Ruler: optimised <prefix>/api/v1/rules and <prefix>/api/v1/alerts (co…

…rtexproject#3916)

* Use a grpc clients pool in the ruler

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Concurrently fetch rules from all rulers

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Added subservices manager

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Fixed Rules() grpc call

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Added integration test

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Added CHANGELOG entry

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Addressed review comments

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Fixed CHANGELOG

Signed-off-by: Marco Pracucci <marco@pracucci.com>

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## master / unreleased
 
+* [ENHANCEMENT] Ruler: optimized `<prefix>/api/v1/rules` and `<prefix>/api/v1/alerts` when ruler sharding is enabled. #3916
+* [ENHANCEMENT] Ruler: added the following metrics when ruler sharding is enabled: #3916
+  * `cortex_ruler_clients`
+  * `cortex_ruler_client_request_duration_seconds`
+
 ## 1.8.0 in progress
 
 * [CHANGE] Alertmanager: Don't expose cluster information to tenants via the `/alertmanager/api/v1/status` API endpoint when operating with clustering enabled.

integration/configs.go

@@ -168,6 +168,14 @@ var (
 		}
 	}
 
+	RulerShardingFlags = func(consulAddress string) map[string]string {
+		return map[string]string{
+			"-ruler.enable-sharding":      "true",
+			"-ruler.ring.store":           "consul",
+			"-ruler.ring.consul.hostname": consulAddress,
+		}
+	}
+
 	BlocksStorageFlags = func() map[string]string {
 		return map[string]string{
 			"-store.engine":                                 blocksStorageEngine,

integration/e2ecortex/client.go

@@ -23,6 +23,8 @@ import (
 	"github.com/prometheus/prometheus/pkg/rulefmt"
 	"github.com/prometheus/prometheus/prompb"
 	yaml "gopkg.in/yaml.v3"
+
+	"github.com/cortexproject/cortex/pkg/ruler"
 )
 
 var (
@@ -213,7 +215,49 @@ type ServerStatus struct {
 	} `json:"data"`
 }
 
-// GetRuleGroups gets the status of an alertmanager instance
+// GetPrometheusRules fetches the rules from the Prometheus endpoint /api/v1/rules.
+func (c *Client) GetPrometheusRules() ([]*ruler.RuleGroup, error) {
+	// Create HTTP request
+	req, err := http.NewRequest("GET", fmt.Sprintf("http://%s/api/prom/api/v1/rules", c.rulerAddress), nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("X-Scope-OrgID", c.orgID)
+
+	ctx, cancel := context.WithTimeout(context.Background(), c.timeout)
+	defer cancel()
+
+	// Execute HTTP request
+	res, err := c.httpClient.Do(req.WithContext(ctx))
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	// Decode the response.
+	type response struct {
+		Status string              `json:"status"`
+		Data   ruler.RuleDiscovery `json:"data"`
+	}
+
+	decoded := &response{}
+	if err := json.Unmarshal(body, decoded); err != nil {
+		return nil, err
+	}
+
+	if decoded.Status != "success" {
+		return nil, fmt.Errorf("unexpected response status '%s'", decoded.Status)
+	}
+
+	return decoded.Data.RuleGroups, nil
+}
+
+// GetRuleGroups gets the configured rule groups from the ruler.
 func (c *Client) GetRuleGroups() (map[string][]rulefmt.RuleGroup, error) {
 	// Create HTTP request
 	req, err := http.NewRequest("GET", fmt.Sprintf("http://%s/api/prom/rules", c.rulerAddress), nil)
@@ -247,7 +291,7 @@ func (c *Client) GetRuleGroups() (map[string][]rulefmt.RuleGroup, error) {
 	return rgs, nil
 }
 
-// SetRuleGroup gets the status of an alertmanager instance
+// SetRuleGroup configures the provided rulegroup to the ruler.
 func (c *Client) SetRuleGroup(rulegroup rulefmt.RuleGroup, namespace string) error {
 	// Create write request
 	data, err := yaml.Marshal(rulegroup)
@@ -277,7 +321,7 @@ func (c *Client) SetRuleGroup(rulegroup rulefmt.RuleGroup, namespace string) err
 	return nil
 }
 
-// DeleteRuleGroup gets the status of an alertmanager instance
+// DeleteRuleGroup deletes a rule group.
 func (c *Client) DeleteRuleGroup(namespace string, groupName string) error {
 	// Create HTTP request
 	req, err := http.NewRequest("DELETE", fmt.Sprintf("http://%s/api/prom/rules/%s/%s", c.rulerAddress, url.PathEscape(namespace), url.PathEscape(groupName)), nil)

integration/ruler_test.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -20,6 +21,7 @@ import (
 	"github.com/prometheus/prometheus/pkg/rulefmt"
 	"github.com/prometheus/prometheus/pkg/value"
 	"github.com/prometheus/prometheus/prompb"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"gopkg.in/yaml.v3"
 
