feat: init

.env.example

@@ -0,0 +1 @@
+SERVICE_URI=postgresql://localhost:5432/postgres

.gitignore

@@ -1,3 +1,8 @@
+.idea
+ca.pem
+
+
+
 # If you prefer the allow list template instead of the deny list, see community template:
 # https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
 #

Dockerfile

@@ -0,0 +1,45 @@
+ARG GO_VERSION=1.24.10
+FROM --platform=$BUILDPLATFORM golang:${GO_VERSION} AS build
+WORKDIR /src
+
+RUN --mount=type=cache,target=/go/pkg/mod/ \
+    --mount=type=bind,source=go.sum,target=go.sum \
+    --mount=type=bind,source=go.mod,target=go.mod \
+    go mod download -x
+
+ARG TARGETARCH
+
+RUN --mount=type=cache,target=/go/pkg/mod/ \
+    --mount=type=bind,target=. \
+    CGO_ENABLED=0 GOARCH=$TARGETARCH go build -o /bin/server .
+
+FROM alpine:latest AS final
+
+RUN --mount=type=cache,target=/var/cache/apk \
+    apk --update add \
+        ca-certificates \
+        tzdata \
+        && \
+        update-ca-certificates
+
+ARG UID=10001
+RUN adduser \
+    --disabled-password \
+    --gecos "" \
+    --home "/nonexistent" \
+    --shell "/sbin/nologin" \
+    --no-create-home \
+    --uid "${UID}" \
+    appuser
+
+RUN mkdir -p /app && chown -R appuser:appuser /app
+
+USER appuser
+
+COPY --from=build /bin/server /bin/
+
+WORKDIR /app
+
+EXPOSE 1999
+
+ENTRYPOINT [ "/bin/server" ]

go.mod

@@ -0,0 +1,10 @@
+module github.com/tiennm99/postgresql-keepalive
+
+go 1.23.12
+
+toolchain go1.24.10
+
+require (
+	github.com/joho/godotenv v1.5.1
+	github.com/lib/pq v1.10.9
+)

go.sum

@@ -0,0 +1,4 @@
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=

init.sql

@@ -0,0 +1,33 @@
+-- Drop and recreate the database
+DROP DATABASE IF EXISTS keepalive;
+CREATE DATABASE keepalive;
+
+-- Create user if not exists
+DO
+$do$
+BEGIN
+   IF NOT EXISTS (
+       SELECT FROM pg_catalog.pg_roles WHERE rolname = 'keepalive'
+   ) THEN
+CREATE ROLE keepalive LOGIN PASSWORD 'keepalive';
+END IF;
+END
+$do$;
+
+-- Grant full permissions on this database
+GRANT ALL PRIVILEGES ON DATABASE keepalive TO keepalive;
+
+-- Connect to the database
+\c keepalive;
+
+-- Create the table for key/value counters
+CREATE TABLE IF NOT EXISTS keepalive (
+                                         key VARCHAR(255) PRIMARY KEY,
+    value BIGINT NOT NULL
+    );
+
+-- Initialize key/value
+INSERT INTO keepalive (key, value)
+VALUES ('counter', 0)
+    ON CONFLICT (key) DO UPDATE
+                             SET value = EXCLUDED.value;

main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"log"
+	"net/url"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/joho/godotenv"
+	_ "github.com/lib/pq"
+)
+
+func main() {
+	if err := godotenv.Load(); err != nil {
+		log.Println("Warning: .env file not found")
+	}
+
+	serviceURI, isExist := os.LookupEnv("SERVICE_URI")
+	if !isExist {
+		log.Fatal("Warning: SERVICE_URI not set!")
+		return
+	}
+	conn, _ := url.Parse(serviceURI)
+	conn.RawQuery = "sslmode=verify-ca;sslrootcert=ca.pem"
+
+	db, err := sql.Open("postgres", conn.String())
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	go func() {
+		ticker := time.NewTicker(time.Minute)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ticker.C:
+				if err := incrementCounter(ctx, db); err != nil {
+					log.Printf("Keepalive increment error: %v", err)
+				}
+			case <-ctx.Done():
+				return
+			}
+		}
+	}()
+
+	defer func() {
+		cancel()
+		if err := db.Close(); err != nil {
+			log.Printf("Close error: %v", err)
+			return
+		}
+	}()
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	<-sigCh
+}
+
+func incrementCounter(ctx context.Context, db *sql.DB) error {
+	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
+	defer cancel()
+
+	tx, err := db.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelReadCommitted})
+	if err != nil {
+		return err
+	}
+
+	var value int64
+	err = tx.QueryRowContext(ctx,
+		"UPDATE keepalive SET value = value + 1 WHERE key = 'counter' RETURNING value",
+	).Scan(&value)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return err
+	}
+
+	log.Printf("Counter: %d\n", value)
+	return nil
+}