[NET-6966] consul-template support for listing peerings

- new template function to access consul peerings in consul template.
- test cases for the same.

dependency/consul_peering.go

@@ -0,0 +1,197 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package dependency
+
+import (
+	"context"
+	"encoding/gob"
+	"fmt"
+	"github.com/hashicorp/consul/api"
+	"github.com/pkg/errors"
+	"log"
+	"net/url"
+	"regexp"
+	"sort"
+	"time"
+)
+
+var (
+	// Ensure implements
+	_ Dependency = (*ListPeeringQuery)(nil)
+
+	// ListPeeringQueryRe is the regular expression to use.
+	ListPeeringQueryRe = regexp.MustCompile(`\A` + queryRe + `\z`)
+)
+
+func init() {
+	gob.Register([]*Peering{})
+	gob.Register([]*PeeringStreamStatus{})
+	gob.Register([]*PeeringRemoteInfo{})
+}
+
+// ListPeeringQuery fetches all peering for a Consul cluster.
+// https://developer.hashicorp.com/consul/api-docs/peering#list-all-peerings
+type ListPeeringQuery struct {
+	stopCh chan struct{}
+
+	partition string
+}
+
+// Peering represent the response of the Consul peering API.
+type Peering struct {
+	ID                  string
+	Name                string
+	Partition           string
+	Meta                map[string]string
+	PeeringState        string
+	PeerID              string
+	PeerServerName      string
+	PeerServerAddresses []string
+	StreamStatus        PeeringStreamStatus
+	Remote              PeeringRemoteInfo
+}
+
+type PeeringStreamStatus struct {
+	ImportedServices []string
+	ExportedServices []string
+	LastHeartbeat    *time.Time
+	LastReceive      *time.Time
+	LastSend         *time.Time
+}
+
+type PeeringRemoteInfo struct {
+	Partition  string
+	Datacenter string
+}
+
+func NewListPeeringQuery(s string) (*ListPeeringQuery, error) {
+	if s != "" && !ListPeeringQueryRe.MatchString(s) {
+		return nil, fmt.Errorf("list.peering: invalid format: %q", s)
+	}
+
+	m := regexpMatch(ListPeeringQueryRe, s)
+
+	queryParams, err := GetConsulQueryOpts(m, "list.peering")
+	if err != nil {
+		return nil, err
+	}
+
+	return &ListPeeringQuery{
+		stopCh:    make(chan struct{}, 1),
+		partition: queryParams.Get(QueryPartition),
+	}, nil
+}
+
+func (l *ListPeeringQuery) Fetch(clients *ClientSet, opts *QueryOptions) (interface{}, *ResponseMetadata, error) {
+	select {
+	case <-l.stopCh:
+		return nil, nil, ErrStopped
+	default:
+	}
+
+	opts = opts.Merge(&QueryOptions{
+		ConsulPartition: l.partition,
+	})
+
+	log.Printf("[TRACE] %s: GET %s", l, &url.URL{
+		Path:     "/v1/peerings",
+		RawQuery: opts.String(),
+	})
+
+	// list peering is a blocking API, so making sure the ctx passed while calling it
+	// times out after the default wait time.
+	ctx, cancel := context.WithTimeout(context.Background(), DefaultContextTimeout)
+	defer cancel()
+
+	p, meta, err := clients.Consul().Peerings().List(ctx, opts.ToConsulOpts())
+	if err != nil {
+		return nil, nil, errors.Wrap(err, l.String())
+	}
+
+	log.Printf("[TRACE] %s: returned %d results", l, len(p))
+
+	peers := make([]*Peering, 0, len(p))
+	for _, peering := range p {
+		peers = append(peers, toPeering(peering))
+	}
+
+	// sort so that the result is deterministic
+	sort.Stable(ByPeer(peers))
+
+	rm := &ResponseMetadata{
+		LastIndex:   meta.LastIndex,
+		LastContact: meta.LastContact,
+	}
+
+	return peers, rm, nil
+}
+
+func toPeering(p *api.Peering) *Peering {
+	return &Peering{
+		ID:                  p.ID,
+		Name:                p.Name,
+		Partition:           p.Partition,
+		Meta:                p.Meta,
+		PeeringState:        fmt.Sprintf("%s", p.State),
+		PeerID:              p.PeerID,
+		PeerServerName:      p.PeerServerName,
+		PeerServerAddresses: p.PeerServerAddresses,
+		StreamStatus: PeeringStreamStatus{
+			ImportedServices: p.StreamStatus.ImportedServices,
+			ExportedServices: p.StreamStatus.ExportedServices,
+			LastHeartbeat:    p.StreamStatus.LastHeartbeat,
+			LastReceive:      p.StreamStatus.LastReceive,
+			LastSend:         p.StreamStatus.LastSend,
+		},
+		Remote: PeeringRemoteInfo{
+			Partition:  p.Remote.Partition,
+			Datacenter: p.Remote.Datacenter,
+		},
+	}
+}
+
+func (l *ListPeeringQuery) String() string {
+	partitionStr := l.partition
+
+	if len(partitionStr) > 0 {
+		partitionStr = fmt.Sprintf("?partition=%s", partitionStr)
+	} else {
+		return "list.peerings"
+	}
+
+	return fmt.Sprintf("list.peerings%s", partitionStr)
+}
+
+func (l *ListPeeringQuery) Stop() {
+	close(l.stopCh)
+}
+
+func (l *ListPeeringQuery) Type() Type {
+	return TypeConsul
+}
+
+func (l *ListPeeringQuery) CanShare() bool {
+	return false
+}
+
+// ByPeer is a sortable list of peerings in this order:
+// 1. State
+// 2. Partition
+// 3. Name
+type ByPeer []*Peering
+
+func (p ByPeer) Len() int      { return len(p) }
+func (p ByPeer) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
+
+// Less if peer names are cluster-2, cluster-12, cluster-1
+// our sorting will be cluster-1, cluster-12, cluster-2
+func (p ByPeer) Less(i, j int) bool {
+	if p[i].PeeringState == p[j].PeeringState {
+		if p[i].Partition == p[j].Partition {
+			return p[i].Name < p[j].Name
+		}
+		return p[i].Partition < p[j].Partition
+	}
+	return p[i].PeeringState < p[j].PeeringState
+}

