Write active_conn connections counter

.circleci/config.yml

@@ -0,0 +1,34 @@
+version: 2.0
+jobs:
+  build:
+    docker:
+      - image: circleci/golang:1.12
+    steps:
+      - checkout
+      - run: ./build.sh
+  deploy:
+    docker:
+      - image: circleci/golang:1.14
+    steps:
+      - checkout
+      - run: |
+          mkdir dist/
+          go get github.com/mitchellh/gox
+          go get github.com/tcnksm/ghr
+          gox -output="dist/{{.Dir}}_{{.OS}}_{{.Arch}}" -os="linux darwin" -arch="386 amd64" ./paperlog
+          gox -output="dist/{{.Dir}}_{{.OS}}_{{.Arch}}" -os="linux windows darwin" -arch="386 amd64" ./slack
+          gox -output="dist/{{.Dir}}_{{.OS}}_{{.Arch}}" -os="linux windows darwin" -arch="386 amd64" ./get_secret
+          gox -output="dist/{{.Dir}}_{{.OS}}_{{.Arch}}" -os="linux windows darwin" -arch="386 amd64" ./active_conn
+          ghr -t ${GITHUB_TOKEN} -u ${CIRCLE_PROJECT_USERNAME} -r ${CIRCLE_PROJECT_REPONAME} -c ${CIRCLE_SHA1} -delete ${CIRCLE_TAG} ./dist/
+
+workflows:
+  version: 2
+  release:
+    jobs:
+      - build
+      - deploy:
+          filters:
+            tags:
+              only: /v[0-9]+(\.[0-9]+)*(-.*)*/
+            branches:
+              ignore: /.*/

.gitignore

@@ -1,3 +1,4 @@
 *.exe
 dist/
-*.log
+*.log
+.env

README.md

@@ -6,6 +6,7 @@ A suite CLI tools & utilities
 - [slack](./slack) - send slack notifications
 - [get_secret](./get_secret) - fetch AWS Secrets Manager Secrets
 - [dumb_daemon](./dumb_daemon) - A useless daemon that just appends to a log file
+- [active_conn](./active_conn) - Print number of active Mysql connections every x seconds
 
 ## Basic Usage
 

active_conn/.env.sample

@@ -0,0 +1,4 @@
+DB_HOST=localhost
+DB_USER=
+DB_PASS=
+DB_NAME=

active_conn/.gitignore

@@ -0,0 +1 @@
+active_conn

active_conn/README.md

@@ -0,0 +1,8 @@
+# active_conn
+
+Prints the number of active MySQL connections to a database at a desired interval (default: 5seconds)
+
+```
+./active_conn -interval 10s
+```
+- Print number of active connections every 10 seconds

active_conn/go.mod

@@ -0,0 +1,8 @@
+module github.com/peteretelej/tools/active_conn
+
+go 1.14
+
+require (
+	github.com/go-sql-driver/mysql v1.5.0
+	github.com/joho/godotenv v1.3.0
+)

active_conn/go.sum

@@ -0,0 +1,4 @@
+github.com/go-sql-driver/mysql v1.5.0 h1:ozyZYNQW3x3HtqT1jira07DN2PArx2v7/mN66gGcHOs=
+github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
+github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
+github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=

active_conn/main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"database/sql"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/joho/godotenv"
+)
+
+var db *sql.DB
+
+func main() {
+	var (
+		interval = flag.Duration("interval", time.Second*5, "Interval between active connections checks")
+	)
+	flag.Parse()
+	log.SetPrefix("[active_conn] ")
+	if _, err := os.Stat(".env"); err == nil {
+		err := godotenv.Load()
+		if err != nil {
+			log.Fatal("Error loading .env file")
+		}
+	}
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	go func() {
+		select {
+		case _ = <-c:
+			log.Printf("Shutting down..")
+			if err := cleanup(); err != nil {
+				log.Fatalf("cleanup failed: %v", err)
+			}
+			os.Exit(0)
+		}
+	}()
+	if err := dbconn(); err != nil {
+		log.Fatalf("failed to connect to db: %v", err)
+	}
+
+	if err := checks(*interval); err != nil {
+		log.Printf("checks failed: %v", err)
+		if err := cleanup(); err != nil {
+			log.Fatal(err)
+		}
+	}
+}
+
+func dbconn() error {
+	for _, env := range []string{"DB_HOST", "DB_USER", "DB_PASS"} {
+		if v := os.Getenv(env); v == "" {
+			return fmt.Errorf("Missing environment variable: %s (please see .env.sample)", env)
+		}
+	}
+	var err error
+	db, err = sql.Open("mysql",
+		fmt.Sprintf("%s:%s@tcp(%s:3306)/%s",
+			os.Getenv("DB_USER"), os.Getenv("DB_PASS"),
+			os.Getenv("DB_HOST"), os.Getenv("DB_NAME")),
+	)
+	if err != nil {
+		return err
+	}
+	return db.Ping()
+}
+
+func cleanup() error {
+	if err := db.Close(); err != nil {
+		log.Printf("Failed to close db conn: %v", err)
+	}
+	return nil
+}
+
+func countConns() (int, error) {
+	var count int
+	var a string
+	err := db.QueryRow("show status where `variable_name` = 'Threads_connected' ").Scan(&a, &count)
+	if err != nil {
+		return 0, err
+	}
+	return count, nil
+
+}
+
+func checks(interval time.Duration) error {
+	if interval < time.Second {
+		return fmt.Errorf("interval can't be less than 1 second")
+	}
+	for {
+		c, err := countConns()
+		if err != nil {
+			return err
+		}
+		log.Printf("DB connections: %d", c)
+		time.Sleep(interval)
+	}
+}

build.sh

@@ -3,7 +3,7 @@ set -e
 
 echo "Vetting, testing & building all Go binaries"
 
-names=(paperlog get_secret slack)
+names=(paperlog get_secret slack active_conn)
 
 for n in "${names[@]}"
 do