topology_plan.go

/*
Copyright 2022 The Kubernetes 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 cmd

import (
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"sort"
	"strings"

	"github.com/olekukonko/tablewriter"
	"github.com/pkg/errors"
	"github.com/spf13/cobra"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/utils/exec"
	crclient "sigs.k8s.io/controller-runtime/pkg/client"

	"sigs.k8s.io/cluster-api/cmd/clusterctl/client"
	"sigs.k8s.io/cluster-api/cmd/clusterctl/client/cluster"
	utilyaml "sigs.k8s.io/cluster-api/util/yaml"
)

type topologyPlanOptions struct {
	kubeconfig        string
	kubeconfigContext string
	files             []string
	cluster           string
	namespace         string
	outDir            string
}

var tp = &topologyPlanOptions{}

var topologyPlanCmd = &cobra.Command{
	Use:   "plan",
	Short: "List the changes to clusters that use managed topologies for a given input",
	Long: LongDesc(`
		Provide the list of objects that would be created, modified and deleted when an input file is applied.
		The input can be a file with a new/modified cluster, new/modified ClusterClass, new/modified templates.
		Details about the objects that will be created and modified will be stored in a path passed using --output-directory.

		This command can also be run without a real cluster. In such cases, the input should contain all the objects needed.

		Note: Among all the objects in the input defaulting and validation will be performed only for Cluster
		and ClusterClasses. All other objects in the input are expected to be valid and have default values.
	`),
	Example: Examples(`
		# List all the objects that will be created and modified when creating a new cluster.
		clusterctl alpha topology plan -f new-cluster.yaml -o output/
	    
		# List the changes when modifying a cluster.
		clusterctl alpha topology plan -f modified-cluster.yaml -o output/

		# List all the objects that will be created and modified when creating a new cluster along with a new ClusterClass.
		clusterctl alpha topology plan -f new-cluster-and-cluster-class.yaml -o output/

		# List the clusters impacted by a ClusterClass change.
		clusterctl alpha topology plan -f modified-cluster-class.yaml -o output/
	
		# List the changes to "cluster1" when a ClusterClass is changed.
		clusterctl alpha topology plan -f modified-cluster-class.yaml --cluster "cluster1" -o output/

		# List the clusters and ClusterClasses impacted by a template change.
		clusterctl alpha topology plan -f modified-template.yaml -o output/
	`),
	Args: cobra.NoArgs,
	RunE: func(cmd *cobra.Command, args []string) error {
		return runTopologyPlan()
	},
}

func init() {
	topologyPlanCmd.Flags().StringVar(&initOpts.kubeconfig, "kubeconfig", "",
		"Path to the kubeconfig for the management cluster. If unspecified, default discovery rules apply.")
	topologyPlanCmd.Flags().StringVar(&initOpts.kubeconfigContext, "kubeconfig-context", "",
		"Context to be used within the kubeconfig file. If empty, current context will be used.")

	topologyPlanCmd.Flags().StringArrayVarP(&tp.files, "file", "f", nil, "path to the file with new or modified resources to be applied; the file should not contain more than one Cluster or more than one ClusterClass")
	topologyPlanCmd.Flags().StringVarP(&tp.cluster, "cluster", "c", "", "name of the target cluster; this parameter is required when more than one cluster is affected")
	topologyPlanCmd.Flags().StringVarP(&tp.namespace, "namespace", "n", "", "target namespace for the operation. If specified, it is used as default namespace for objects with missing namespace")
	topologyPlanCmd.Flags().StringVarP(&tp.outDir, "output-directory", "o", "", "output directory to write details about created/modified objects")

	if err := topologyPlanCmd.MarkFlagRequired("file"); err != nil {
		panic(err)
	}
	if err := topologyPlanCmd.MarkFlagRequired("output-directory"); err != nil {
		panic(err)
	}

	topologyCmd.AddCommand(topologyPlanCmd)
}

func runTopologyPlan() error {
	c, err := client.New(cfgFile)
	if err != nil {
		return err
	}

	objs := []unstructured.Unstructured{}
	for _, f := range tp.files {
		raw, err := os.ReadFile(f) //nolint:gosec
		if err != nil {
			return errors.Wrapf(err, "failed to read input file %q", f)
		}
		objects, err := utilyaml.ToUnstructured(raw)
		if err != nil {
			return errors.Wrapf(err, "failed to convert file %q to list of objects", f)
		}
		objs = append(objs, objects...)
	}

	out, err := c.TopologyPlan(client.TopologyPlanOptions{
		Kubeconfig: client.Kubeconfig{Path: tp.kubeconfig, Context: tp.kubeconfigContext},
		Objs:       convertToPtrSlice(objs),
		Cluster:    tp.cluster,
		Namespace:  tp.namespace,
	})
	if err != nil {
		return err
	}
	return printTopologyPlanOutput(out, tp.outDir)
}

