Golang后端Docker容器API调用遇net::ERR_CONNECTION_REFUSED问题求助

前端报错信息 #

index-149c02ff.js:166 
        
       POST https://cihanbatasul.com:8081/register net::ERR_CONNECTION_REFUSED
st @ index-149c02ff.js:166
(anonymous) @ index-149c02ff.js:166
await in (anonymous) (async)
Nb @ index-149c02ff.js:37
Tb @ index-149c02ff.js:37
Ub @ index-149c02ff.js:37
nf @ index-149c02ff.js:37
se$2 @ index-149c02ff.js:37
(anonymous) @ index-149c02ff.js:37
Rk @ index-149c02ff.js:40
Jb @ index-149c02ff.js:37
hd @ index-149c02ff.js:37
fd @ index-149c02ff.js:37
ed @ index-149c02ff.js:37
index-149c02ff.js:166 TypeError: Failed to fetch
    at st (index-149c02ff.js:166:107788)
    at index-149c02ff.js:166:98541

后端main.go代码（已配置CORS） #

package main

import (
    "crypto/rand"
    "crypto/tls"
    "database/sql"
    "encoding/base64"
    "flag"
    "fmt"
    "log"
    "net/http"
    "os"

    "github.com/cihanbatasul/bookapi/internal/models"
    "github.com/joho/godotenv"
    _ "github.com/lib/pq"
    "github.com/rs/cors"
)

type application struct {
    error_log    *log.Logger
    info_log     *log.Logger
    books        *models.BookServiceImplementation
    users        *models.UserServiceImplementation
    user_helpers *models.UserHelperServiceImplementation
    ai           *models.AiServiceImplementation
}

func openDB(dsn string) (*sql.DB, error) {
    db, err := sql.Open("postgres", dsn)
    if err != nil {
        return nil, err
    }

    if err = db.Ping(); err != nil {
        return nil, err
    }

    return db, nil
}

func generateRandomSecret(length int) (string, error) {
    secretBytes := make([]byte, length)
    _, err := rand.Read(secretBytes)
    if err != nil {
        return "", err
    }
    return base64.StdEncoding.EncodeToString(secretBytes), nil
}

func main() {

    if err := godotenv.Load(".env"); err != nil {
        log.Fatalf("Fehler beim Laden der .env-Datei %v", err)
    }

    cors := cors.New(cors.Options{
        AllowedOrigins:   []string{"https://cihanbatasul.com", "http://localhost", "https://books.cihanbatasul.com"},
        AllowedMethods:   []string{"GET", "POST", "OPTIONS"},
        AllowedHeaders:   []string{"Content-Type"},
        AllowCredentials: true,
    })

    addr := flag.String("addr", ":8081", "HTTPS network address")
    flag.Parse()

    dsn := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable", os.Getenv("HOST"), os.Getenv("DB_PORT"), os.Getenv("USER_NAME"), os.Getenv("PASSWORD"), os.Getenv("DB_NAME"))

    info_log := log.New(os.Stdout, "INFO\t", log.Ldate|log.Ltime)
    error_log := log.New(os.Stderr, "ERROR\t", log.Ldate|log.Ltime|log.Lshortfile)

    db, err := openDB(dsn)
    if err != nil {
        fmt.Printf("%s", dsn)
        error_log.Fatal(err)
    }

    defer db.Close()

    app := &application{
        error_log:    error_log,
        info_log:     info_log,
        books:        &models.BookServiceImplementation{},
        users:        &models.UserServiceImplementation{DB: db},
        user_helpers: &models.UserHelperServiceImplementation{},
        ai:           &models.AiServiceImplementation{},
    }

    handler := cors.Handler(app.Routes())

    certPath := "certs/cert.pem"
    keyPath := "certs/privkey.pem"
    // Load TLS certificate and key
    cert, err := tls.LoadX509KeyPair(certPath, keyPath)
    if err != nil {
        log.Fatal("Error loading certificate and key:", err)
    }

    // Create TLS config
    tlsConfig := &tls.Config{
        Certificates: []tls.Certificate{cert},
    }

    // Create HTTPS server
    srv := &http.Server{
        Addr:      *addr,
        ErrorLog:  app.error_log,
        Handler:   handler,
        TLSConfig: tlsConfig,
    }

    info_log.Println("Starting server on port ", *addr)

    // Start HTTPS server
    err = srv.ListenAndServeTLS("", "")
    if err != nil {
        app.error_log.Fatal(err)
    }
}

容器状态 #

CONTAINER ID   IMAGE                  COMMAND                  CREATED          STATUS                     PORTS                                       NAMES
ca807a67f67a   booksbackend           "./main"                 14 minutes ago   Exited (1) 4 minutes ago                                               booksbackend_container
3516610db914   booksbackend_db        "docker-entrypoint.s…"   14 minutes ago   Up 14 minutes              0.0.0.0:5432->5432/tcp, :::5432->5432/tcp   booksbackend_db_container
6a2f27202298   portfolio2023:latest   "portfolio2023 -p 80…"   2 days ago       Up 2 days                  0.0.0.0:8080->8080/tcp, :::8080->8080/tcp   portfolio_backend

API容器Docker日志 #

intero@231:~$ sudo docker logs booksbackend_container
ERROR   2024/06/12 18:13:55 main.go:75: dial tcp 92.205.28.231:5432: connect: connection timed out

补充配置信息 #

.env环境变量 #

PORT=8081
DB_DOCKER_CONTAINER=booksbackend_db_container
DB_NAME=booksbackend_db
USER_NAME=intero
PASSWORD=thepassword
HOST=cihanbatasul.com
DB_PORT=5432
BINARY=bookapi

数据库Dockerfile #

FROM postgres:12-alpine

ENV POSTGRES_USER=intero
ENV POSTGRES_PASSWORD=thepassword
ENV POSTGRES_DB=booksbackend_db
EXPOSE 5432


COPY migrations/000001_books_migrations.up.sql /docker-entrypoint-initdb.d/init.sql

应用Dockerfile #

FROM golang:1.22.0-alpine3.19 AS builder

WORKDIR /app

COPY go.mod go.sum ./

RUN go mod download

COPY . .

RUN CGO_ENABLED=0 GOOS=linux go build -o main ./cmd/web

FROM alpine:latest

WORKDIR /app
COPY .env /app/

COPY --from=builder /app/main .

RUN mkdir -p certs
COPY certs/* certs/

EXPOSE 8081

CMD ["./main"]

解决步骤 #

1. 修改数据库连接地址：将.env中的HOST值从cihanbatasul.com改为数据库容器名booksbackend_db_container，Docker内部DNS会自动解析该名称到数据库容器的内部IP，避免通过公网IP连接超时。
2. 统一Docker网络：确保API容器和数据库容器处于同一Docker网络。若未创建自定义网络，执行docker network create books-net，启动两个容器时添加--network books-net参数。
3. 重新构建并启动容器：修改.env后，重新构建API镜像，再启动API容器和数据库容器，确保新配置生效。

内容的提问来源于stack exchange，提问作者intero