Exported services CLI and docs (#20331)

* Exported services CLI and docs

* Changelog added

* Added format option for pretty print

* Update command/exportedservices/exported_services.go

Co-authored-by: Ashesh Vidyut <134911583+absolutelightning@users.noreply.github.com>

* Addressing PR comments, moving the command under services category

* Add consumer peer and partition filter

* Adding bexpr filter, change format of data

---------

Co-authored-by: Ashesh Vidyut <134911583+absolutelightning@users.noreply.github.com>

.changelog/20331.txt

@@ -0,0 +1,3 @@
+```release-note:feature
+cli: Adds new command `exported-services` to list all services exported and their consumers. Refer to the [CLI docs](https://developer.hashicorp.com/consul/commands/exported-services) for more information.
+```

command/registry.go

@@ -122,6 +122,7 @@ import (
 	"github.com/hashicorp/consul/command/services"
 	svcsderegister "github.com/hashicorp/consul/command/services/deregister"
 	svcsexport "github.com/hashicorp/consul/command/services/export"
+	exportedservices "github.com/hashicorp/consul/command/services/exportedservices"
 	svcsregister "github.com/hashicorp/consul/command/services/register"
 	"github.com/hashicorp/consul/command/snapshot"
 	snapinspect "github.com/hashicorp/consul/command/snapshot/inspect"
@@ -264,6 +265,7 @@ func RegisteredCommands(ui cli.Ui) map[string]mcli.CommandFactory {
 		entry{"services register", func(ui cli.Ui) (cli.Command, error) { return svcsregister.New(ui), nil }},
 		entry{"services deregister", func(ui cli.Ui) (cli.Command, error) { return svcsderegister.New(ui), nil }},
 		entry{"services export", func(ui cli.Ui) (cli.Command, error) { return svcsexport.New(ui), nil }},
+		entry{"services exported-services", func(ui cli.Ui) (cli.Command, error) { return exportedservices.New(ui), nil }},
 		entry{"snapshot", func(cli.Ui) (cli.Command, error) { return snapshot.New(), nil }},
 		entry{"snapshot inspect", func(ui cli.Ui) (cli.Command, error) { return snapinspect.New(ui), nil }},
 		entry{"snapshot restore", func(ui cli.Ui) (cli.Command, error) { return snaprestore.New(ui), nil }},

command/services/exportedservices/exported_services.go

@@ -0,0 +1,176 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package exportedservices
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/mitchellh/cli"
+
+	"github.com/hashicorp/consul/api"
+	"github.com/hashicorp/consul/command/flags"
+	"github.com/hashicorp/go-bexpr"
+	"github.com/ryanuber/columnize"
+)
+
+const (
+	PrettyFormat string = "pretty"
+	JSONFormat   string = "json"
+)
+
+func getSupportedFormats() []string {
+	return []string{PrettyFormat, JSONFormat}
+}
+
+func formatIsValid(f string) bool {
+	for _, format := range getSupportedFormats() {
+		if f == format {
+			return true
+		}
+	}
+	return false
+
+}
+
+func New(ui cli.Ui) *cmd {
+	c := &cmd{UI: ui}
+	c.init()
+	return c
+}
+
+type cmd struct {
+	UI    cli.Ui
+	flags *flag.FlagSet
+	http  *flags.HTTPFlags
+	help  string
+
+	format string
+	filter string
+}
+
+func (c *cmd) init() {
+	c.flags = flag.NewFlagSet("", flag.ContinueOnError)
+
+	c.flags.StringVar(
+		&c.format,
+		"format",
+		PrettyFormat,
+		fmt.Sprintf("Output format {%s} (default: %s)", strings.Join(getSupportedFormats(), "|"), PrettyFormat),
+	)
+
+	c.flags.StringVar(&c.filter, "filter", "", "go-bexpr filter string to filter the response")
+
+	c.http = &flags.HTTPFlags{}
+	flags.Merge(c.flags, c.http.ClientFlags())
+	flags.Merge(c.flags, c.http.ServerFlags())
+	flags.Merge(c.flags, c.http.PartitionFlag())
+	c.help = flags.Usage(help, c.flags)
+}
+
+func (c *cmd) Run(args []string) int {
+	if err := c.flags.Parse(args); err != nil {
+		return 1
+	}
+
+	if !formatIsValid(c.format) {
+		c.UI.Error(fmt.Sprintf("Invalid format, valid formats are {%s}", strings.Join(getSupportedFormats(), "|")))
+		return 1
+	}
+
+	client, err := c.http.APIClient()
+	if err != nil {
+		c.UI.Error(fmt.Sprintf("Error connect to Consul agent: %s", err))
+		return 1
+	}
+
+	exportedServices, _, err := client.ExportedServices(nil)
+	if err != nil {
+		c.UI.Error(fmt.Sprintf("Error reading exported services: %v", err))
+		return 1
+	}
+
+	var filterType []api.ResolvedExportedService
+	filter, err := bexpr.CreateFilter(c.filter, nil, filterType)
+	if err != nil {
+		c.UI.Error(fmt.Sprintf("Error while creating filter: %s", err))
+		return 1
+	}
+
+	raw, err := filter.Execute(exportedServices)
+	if err != nil {
+		c.UI.Error(fmt.Sprintf("Error while filtering response: %s", err))
+		return 1
+	}
+
+	filteredServices := raw.([]api.ResolvedExportedService)
+
+	if len(filteredServices) == 0 {
+		c.UI.Info("No exported services found")
+		return 0
+	}
+
+	if c.format == JSONFormat {
+		output, err := json.MarshalIndent(filteredServices, "", "    ")
+		if err != nil {
+			c.UI.Error(fmt.Sprintf("Error marshalling JSON: %s", err))
+			return 1
+		}
+		c.UI.Output(string(output))
+		return 0
+	}
+
+	c.UI.Output(formatExportedServices(filteredServices))
+
+	return 0
+}
+
+func formatExportedServices(services []api.ResolvedExportedService) string {
+	result := make([]string, 0, len(services)+1)
+
+	if services[0].Partition != "" {
+		result = append(result, "Service\x1fPartition\x1fNamespace\x1fConsumer Peers\x1fConsumer Partitions")
+	} else {
+		result = append(result, "Service\x1fConsumer Peers")
+	}
+
+	for _, expService := range services {
+		row := ""
+		peers := strings.Join(expService.Consumers.Peers, ", ")
+		partitions := strings.Join(expService.Consumers.Partitions, ", ")
+		if expService.Partition != "" {
+			row = fmt.Sprintf("%s\x1f%s\x1f%s\x1f%s\x1f%s", expService.Service, expService.Partition, expService.Namespace, peers, partitions)
+		} else {
+			row = fmt.Sprintf("%s\x1f%s", expService.Service, peers)
+		}
+
+		result = append(result, row)
+
+	}
+
+	return columnize.Format(result, &columnize.Config{Delim: string([]byte{0x1f})})
+}
+
+func (c *cmd) Synopsis() string {
+	return synopsis
+}
+
+func (c *cmd) Help() string {
+	return flags.Usage(c.help, nil)
+}
+
+const (
+	synopsis = "Lists exported services"
+	help     = `
+Usage: consul services exported-services [options]
+
+  Lists all the exported services and their consumers. Wildcards and sameness groups(Enterprise) are expanded.
+
+  Example:
+
+    $ consul services exported-services
+`
+)