@@ -301,7 +303,87 @@ func TestRulerEvaluationDelay(t *testing.T) {
 		}
 	}
 	require.Equal(t, len(series.Samples), inputPos, "expect to have returned all evaluations")
+}
+
+func TestRulerSharding(t *testing.T) {
+	const numRulesGroups = 100
+
+	s, err := e2e.NewScenario(networkName)
+	require.NoError(t, err)
+	defer s.Close()
+
+	// Generate multiple rule groups, with 1 rule each.
+	ruleGroups := make([]rulefmt.RuleGroup, numRulesGroups)
+	expectedNames := make([]string, numRulesGroups)
+	for i := 0; i < numRulesGroups; i++ {
+		var recordNode yaml.Node
+		var exprNode yaml.Node
+
+		recordNode.SetString(fmt.Sprintf("rule_%d", i))
+		exprNode.SetString(strconv.Itoa(i))
+		ruleName := fmt.Sprintf("test_%d", i)
+
+		expectedNames[i] = ruleName
+		ruleGroups[i] = rulefmt.RuleGroup{
+			Name:     ruleName,
+			Interval: 60,
+			Rules: []rulefmt.RuleNode{{
+				Record: recordNode,
+				Expr:   exprNode,
+			}},
+		}
+	}
+
+	// Start dependencies.
+	consul := e2edb.NewConsul()
+	minio := e2edb.NewMinio(9000, rulestoreBucketName)
+	require.NoError(t, s.StartAndWaitReady(consul, minio))
 
+	// Configure the ruler.
+	rulerFlags := mergeFlags(
+		BlocksStorageFlags(),
+		RulerFlags(false),
+		RulerShardingFlags(consul.NetworkHTTPEndpoint()),
+		map[string]string{
+			// Since we're not going to run any rule, we don't need the
+			// store-gateway to be configured to a valid address.
+			"-querier.store-gateway-addresses": "localhost:12345",
+			// Enable the bucket index so we can skip the initial bucket scan.
+			"-blocks-storage.bucket-store.bucket-index.enabled": "true",
+		},
+	)
+
+	// Start rulers.
+	ruler1 := e2ecortex.NewRuler("ruler-1", rulerFlags, "")
+	ruler2 := e2ecortex.NewRuler("ruler-2", rulerFlags, "")
+	rulers := e2ecortex.NewCompositeCortexService(ruler1, ruler2)
+	require.NoError(t, s.StartAndWaitReady(ruler1, ruler2))
+
+	// Upload rule groups to one of the rulers.
+	c, err := e2ecortex.NewClient("", "", "", ruler1.HTTPEndpoint(), "user-1")
+	require.NoError(t, err)
+
+	for _, ruleGroup := range ruleGroups {
+		require.NoError(t, c.SetRuleGroup(ruleGroup, "test"))
+	}
+
+	// Wait until rulers have loaded all rules.
+	require.NoError(t, rulers.WaitSumMetricsWithOptions(e2e.Equals(numRulesGroups), []string{"cortex_prometheus_rule_group_rules"}, e2e.WaitMissingMetrics))
+
+	// Since rulers have loaded all rules, we expect that rules have been sharded
+	// between the two rulers.
+	require.NoError(t, ruler1.WaitSumMetrics(e2e.Less(numRulesGroups), "cortex_prometheus_rule_group_rules"))
+	require.NoError(t, ruler2.WaitSumMetrics(e2e.Less(numRulesGroups), "cortex_prometheus_rule_group_rules"))
+
+	// Fetch the rules and ensure they match the configured ones.
+	actualGroups, err := c.GetPrometheusRules()
+	require.NoError(t, err)
+
+	var actualNames []string
+	for _, group := range actualGroups {
+		actualNames = append(actualNames, group.Name)
+	}
+	assert.ElementsMatch(t, expectedNames, actualNames)
 }
 
 func TestRulerAlertmanager(t *testing.T) {

pkg/ruler/api_test.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	io "io"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"

