Backport of member cli: add -filter expression to flags into release/1.16.x (#18276)

* backport of commit fe571c6c3e88e828e68172c1eb22b338e614635b

* backport of commit 779901b6cd428e1b5116a9fe33ff5f88ce27e88b

* backport of commit adfa76146adabd4a6ed54f067e6e3e886d5c198f

---------

Co-authored-by: cskh <hui.kang@hashicorp.com>

.changelog/18223.txt

@@ -0,0 +1,3 @@
+```release-note:feature
+cli: `consul members` command uses `-filter` expression to filter members based on bexpr.
+```

agent/agent_endpoint.go

@@ -621,6 +621,21 @@ func (s *HTTPHandlers) AgentMembers(resp http.ResponseWriter, req *http.Request)
 		}
 	}
 
+	// filter the members by parsed filter expression
+	var filterExpression string
+	s.parseFilter(req, &filterExpression)
+	if filterExpression != "" {
+		filter, err := bexpr.CreateFilter(filterExpression, nil, members)
+		if err != nil {
+			return nil, err
+		}
+		raw, err := filter.Execute(members)
+		if err != nil {
+			return nil, err
+		}
+		members = raw.([]serf.Member)
+	}
+
 	total := len(members)
 	if err := s.agent.filterMembers(token, &members); err != nil {
 		return nil, err

api/agent.go

@@ -274,6 +274,8 @@ type MembersOpts struct {
 	// Segment is the LAN segment to show members for. Setting this to the
 	// AllSegments value above will show members in all segments.
 	Segment string
+
+	Filter string
 }
 
 // AgentServiceRegistration is used to register a new service
@@ -790,6 +792,10 @@ func (a *Agent) MembersOpts(opts MembersOpts) ([]*AgentMember, error) {
 		r.params.Set("wan", "1")
 	}
 
+	if opts.Filter != "" {
+		r.params.Set("filter", opts.Filter)
+	}
+
 	_, resp, err := a.c.doRequest(r)
 	if err != nil {
 		return nil, err

api/agent_test.go

@@ -155,6 +155,16 @@ func TestAPI_AgentMembersOpts(t *testing.T) {
 	if len(members) != 2 {
 		t.Fatalf("bad: %v", members)
 	}
+
+	members, err = agent.MembersOpts(MembersOpts{
+		WAN:    true,
+		Filter: `Tags["dc"] == dc2`,
+	})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	require.Equal(t, 1, len(members))
 }
 
 func TestAPI_AgentMembers(t *testing.T) {

command/members/members.go

@@ -33,6 +33,7 @@ type cmd struct {
 	wan          bool
 	statusFilter string
 	segment      string
+	filter       string
 }
 
 func New(ui cli.Ui) *cmd {
@@ -54,6 +55,7 @@ func (c *cmd) init() {
 	c.flags.StringVar(&c.segment, "segment", consulapi.AllSegments,
 		"(Enterprise-only) If provided, output is filtered to only nodes in"+
 			"the given segment.")
+	c.flags.StringVar(&c.filter, "filter", "", "Filter to use with the request")
 
 	c.http = &flags.HTTPFlags{}
 	flags.Merge(c.flags, c.http.ClientFlags())
@@ -83,6 +85,7 @@ func (c *cmd) Run(args []string) int {
 	opts := consulapi.MembersOpts{
 		Segment: c.segment,
 		WAN:     c.wan,
+		Filter:  c.filter,
 	}
 	members, err := client.Agent().MembersOpts(opts)
 	if err != nil {

website/content/commands/members.mdx

@@ -48,6 +48,12 @@ Usage: `consul members [options]`
   in the WAN gossip pool. These are generally all the server nodes in
   each datacenter.
 
+- `-filter=<filter>` - Expression to use for filtering the results,
+  e.g., `-filter='Tags["dc"] == dc2'`.
+  See the [`/catalog/nodes` API documentation](/consul/api-docs/catalog#filtering) for a
+  description of what is filterable.
+
+
 #### Enterprise Options
 
 @include 'http_api_partition_options.mdx'