在Cloud Build中运行Docker镜像时PostgreSQL连接被拒绝

错误信息 #

psql: error: connection to server at "localhost" (127.0.0.1), port 5432 failed: Connection refused
Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (::1), port 5432 failed: Cannot assign requested address
Is the server running on that host and accepting TCP/IP connections?

环境配置 #

基础镜像Dockerfile (postgresql_utils_unit_test_python3.9) #

FROM python:3.9-slim

# install docker from https://docs.docker.com/engine/install/debian/
# required for postrgresql-utils unit testing
RUN apt update -qq && \
    apt install -y -qq postgresql libpq-dev python3-dev gcc ca-certificates curl gnupg lsb-release && \
    mkdir -m 0755 -p /etc/apt/keyrings && \
    curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg && \
    echo \
        "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian $(lsb_release -cs) stable" \
        | tee /etc/apt/sources.list.d/docker.list > /dev/null

RUN apt update -qq && \
    apt install -y -qq docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Cloud Build配置 #

steps:
  - id: test and build 3.9
    name: postgresql_utils_unit_test_python3.9
    script: |
      #!/bin/bash
      docker pull postgres
      docker run --detach --name pgsql-dev -e POSTGRES_PASSWORD=test1234 -e POSTGRES_DB=control_manager -p 3205:5432 postgres
      pip install .
      pip install -r tests/requirements.txt
      python -m pytest tests

PostgreSQL连接代码 #

connection = "user=postgres password=test1234 host=localhost port=3205 dbname=control_manager"
db = connect(connection)

已尝试操作 #

• 通过docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <Container ID>获取容器IP替换localhost，连接失败
• 容器运行状态正常，docker container ls输出：

CONTAINER ID   IMAGE                                                                                                        COMMAND                  CREATED          STATUS                  PORTS                                       NAMES
d1247ce4db4c   postgres                                                                                                     "docker-entrypoint.s…"   2 seconds ago    Up Less than a second   0.0.0.0:3205->5432/tcp, :::3205->5432/tcp   pgsql-dev

• 容器内hosts文件：

127.0.0.1   localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.17.0.3  d1247ce4db4c

1. 等待PostgreSQL服务就绪 #

Docker启动Postgres容器后，服务需要几秒初始化时间，直接运行测试会因服务未就绪导致连接失败。在docker run后添加等待逻辑：

# 等待Postgres服务可用
until docker exec pgsql-dev pg_isready -U postgres; do
  echo "等待PostgreSQL启动..."
  sleep 2
done

将这段代码插入到Cloud Build脚本的docker run之后，pip install之前。

2. 修正网络连接方式 #

在Cloud Build的Docker-in-Docker环境中，localhost指向的是运行测试的容器，而非Postgres容器，有两种修正方式：

方式一：用容器名直接连接 #

修改Python连接字符串，把host=localhost改成host=pgsql-dev，端口用容器内部的5432（无需端口映射，可去掉-p 3205:5432）：

connection = "user=postgres password=test1234 host=pgsql-dev port=5432 dbname=control_manager"
db = connect(connection)

方式二：用Docker主机IP连接 #

Docker-in-Docker环境中，Docker主机的IP通常是172.17.0.1，用这个IP替换localhost，端口用映射的3205：

connection = "user=postgres password=test1234 host=172.17.0.1 port=3205 dbname=control_manager"
db = connect(connection)

3. 确保PostgreSQL允许外部连接 #

测试环境下，可在启动容器时添加POSTGRES_HOST_AUTH_METHOD=trust参数，避免连接权限问题：

docker run --detach --name pgsql-dev -e POSTGRES_PASSWORD=test1234 -e POSTGRES_DB=control_manager -e POSTGRES_HOST_AUTH_METHOD=trust postgres

内容的提问来源于stack exchange，提问作者Sean Conkie