	return rn.Pipe(yaml.FieldSetter{StringValue: u.location})
+}
+