antelope-api-healthcheck/src/server.go

package main

import (
    "fmt"
	"time"
	"strings"
	"strconv"
	"internal/log"
	"internal/haproxy"
	"internal/eosapi"
	"internal/utils"
    "github.com/firstrow/tcp_server"
)

//  check_api - Validates head block time.
// ---------------------------------------------------------
func check_api(p eosapi.ReqParams, block_time float64) (haproxy.HealthCheckStatus, string) {

	info, err := eosapi.GetInfo(p)
	if err != nil {
		msg := fmt.Sprintf("%s", err);
		return haproxy.HealthCheckFailed, msg
	}

	// Check HTTP Status Code
	if info.HTTPStatusCode > 299 {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because %v was received from backend", info.HTTPStatusCode)
	}

	// Validate head block.
	now  := time.Now().In(time.UTC)
	diff := now.Sub(info.HeadBlockTime).Seconds()

	if diff > block_time {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because head block is lagging %.0f seconds", diff)
	} else if diff < -block_time {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because head block is %.0f seconds into the future", diff)
	}
	return haproxy.HealthCheckUp, "OK"
}

//  check_api_v2 (hyperion)
//    Validates block num diff between
//    nodeos and elasticsearch
// ---------------------------------------------------------
func check_api_v2(p eosapi.ReqParams, offset int64) (haproxy.HealthCheckStatus, string) {

	health, err := eosapi.GetHealth(p)
	if err != nil {
		msg := fmt.Sprintf("%s", err);
		return haproxy.HealthCheckFailed, msg
	}

    // Check HTTP Status Code
    if health.HTTPStatusCode > 299 {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because %v was received from backend", health.HTTPStatusCode)
    }

	// Fetch elasticsearch and nodeos block numbers from json.
	var es_block int64 = 0
	var node_block int64 = 0

	for _, v := range health.Health {
		if v.Name == "Elasticsearch" {
			es_block = utils.JsonGetInt64(v.Data["last_indexed_block"])
		} else if v.Name == "NodeosRPC" {
			node_block = utils.JsonGetInt64(v.Data["head_block_num"])
		}
	}

	// Error out if ether or both are zero.
	if es_block == 0 || node_block == 0 {
		msg := fmt.Sprintf("Failed to get Elasticsearch and/or nodeos " +
			"block numbers (es: %d, eos: %d)", es_block, node_block)
		return haproxy.HealthCheckFailed, msg
	}

	// Check if ES is behind or in the future.
	diff := node_block - es_block;
	if diff > offset {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because Elastic is %d blocks behind", diff)
	} else if diff < -offset {
		return haproxy.HealthCheckDown,
			fmt.Sprintf("Taking offline because Elastic is %d blocks into the future", -1 * diff)
	}
	return haproxy.HealthCheckUp, "OK"
}

//  onTcpMessage callback function
// ---------------------------------------------------------

func onTcpMessage(c *tcp_server.Client, args string) {
	params := eosapi.ReqParams{}
	var block_time int = 10
	var version string = "v1"

	// Parse arguments.
	// -------------------
	split := strings.Split(strings.TrimSpace(args), "|")

	// 1. url (scheme + ip/domain + port)
	params.Url = split[0]

	// 2. Block time.
	if len(split) > 1 {
		p, err := strconv.ParseInt(split[1], 10, 32)
		if err == nil {
			block_time = int(p)
		}
	}

	// 3. Version
	if len(split) > 2 {
		version = split[2]
	}

	// 4. Host
	if len(split) > 3 {
		params.Host = split[3]
	}

	// Check api.
	// -------------------
	var status haproxy.HealthCheckStatus
	var msg string

	if version == "v2" {
		status, msg = check_api_v2(params, int64(block_time / 2))
	} else {
		version = "v1"
		status, msg = check_api(params, float64(block_time))
	}

	log.Info("Status %s - %s (%d blocks): %s",
		 version, params.Url, block_time / 2, status)

	if status != haproxy.HealthCheckUp && len(msg) > 0 {
		log.Warning(msg)
	}

	// Report status to HAproxy
	c.Send(fmt.Sprintln(status))
	c.Close()
}

//  spawnTcpServer
// ---------------------------------------------------------

func spawnTcpServer(addr string) {

	server := tcp_server.New(addr)
	server.OnNewMessage(onTcpMessage);
    server.Listen()
}