func printTopologyPlanOutput(out *cluster.TopologyPlanOutput, outdir string) error {
	printAffectedClusterClasses(out)
	printAffectedClusters(out)
	if len(out.Clusters) == 0 {
		// No affected clusters. Return early.
		return nil
	}
	if out.ReconciledCluster == nil {
		fmt.Printf("No target cluster identified. Use --cluster to specify a target cluster to get detailed changes.")
	} else {
		printChangeSummary(out)
		if err := writeOutputFiles(out, outdir); err != nil {
			return errors.Wrap(err, "failed to write output files of target cluster changes")
		}
	}
	fmt.Printf("\n")
	return nil
}

func printAffectedClusterClasses(out *cluster.TopologyPlanOutput) {
	if len(out.ClusterClasses) == 0 {
		// If there are no affected ClusterClasses return early. Nothing more to do here.
		fmt.Printf("No ClusterClasses will be affected by the changes.\n")
		return
	}
	fmt.Printf("The following ClusterClasses will be affected by the changes:\n")
	for _, cc := range out.ClusterClasses {
		fmt.Printf(" ＊ %s/%s\n", cc.Namespace, cc.Name)
	}
	fmt.Printf("\n")
}

func printAffectedClusters(out *cluster.TopologyPlanOutput) {
	if len(out.Clusters) == 0 {
		// if there are not affected Clusters return early. Nothing more to do here.
		fmt.Printf("No Clusters will be affected by the changes.\n")
		return
	}
	fmt.Printf("The following Clusters will be affected by the changes:\n")
	for _, cluster := range out.Clusters {
		fmt.Printf(" ＊ %s/%s\n", cluster.Namespace, cluster.Name)
	}
	fmt.Printf("\n")
}

func printChangeSummary(out *cluster.TopologyPlanOutput) {
	if len(out.Created) == 0 && len(out.Modified) == 0 && len(out.Deleted) == 0 {
		fmt.Printf("No changes detected for Cluster %q.\n", fmt.Sprintf("%s/%s", out.ReconciledCluster.Namespace, out.ReconciledCluster.Name))
		return
	}

	fmt.Printf("Changes for Cluster %q: \n", fmt.Sprintf("%s/%s", out.ReconciledCluster.Namespace, out.ReconciledCluster.Name))
	table := tablewriter.NewWriter(os.Stdout)
	table.SetHeader([]string{"Namespace", "Kind", "Name", "Action"})
	table.SetHeaderAlignment(tablewriter.ALIGN_LEFT)
	table.SetCenterSeparator("")
	table.SetColumnSeparator("")
	table.SetRowSeparator("")
	table.SetHeaderLine(false)
	table.SetBorder(false)

	// Add the created rows.
	sort.Slice(out.Created, func(i, j int) bool { return lessByKindAndName(out.Created[i], out.Created[j]) })
	for _, c := range out.Created {
		addRow(table, c, "created", tablewriter.FgGreenColor)
	}

	// Add the modified rows.
	sort.Slice(out.Modified, func(i, j int) bool { return lessByKindAndName(out.Modified[i].After, out.Modified[j].After) })
	for _, m := range out.Modified {
		addRow(table, m.After, "modified", tablewriter.FgYellowColor)
	}

	// Add the deleted rows.
	sort.Slice(out.Deleted, func(i, j int) bool { return lessByKindAndName(out.Deleted[i], out.Deleted[j]) })
	for _, d := range out.Deleted {
		addRow(table, d, "deleted", tablewriter.FgRedColor)
	}
	fmt.Printf("\n")
	table.Render()
	fmt.Printf("\n")
}

func writeOutputFiles(out *cluster.TopologyPlanOutput, outDir string) error {
	if _, err := os.Stat(outDir); os.IsNotExist(err) {
		return fmt.Errorf("output directory %q does not exist", outDir)
	}

	// Write created files
	createdDir := path.Join(outDir, "created")
	if err := os.MkdirAll(createdDir, 0750); err != nil {
		return errors.Wrapf(err, "failed to create %q directory", createdDir)
	}
	for _, c := range out.Created {
		yaml, err := utilyaml.FromUnstructured([]unstructured.Unstructured{*c})
		if err != nil {
			return errors.Wrap(err, "failed to convert object to yaml")
		}
		fileName := fmt.Sprintf("%s_%s_%s.yaml", c.GetKind(), c.GetNamespace(), c.GetName())
		filePath := path.Join(createdDir, fileName)
		if err := os.WriteFile(filePath, yaml, 0600); err != nil {
			return errors.Wrapf(err, "failed to write yaml to file %q", filePath)
		}
	}
	if len(out.Created) != 0 {
		fmt.Printf("Created objects are written to directory %q\n", createdDir)
	}

	// Write modified files
	modifiedDir := path.Join(outDir, "modified")
	if err := os.MkdirAll(modifiedDir, 0750); err != nil {
		return errors.Wrapf(err, "failed to create %q directory", modifiedDir)
	}
	for _, m := range out.Modified {
		// Write the modified object to file.
		fileNameModified := fmt.Sprintf("%s_%s_%s.modified.yaml", m.After.GetKind(), m.After.GetNamespace(), m.After.GetName())
		filePathModified := path.Join(modifiedDir, fileNameModified)
		if err := writeObjectToFile(filePathModified, m.After); err != nil {
			return errors.Wrap(err, "failed to write modified object to file")
		}

