First release

.gitignore

@@ -10,3 +10,8 @@
 
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
+
+# IDE
+.idea/
+pxc-checker
+config/test.conf

.goreleaser.yml

@@ -0,0 +1,24 @@
+# This is an example goreleaser.yaml file with some sane defaults.
+# Make sure to check the documentation at http://goreleaser.com
+builds:
+  - 
+    env:
+      - CGO_ENABLED=0
+    binary: pxc-checker
+archive:
+  replacements:
+    darwin: MacOS
+    linux: Linux
+    windows: Windows
+    386: i386
+    amd64: x86_64
+checksum:
+  name_template: 'checksums.txt'
+snapshot:
+  name_template: "{{ .Tag }}-next"
+changelog:
+  sort: asc
+  filters:
+    exclude:
+    - '^docs:'
+    - '^test:'

.travis.yml

@@ -0,0 +1,20 @@
+language: go
+go:
+- 1.9.x
+- tip
+
+os:
+- linux
+dist: trusty
+sudo: false
+
+matrix:
+  allow_failures:
+  - go: tip
+
+gobuild_args: -v
+
+script:
+  - cd "${TRAVIS_BUILD_DIR}"
+  - go get
+  - go build -o pxc-checker ./...

checker.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/valyala/fasthttp"
+	"strconv"
+	"time"
+)
+
+type ReasonCode int
+
+const (
+	reasonInternalError    ReasonCode = -1
+	reasonOk               ReasonCode = 0
+	reasonForceEnabled     ReasonCode = 1
+	reasonNodeNotAvailable ReasonCode = 2
+	reasonWSRepFailed      ReasonCode = 3
+	reasonCheckTimeout     ReasonCode = 4
+	reasonRWDisabled       ReasonCode = 5
+)
+
+type Response struct {
+	*NodeStatus
+	ReasonText string
+	ReasonCode ReasonCode
+}
+
+func checkerHandler(ctx *fasthttp.RequestCtx) {
+
+	response := Response{NodeStatus: status}
+	ctx.SetContentType("application/json")
+
+	if config.CheckForceEnable {
+		ctx.SetStatusCode(fasthttp.StatusOK)
+		response.ReasonText = "Force enabled"
+		response.ReasonCode = reasonForceEnabled
+	} else if !status.NodeAvailable {
+		ctx.SetStatusCode(fasthttp.StatusServiceUnavailable)
+		response.ReasonText = "Node is not available"
+		response.ReasonCode = reasonNodeNotAvailable
+	} else if (status.WSRepStatus != 4) && (status.WSRepStatus != 2) {
+		ctx.SetStatusCode(fasthttp.StatusServiceUnavailable)
+		response.ReasonText = "WSRep failed"
+		response.ReasonCode = reasonWSRepFailed
+	} else if float64(status.Timestamp)+float64(config.CheckFailTimeout)/1000 < float64(time.Now().Unix()) {
+		ctx.SetStatusCode(fasthttp.StatusServiceUnavailable)
+		response.ReasonText = "Check timeout"
+		response.ReasonCode = reasonCheckTimeout
+	} else if !config.CheckROEnabled && !status.RWEnabled {
+		ctx.SetStatusCode(fasthttp.StatusServiceUnavailable)
+		response.ReasonText = "Node is read only"
+		response.ReasonCode = reasonRWDisabled
+	} else {
+		ctx.SetStatusCode(fasthttp.StatusOK)
+		response.ReasonText = "OK"
+		response.ReasonCode = reasonOk
+	}
+
+	if respJson, err := json.Marshal(response); err != nil {
+		errStr := fmt.Sprintf(`{"ReasonText":"Internal checker error","ReasonCode":%d,"err":"%s"}`, reasonInternalError, err)
+		ctx.SetBody([]byte(errStr))
+		ctx.SetStatusCode(fasthttp.StatusInternalServerError)
+	} else {
+		ctx.SetBody(respJson)
+	}
+
+	return
+}
+
+func checker(status *NodeStatus) {
+	for {
+		time.Sleep(time.Duration(config.CheckInterval) * time.Millisecond)
+		curStatus := &NodeStatus{}
+		curStatus.Timestamp = int(time.Now().Unix())
+
+		rows, err := dbConn.Query("SHOW GLOBAL VARIABLES;")
+		if err != nil {
+			*status = *curStatus
+			continue
+		}
+		curStatus.NodeAvailable = true
+
+		for rows.Next() {
+			var key, value string
+			err := rows.Scan(&key, &value)
+			if err != nil {
+				*status = *curStatus
+				continue
+			}
+			switch key {
+			case "read_only":
+				if value == "OFF" {
+					curStatus.RWEnabled = true
+				}
+			case "wsrep_local_state":
+				curStatus.WSRepStatus, _ = strconv.Atoi(value)
+			}
+		}
+
+		*status = *curStatus
+	}
+}

