API Gateway Part 3

blog20190228-01.cfg

backend apiservers
    balance roundrobin
    server server1 192.168.50.3:80 check

blog20190228-02.cfg

server server1 192.168.50.3:80 check inter 5s downinter 5s fall 3 rise 3

blog20190228-03.cfg

backend apiservers
    balance roundrobin
    option httpchk GET /check
    server server1 192.168.50.3:80 check

blog20190228-04.cfg

option httpchk GET /check
server server1 192.168.50.3:443 check  port 80

blog20190228-05.cfg

option httpchk GET /check HTTP/1.1\r\nHost:\ mywebsite.com
server server1 192.168.50.3:80 check  port 80

blog20190228-06.cfg

backend apiservers
   balance roundrobin
   option httpchk GET /check
   http-check expect status 200
   server server1 192.168.50.3:80 check

blog20190228-07.cfg

http-check expect string success

blog20190228-08.cfg

backend apiservers
    balance roundrobin
    option redispatch
    server server1 192.168.50.3:80 check inter 2m downinter 2m observe layer4 error-limit 10 on-error mark-down

blog20190228-09.sh

Server apiservers/server1 is DOWN, reason: Health analyze, info: "Detected 10 consecutive errors, last one was: L4 unsuccessful connection". 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.

blog20190228-10.sh

Server apiservers/server1 is UP, reason: Layer4 check passed, check duration: 0ms. 2 active and 0 backup servers online. 0 sessions requeued, 0 total in queue.

blog20190228-11.cfg

server server1 192.168.50.3:80 check inter 2m downinter 2m observe layer7 error-limit 10 on-error mark-down

blog20190228-12.cfg

backend apiservers
    balance roundrobin
    server server1 192.168.50.3:80 check weight 100 agent-check agent-inter 5s agent-addr 192.168.50.3 agent-port 9999

blog20190228-13.go

package main

import (
    "fmt"
    "time"
    "github.com/firstrow/tcp_server"
    "github.com/mackerelio/go-osstat/cpu"
)

func main() {
    server := tcp_server.New(":9999")

    server.OnNewClient(func(c *tcp_server.Client) {
        fmt.Println("Client connected")
        cpuIdle, err := getIdleTime()

        if err != nil {
            fmt.Println(err)
            c.Close()
            return
        }

        if cpuIdle < 10 {
            // Set server weight to half
            c.Send("50%\n")
        } else {
            c.Send("100%\n")
        }

        c.Close()
    })

    server.Listen()
}

func getIdleTime() (float64, error) {
    before, err := cpu.Get()
    if err != nil {
        return 0, err
    }
    time.Sleep(time.Duration(1) * time.Second)
    after, err := cpu.Get()
    if err != nil {
        return 0, err
    }
    total := float64(after.Total - before.Total)
    cpuIdle := float64(after.Idle-before.Idle) / total * 100
    return cpuIdle, nil
}

blog20190228-14.cfg

listen stats
    bind *:8404
    stats enable
    stats uri /
    stats refresh 5s

blog20190228-15.cfg

backend apiservers
    balance roundrobin
    server server1 192.168.50.3:80 check maxconn 30

blog20190228-16.cfg

backend apiservers
    balance leastconn
    timeout queue 5s
    server server1 192.168.50.3:80 check maxconn 30

blog20190228-17.cfg

frontend api_gateway_northamerica
    bind :80
    acl northamerica_toobusy avg_queue(northamerica) gt 20
    acl europe_up srv_is_up(europe/server1)
    use_backend europe if northamerica_toobusy europe_up
    default_backend northamerica
  
backend northamerica
    balance leastconn
    timeout queue 5s
    server server1 server1:80 check maxconn 30

backend europe
    option httpchk GET /check
    server server1 eu-api.mysite.com:80 check port 8080

blog20190228-18.cfg

frontend api_gateway_europe
    bind :80
    default_backend europe

frontend health_check
    bind :8080
    monitor-uri /check
    acl europe_toobusy avg_queue(europe) gt 20
    monitor fail if europe_toobusy

backend europe
    balance leastconn
    timeout queue 5s
    server server1 server1:80 check maxconn 30