dependency/consul_peering_test.go

@@ -0,0 +1,134 @@
+package dependency
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestListPeeringsQuery(t *testing.T) {
+	cases := []struct {
+		name string
+		i    string
+		exp  *ListPeeringQuery
+		err  bool
+	}{
+		{
+			"empty",
+			"",
+			&ListPeeringQuery{},
+			false,
+		},
+		{
+			"invalid query param (unsupported key)",
+			"?unsupported=foo",
+			nil,
+			true,
+		},
+		{
+			"peerings",
+			"peerings",
+			nil,
+			true,
+		},
+		{
+			"partition",
+			"?partition=foo",
+			&ListPeeringQuery{
+				partition: "foo",
+			},
+			false,
+		},
+	}
+
+	for i, tc := range cases {
+		t.Run(fmt.Sprintf("%d_%s", i, tc.name), func(t *testing.T) {
+			act, err := NewListPeeringQuery(tc.i)
+			if (err != nil) != tc.err {
+				t.Fatal(err)
+			}
+
+			if act != nil {
+				act.stopCh = nil
+			}
+
+			assert.Equal(t, tc.exp, act)
+		})
+	}
+}
+
+func TestListPeeringsQuery_Fetch(t *testing.T) {
+	cases := []struct {
+		name string
+		i    string
+		exp  []string
+	}{
+		{
+			"all",
+			"",
+			// the peering generated has random IDs,
+			// we can't assert on the full response,
+			// we can assert on the peering names though.
+			[]string{
+				"bar",
+				"foo",
+			},
+		},
+	}
+
+	for i, tc := range cases {
+		t.Run(fmt.Sprintf("%d_%s", i, tc.name), func(t *testing.T) {
+			p, err := NewListPeeringQuery(tc.i)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			res, _, err := p.Fetch(testClients, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if res == nil {
+				t.Fatalf("expected non-nil result")
+			}
+
+			peerNames := make([]string, 0)
+			for _, peering := range res.([]*Peering) {
+				peerNames = append(peerNames, peering.Name)
+			}
+
+			assert.Equal(t, tc.exp, peerNames)
+		})
+	}
+}
+
+func TestListPeeringsQuery_String(t *testing.T) {
+	cases := []struct {
+		name string
+		i    string
+		exp  string
+	}{
+		{
+			"empty",
+			"",
+			"list.peerings",
+		},
+		{
+			"partition",
+			"?partition=foo",
+			"list.peerings?partition=foo",
+		},
+	}
+
+	for i, tc := range cases {
+		t.Run(fmt.Sprintf("%d_%s", i, tc.name), func(t *testing.T) {
+			d, err := NewListPeeringQuery(tc.i)
+			if err != nil {
+				t.Fatal(err)
+			}
+			str := d.String()
+			assert.Equal(t, tc.exp, str)
+		})
+	}
+}

dependency/dependency.go

@@ -42,6 +42,11 @@ const (
 	TypeNomad
 )
 
+const (
+	// DefaultContextTimeout context wait timeout for blocking queries.
+	DefaultContextTimeout = 60 * time.Second
+)
+
 // Dependency is an interface for a dependency that Consul Template is capable
 // of watching.
 type Dependency interface {

dependency/dependency_test.go

@@ -4,6 +4,7 @@
 package dependency
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -124,6 +125,11 @@ func TestMain(m *testing.M) {
 		Fatalf("%v", err)
 	}
 
+	err := createConsulPeerings(clients)
+	if err != nil {
+		Fatalf("%v", err)
+	}
+
 	// Wait for Nomad initialization to finish
 	if err := <-nomadFuture; err != nil {
 		testConsul.Stop()
@@ -158,6 +164,22 @@ func TestMain(m *testing.M) {
 	os.Exit(exit)
 }
 
+func createConsulPeerings(clients *ClientSet) error {
+	generateReq := api.PeeringGenerateTokenRequest{PeerName: "foo"}
+	_, _, err := clients.consul.client.Peerings().GenerateToken(context.Background(), generateReq, &api.WriteOptions{})
+	if err != nil {
+		return err
+	}
+
+	generateReq = api.PeeringGenerateTokenRequest{PeerName: "bar"}
+	_, _, err = clients.consul.client.Peerings().GenerateToken(context.Background(), generateReq, &api.WriteOptions{})
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func runTestConsul(tb testutil.TestingTB) {
 	consul, err := testutil.NewTestServerConfigT(tb,
 		func(c *testutil.TestServerConfig) {