config/example.conf

@@ -0,0 +1,11 @@
+WEB_LISTEN=":9200"
+
+MYSQL_HOST="127.0.0.1"
+MYSQL_PORT=3306
+MYSQL_USER="monitor"
+MYSQL_PASS="monitorUserPassword"
+
+CHECK_RO_ENABLED=false
+CHECK_FORCE_ENABLE=false
+CHECK_INTERVAL=500 # ms
+CHECK_FAIL_TIMEOUT=3000 # ms

main.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"github.com/buaazp/fasthttprouter"
+	"github.com/labstack/gommon/log"
+	"github.com/namsral/flag"
+	"github.com/valyala/fasthttp"
+	"time"
+)
+
+type NodeStatus struct {
+	WSRepStatus   int
+	RWEnabled     bool
+	NodeAvailable bool
+	Timestamp     int
+}
+
+type Config struct {
+	WebListen        string
+	WebReadTimeout   int
+	WebWriteTimeout  int
+	CheckROEnabled   bool
+	CheckInterval    int
+	CheckFailTimeout int
+	CheckForceEnable bool
+	MysqlHost        string
+	MysqlPort        int
+	MysqlUser        string
+	MysqlPass        string
+	MysqlTimeout     int
+}
+
+var (
+	status = &NodeStatus{}
+	config *Config
+	dbConn *sql.DB
+)
+
+func main() {
+	var err error
+	config, err = parseFlags()
+	if err != nil {
+		log.Fatalf("Options parsing failed with err: %s", err)
+	}
+	dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/", config.MysqlUser, config.MysqlPass, config.MysqlHost, config.MysqlPort)
+	log.Printf("Connecting to mysql with dsn: %s", dsn)
+	dbConn, _ = sql.Open("mysql", dsn)
+
+	go checker(status)
+
+	router := getRouter()
+	server := &fasthttp.Server{
+		Handler:          router.Handler,
+		DisableKeepalive: true,
+		GetOnly:          true,
+		Concurrency:      2048,
+		ReadTimeout:      time.Duration(config.WebReadTimeout) * time.Millisecond,
+		WriteTimeout:     time.Duration(config.WebWriteTimeout) * time.Millisecond,
+	}
+
+	log.Printf("Server starting on %s", config.WebListen)
+	if err := server.ListenAndServe(config.WebListen); err != nil {
+		log.Fatalf("Error in ListenAndServe: %s", err)
+	}
+}
+
+func getRouter() *fasthttprouter.Router {
+	router := fasthttprouter.New()
+	router.GET("/", checkerHandler)
+	return router
+}
+
+func parseFlags() (*Config, error) {
+	config := Config{}
+	flag.StringVar(&config.WebListen, "WEB_LISTEN", ":9200", "Listen interface and port")
+	flag.IntVar(&config.WebReadTimeout, "WEB_READ_TIMEOUT", 30000, "Request read timeout, ms")
+	flag.IntVar(&config.WebWriteTimeout, "WEB_WRITE_TIMEOUT", 30000, "Request write timeout, ms")
+	flag.BoolVar(&config.CheckROEnabled, "CHECK_RO_ENABLED", false, "Make 'read_only' nodes availible")
+	flag.BoolVar(&config.CheckForceEnable, "CHECK_FORCE_ENABLE", false, "Ignoring checks status and force enable node")
+	flag.IntVar(&config.CheckInterval, "CHECK_INTERVAL", 500, "Mysql checks interval, ms")
+	flag.IntVar(&config.CheckFailTimeout, "CHECK_FAIL_TIMEOUT", 3000, "To count a node inaccessible if for the specified time there were no successful checks, ms")
+	flag.StringVar(&config.MysqlHost, "MYSQL_HOST", "127.0.0.1", "MySQL host addr")
+	flag.IntVar(&config.MysqlPort, "MYSQL_PORT", 3306, "MySQL port addr")
+	flag.StringVar(&config.MysqlUser, "MYSQL_USER", "monitor", "MySQL username")
+	flag.StringVar(&config.MysqlPass, "MYSQL_PASS", "", "MySQL password")
+
+	flag.Parse()
+	return &config, nil
+}

systemd/pxc-check@.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=PXC Checker
+After=network.target
+
+[Service]
+EnvironmentFile=/etc/pxc/checker/%i.conf
+ExecStart=/usr/bin/pxc-checker
+KillMode=process
+User=mysql
+Group=mysql
+
+[Install]
+WantedBy=multi-user.target