		// Write the original object to file.
		fileNameOriginal := fmt.Sprintf("%s_%s_%s.original.yaml", m.Before.GetKind(), m.Before.GetNamespace(), m.Before.GetName())
		filePathOriginal := path.Join(modifiedDir, fileNameOriginal)
		if err := writeObjectToFile(filePathOriginal, m.Before); err != nil {
			return errors.Wrap(err, "failed to write original object to file")
		}

		// Calculate the jsonpatch and write to a file.
		patch := crclient.MergeFrom(m.Before)
		jsonPatch, err := patch.Data(m.After)
		if err != nil {
			return errors.Wrapf(err, "failed to calculate jsonpatch of modified object %s/%s", m.After.GetNamespace(), m.After.GetName())
		}
		patchFileName := fmt.Sprintf("%s_%s_%s.jsonpatch", m.After.GetKind(), m.After.GetNamespace(), m.After.GetName())
		patchFilePath := path.Join(modifiedDir, patchFileName)
		if err := os.WriteFile(patchFilePath, jsonPatch, 0600); err != nil {
			return errors.Wrapf(err, "failed to write jsonpatch to file %q", patchFilePath)
		}

		// Calculate the diff and write to a file.
		diffFileName := fmt.Sprintf("%s_%s_%s.diff", m.After.GetKind(), m.After.GetNamespace(), m.After.GetName())
		diffFilePath := path.Join(modifiedDir, diffFileName)
		diffFile, err := os.OpenFile(filepath.Clean(diffFilePath), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
		if err != nil {
			return errors.Wrapf(err, "unable to open file %q", diffFilePath)
		}
		if err := writeDiffToFile(filePathOriginal, filePathModified, diffFile); err != nil {
			return errors.Wrapf(err, "failed to write diff to file %q", diffFilePath)
		}
	}
	if len(out.Modified) != 0 {
		fmt.Printf("Modified objects are written to directory %q\n", modifiedDir)
	}

	return nil
}

func writeObjectToFile(filePath string, obj *unstructured.Unstructured) error {
	yaml, err := utilyaml.FromUnstructured([]unstructured.Unstructured{*obj})
	if err != nil {
		return errors.Wrap(err, "failed to convert object to yaml")
	}
	if err := os.WriteFile(filePath, yaml, 0600); err != nil {
		return errors.Wrapf(err, "failed to write yaml to file %q", filePath)
	}
	return nil
}

func convertToPtrSlice(objs []unstructured.Unstructured) []*unstructured.Unstructured {
	res := []*unstructured.Unstructured{}
	for i := range objs {
		res = append(res, &objs[i])
	}
	return res
}

func lessByKindAndName(a, b *unstructured.Unstructured) bool {
	if a.GetKind() == b.GetKind() {
		return a.GetName() < b.GetName()
	}
	return a.GetKind() < b.GetKind()
}

func addRow(table *tablewriter.Table, o *unstructured.Unstructured, action string, actionColor int) {
	table.Rich(
		[]string{
			o.GetNamespace(),
			o.GetKind(),
			o.GetName(),
			action,
		},
		[]tablewriter.Colors{
			{}, {}, {}, {actionColor},
		},
	)
}

// writeDiffToFile runs the detected diff program. `from` and `to` are the files to diff.
// The implementation is highly inspired by kubectl's DiffProgram implementation:
// ref: https://github.com/kubernetes/kubectl/blob/v0.24.3/pkg/cmd/diff/diff.go#L218
func writeDiffToFile(from, to string, out io.Writer) error {
	diff, cmd := getDiffCommand(from, to)
	cmd.SetStdout(out)

	if err := cmd.Run(); err != nil && !isDiffError(err) {
		return errors.Wrapf(err, "failed to run %q", diff)
	}
	return nil
}

func getDiffCommand(args ...string) (string, exec.Cmd) {
	diff := ""
	if envDiff := os.Getenv("KUBECTL_EXTERNAL_DIFF"); envDiff != "" {
		diffCommand := strings.Split(envDiff, " ")
		diff = diffCommand[0]

		if len(diffCommand) > 1 {
			// Regex accepts: Alphanumeric (case-insensitive), dash and equal
			isValidChar := regexp.MustCompile(`^[a-zA-Z0-9-=]+$`).MatchString
			for i := 1; i < len(diffCommand); i++ {
				if isValidChar(diffCommand[i]) {
					args = append(args, diffCommand[i])
				}
			}
		}
	} else {
		diff = "diff"
		args = append([]string{"-u", "-N"}, args...)
	}

	cmd := exec.New().Command(diff, args...)

	return diff, cmd
}

// diffError returns true if the status code is lower or equal to 1, false otherwise.
// This makes use of the exit code of diff programs which is 0 for no diff, 1 for
// modified and 2 for other errors.
func isDiffError(err error) bool {
	if err, ok := err.(exec.ExitError); ok && err.ExitStatus() <= 1 {
		return true
	}
	return false
}