WIP: use stable client indexes to pick target vtgates

Signed-off-by: Henry Robinson <hrobinson@slack-corp.com>

Author: henryr

go/vt/vtgateproxy/discovery.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"io"
 	"math/rand"
+	"net/http"
 	"os"
 	"sort"
 	"sync"
@@ -319,11 +320,16 @@ func (b *JSONGateResolverBuilder) parse() (bool, error) {
 	// target lock and then comparing the previous targets with the current
 	// targets and only resetting pools which disappear.
 	targetCount.ResetAll()
-
+	idx := getClientIndex()
 	for poolType := range targets {
 		b.sorter.shuffleSort(targets[poolType], b.affinityField, b.affinityValue)
 		if len(targets[poolType]) > *numConnections {
-			targets[poolType] = targets[poolType][:b.numConnections]
+			targetPool := []targetHost{}
+			for i := 0; i < 4; i++ {
+				targetPool = append(targetPool, targets[poolType][(idx+i)%len(targets[poolType])])
+			}
+			log.Infof("My index is: %d, picking %+v", idx, targetPool)
+			targets[poolType] = targetPool
 		}
 		targetCount.Set(poolType, int64(len(targets[poolType])))
 	}
@@ -393,6 +399,66 @@ func (s *shuffleSorter) shuffleSort(targets []targetHost, affinityField, affinit
 	}
 }
 
+func getWebappDiscovery() *RotorJson {
+	payload := `{"node":{"cluster":"webapp"}, "resource_names":["hhvm-metrics@dev-us-east-1"]}`
+	res, err := http.Post("http://rotor-http-dev-us-east-1.internal.ec2.tinyspeck.com:50001/v3/discovery:endpoints", "application/json", bytes.NewBuffer([]byte(payload)))
+	if err != nil {
+		return nil
+	}
+	//	fmt.Println("Non-nil response")
+	if res.StatusCode != 200 {
+		return nil
+	}
+	//	fmt.Println("200 response")
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		return nil
+	}
+	//	fmt.Printf("Unmarshalling %+v\n", string(body))
+	result := RotorJson{}
+	json.Unmarshal(body, &result)
+	//	fmt.Printf("%+v\n", result)
+	return &result
+}
+
+func getHosts() []string {
+	discovery := getWebappDiscovery()
+	nodenames := []string{}
+	for _, r := range discovery.Resources {
+		for _, e := range r.Endpoints {
+			for _, lb := range e.LBEndpoints {
+				node := lb.Metadata.FilterMetadata.EnvoyLB
+				nodenames = append(nodenames, node.NodeName)
+				fmt.Printf("Nodename: %+v\n", node.NodeName)
+			}
+		}
+	}
+
+	return nodenames
+}
+
+func getClientIndex() int {
+	nodenames := getHosts()
+	sort.Strings(nodenames)
+	hostname, err := os.Hostname()
+	fmt.Printf("Hostname: %s\n", hostname)
+	if err != nil {
+		return -1
+	}
+
+	for i, n := range nodenames {
+		if n == hostname {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func DoTest() int {
+	return getClientIndex()
+}
+
 // Update the current list of hosts for the given resolver
 func (b *JSONGateResolverBuilder) update(r *JSONGateResolver) error {
 	log.V(100).Infof("resolving target %s to %d connections\n", r.target.URL.String(), *numConnections)