pkg/ruler/client_pool.go

@@ -0,0 +1,79 @@
+package ruler
+
+import (
+	"time"
+
+	"github.com/go-kit/kit/log"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/health/grpc_health_v1"
+
+	"github.com/cortexproject/cortex/pkg/ring/client"
+	"github.com/cortexproject/cortex/pkg/util/grpcclient"
+)
+
+func newRulerClientPool(clientCfg grpcclient.Config, logger log.Logger, reg prometheus.Registerer) *client.Pool {
+	// We prefer sane defaults instead of exposing further config options.
+	poolCfg := client.PoolConfig{
+		CheckInterval:      time.Minute,
+		HealthCheckEnabled: true,
+		HealthCheckTimeout: 10 * time.Second,
+	}
+
+	clientsCount := promauto.With(reg).NewGauge(prometheus.GaugeOpts{
+		Name: "cortex_ruler_clients",
+		Help: "The current number of ruler clients in the pool.",
+	})
+
+	return client.NewPool("ruler", poolCfg, nil, newRulerClientFactory(clientCfg, reg), clientsCount, logger)
+}
+
+func newRulerClientFactory(clientCfg grpcclient.Config, reg prometheus.Registerer) client.PoolFactory {
+	requestDuration := promauto.With(reg).NewHistogramVec(prometheus.HistogramOpts{
+		Name:    "cortex_ruler_client_request_duration_seconds",
+		Help:    "Time spent executing requests to the ruler.",
+		Buckets: prometheus.ExponentialBuckets(0.008, 4, 7),
+	}, []string{"operation", "status_code"})
+
+	return func(addr string) (client.PoolClient, error) {
+		return dialRulerClient(clientCfg, addr, requestDuration)
+	}
+}
+
+func dialRulerClient(clientCfg grpcclient.Config, addr string, requestDuration *prometheus.HistogramVec) (*rulerExtendedClient, error) {
+	opts, err := clientCfg.DialOption(grpcclient.Instrument(requestDuration))
+	if err != nil {
+		return nil, err
+	}
+
+	conn, err := grpc.Dial(addr, opts...)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to dial ruler %s", addr)
+	}
+
+	return &rulerExtendedClient{
+		RulerClient:  NewRulerClient(conn),
+		HealthClient: grpc_health_v1.NewHealthClient(conn),
+		conn:         conn,
+	}, nil
+}
+
+type rulerExtendedClient struct {
+	RulerClient
+	grpc_health_v1.HealthClient
+	conn *grpc.ClientConn
+}
+
+func (c *rulerExtendedClient) Close() error {
+	return c.conn.Close()
+}
+
+func (c *rulerExtendedClient) String() string {
+	return c.RemoteAddress()
+}
+
+func (c *rulerExtendedClient) RemoteAddress() string {
+	return c.conn.Target()
+}

pkg/ruler/client_pool_test.go

@@ -0,0 +1,68 @@
+package ruler
+
+import (
+	"context"
+	"net"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/weaveworks/common/user"
+	"google.golang.org/grpc"
+
+	"github.com/cortexproject/cortex/pkg/util/flagext"
+	"github.com/cortexproject/cortex/pkg/util/grpcclient"
+)
+
+func Test_newRulerClientFactory(t *testing.T) {
+	// Create a GRPC server used to query the mocked service.
+	grpcServer := grpc.NewServer()
+	defer grpcServer.GracefulStop()
+
+	srv := &mockRulerServer{}
+	RegisterRulerServer(grpcServer, srv)
+
+	listener, err := net.Listen("tcp", "localhost:0")
+	require.NoError(t, err)
+
+	go func() {
+		require.NoError(t, grpcServer.Serve(listener))
+	}()
+
+	// Create a client factory and query back the mocked service
+	// with different clients.
+	cfg := grpcclient.Config{}
+	flagext.DefaultValues(&cfg)
+
+	reg := prometheus.NewPedanticRegistry()
+	factory := newRulerClientFactory(cfg, reg)
+
+	for i := 0; i < 2; i++ {
+		client, err := factory(listener.Addr().String())
+		require.NoError(t, err)
+		defer client.Close() //nolint:errcheck
+
+		ctx := user.InjectOrgID(context.Background(), "test")
+		_, err = client.(*rulerExtendedClient).Rules(ctx, &RulesRequest{})
+		assert.NoError(t, err)
+	}
+
+	// Assert on the request duration metric, but since it's a duration histogram and
+	// we can't predict the exact time it took, we need to workaround it.
+	metrics, err := reg.Gather()
+	require.NoError(t, err)
+
+	assert.Len(t, metrics, 1)
+	assert.Equal(t, "cortex_ruler_client_request_duration_seconds", metrics[0].GetName())
+	assert.Equal(t, dto.MetricType_HISTOGRAM, metrics[0].GetType())
+	assert.Len(t, metrics[0].GetMetric(), 1)
+	assert.Equal(t, uint64(2), metrics[0].GetMetric()[0].GetHistogram().GetSampleCount())
+}
+
+type mockRulerServer struct{}
+
+func (m *mockRulerServer) Rules(context.Context, *RulesRequest) (*RulesResponse, error) {
+	return &RulesResponse{}, nil
+}