go/vt/vtgateproxy/rotor_json.go

@@ -0,0 +1,185 @@
+package vtgateproxy
+
+type RotorJson struct {
+	VersionInfo  string       `json:"version_info"`
+	Resources    []Resource   `json:"resources"`
+	TypeURL      string       `json:"type_url"`
+	ControlPlane ControlPlane `json:"control_plane"`
+}
+
+type ControlPlane struct {
+	Identifier string `json:"identifier"`
+}
+
+type Resource struct {
+	Type        string            `json:"@type"`
+	ClusterName string            `json:"cluster_name"`
+	Endpoints   []EndpointElement `json:"endpoints"`
+}
+
+type EndpointElement struct {
+	LBEndpoints []LBEndpoint `json:"lb_endpoints"`
+}
+
+type LBEndpoint struct {
+	Endpoint     LBEndpointEndpoint `json:"endpoint"`
+	HealthStatus HealthStatus       `json:"health_status"`
+	Metadata     Metadata           `json:"metadata"`
+}
+
+type LBEndpointEndpoint struct {
+	Address Address `json:"address"`
+}
+
+type Address struct {
+	SocketAddress SocketAddress `json:"socket_address"`
+}
+
+type SocketAddress struct {
+	Address   string `json:"address"`
+	PortValue int64  `json:"port_value"`
+}
+
+type Metadata struct {
+	FilterMetadata FilterMetadata `json:"filter_metadata"`
+}
+
+type FilterMetadata struct {
+	EnvoyLB EnvoyLB `json:"envoy.lb"`
+}
+
+type EnvoyLB struct {
+	Consul                   Consul            `json:"consul"`
+	NodeAddress              string            `json:"node-address"`
+	NodeHealth               NodeHealth        `json:"node-health"`
+	NodeID                   string            `json:"node-id"`
+	NodeName                 string            `json:"node-name"`
+	NodeASG                  ASG               `json:"node:asg"`
+	NodeAz                   NodeAz            `json:"node:az"`
+	NodeAzID                 AzID              `json:"node:az_id"`
+	NodeConsulNetworkSegment string            `json:"node:consul-network-segment"`
+	NodeConsulVersion        ConsulVersion     `json:"node:consul-version"`
+	NodeEnv                  Env               `json:"node:env"`
+	NodeLSBRelease           string            `json:"node:lsb_release"`
+	NodeNebulaAddress        string            `json:"node:nebula_address"`
+	NodeOmniServiceID        string            `json:"node:omni_service_id"`
+	NodePlatform             Platform          `json:"node:platform"`
+	NodeProvider             Provider          `json:"node:provider"`
+	NodeRegion               Region            `json:"node:region"`
+	NodeRole                 Role              `json:"node:role"`
+	TagDatacenter            TagDatacenterEnum `json:"tag:datacenter"`
+	TagLegacyDc              TagDatacenterEnum `json:"tag:legacy_dc"`
+}
+
+type Consul struct {
+	NodeMeta NodeMeta `json:"nodeMeta"`
+	Tag      Tag      `json:"tag"`
+}
+
+type NodeMeta struct {
+	ASG                  ASG           `json:"asg"`
+	Az                   NodeAz        `json:"az"`
+	AzID                 AzID          `json:"az_id"`
+	ConsulNetworkSegment string        `json:"consul-network-segment"`
+	ConsulVersion        ConsulVersion `json:"consul-version"`
+	Env                  Env           `json:"env"`
+	LSBRelease           string        `json:"lsb_release"`
+	NebulaAddress        string        `json:"nebula_address"`
+	OmniServiceID        string        `json:"omni_service_id"`
+	Platform             Platform      `json:"platform"`
+	Provider             Provider      `json:"provider"`
+	Region               Region        `json:"region"`
+	Role                 Role          `json:"role"`
+}
+
+type Tag struct {
+	DatacenterDevUsEast1 string `json:"datacenter:dev-us-east-1"`
+	LegacyDcDevUsEast1   string `json:"legacy_dc:dev-us-east-1"`
+}
+
+type HealthStatus string
+
+const (
+	Healthy HealthStatus = "HEALTHY"
+)
+
+type ASG string
+
+const (
+	ASGRdevCanvasWebapp               ASG = "rdev-canvas-webapp"
+	DevContainersPoolLargeWhitecastle ASG = "dev-containers-pool-large-whitecastle"
+	DevContainersPoolTestWhitecastle  ASG = "dev-containers-pool-test-whitecastle"
+	DevContainersPoolWhitecastle      ASG = "dev-containers-pool-whitecastle"
+	Empty                             ASG = ""
+	QAEnvContainerPoolWc              ASG = "qa-env-container-pool-wc"
+	QAEnvSandboxContainerPoolWc       ASG = "qa-env-sandbox-container-pool-wc"
+)
+
+type NodeAz string
+
+const (
+	UsEast1A NodeAz = "us-east-1a"
+	UsEast1B NodeAz = "us-east-1b"
+	UsEast1C NodeAz = "us-east-1c"
+	UsEast1D NodeAz = "us-east-1d"
+)
+
+type AzID string
+
+const (
+	Use1Az1 AzID = "use1-az1"
+	Use1Az2 AzID = "use1-az2"
+	Use1Az4 AzID = "use1-az4"
+	Use1Az6 AzID = "use1-az6"
+)
+
+type ConsulVersion string
+
+const (
+	The1201Slack16 ConsulVersion = "1.20.1+slack.16"
+)
+
+type Env string
+
+const (
+	Dev Env = "dev"
+)
+
+type Platform string
+
+const (
+	Chef Platform = "chef"
+)
+
+type Provider string
+
+const (
+	Ec2 Provider = "ec2"
+)
+
+type Region string
+
+const (
+	UsEast1 Region = "us-east-1"
+)
+
+type Role string
+
+const (
+	RoleRdevCanvasWebapp       Role = "rdev-canvas-webapp"
+	SlackDevContainer          Role = "slack-dev-container"
+	SlackQAEnvContainer        Role = "slack-qa-env-container"
+	SlackQAEnvSandboxContainer Role = "slack-qa-env-sandbox-container"
+)
+
+type NodeHealth string
+
+const (
+	Passing NodeHealth = "passing"
+)
+
+type TagDatacenterEnum string
+
+const (
+	DevUsEast1 TagDatacenterEnum = "dev-us-east-1"
+)