Docker 撰写 (v2) UnknownHostException

Question

我在使用 Docker Compose 并尝试 link 一个带有 mysql 容器的 spring 引导 Web 应用程序容器时得到一个 "java.net.UnkownHostException: mysql: unknown error"。

docker-compose.yml更新#1

version: '2'

services:
web:
depends_on:
- db
image: thomptr/rest-services-ui:latest
ports:
- "9000:9000"
links:
- "db:database"
restart: always
environment:
SPRING_PROFILES_ACTIVE: dev
envTarget: dev

db:
image: mysql:5.7
ports:
- "3307:3306"
volumes:
- "/home/trevor/softwareDev/mySql/dump:/docker-entrypoint-initdb.d"
environment:
MYSQL_ROOT_PASSWORD: legion03
MYSQL_DATABASE: dev
MYSQL_USER: dbuser
MYSQL_PASSWORD: legion03

应用-dev.properties更新#1

spring.profiles.active=dev
server.contextPath=/restservices
server.port: 9000

spring.datasource.initialize=false
spring.datasource.platform=mysql
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://database:3306/dev

spring.datasource.username=dbuser
spring.datasource.password=legion03;
hibernate.level.logging=debug

spring.jpa.hibernate.ddl-auto=update
spring.jpa.hibernate.naming_strategy=org.hibernate.cfg.ImprovedNamingStrategy
spring.jpa.database=mysql
spring.jpa.show-sql=true
spring.jpa.generate-ddl=true
spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect

来自 /dockercompose_web_1 容器的日志

 2016-07-01 04:17:24.119 ERROR 1 --- [ost-startStop-1] o.a.tomcat.jdbc.pool.ConnectionPool      : Unable to create initial connections of pool.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
Caused by: java.net.UnknownHostException: mysql: unknown error
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)

更新 #2 Nguyen Sy Thanh Son 建议的方法是正确的。我的解决方案使用 public wait-for-it.sh 脚本。在这里查看我的解决方案：https://github.com/thomptr/DockerDemo

Answer 1

当 web 容器在 mysql 容器启动之前启动时，将发生此错误。

要解决此问题，我认为您应该将脚本添加到 entrypont.sh of web 图片中，如下所示

host="db"
password="$MYSQL_ROOT_PASSWORD" #mysql root password

until mysql -h "$host" -uroot -p$password; do
  >&2 echo "MYSQL is unavailable - sleeping"
  sleep 1
done

>&2 echo "MYSQL is up - executing command"

# start your app here

上面的脚本将等到 mysql 在运行应用程序

之前启动

您的应用程序 Dockerfile 应包含：

# run app
COPY entrypoint.sh /
RUN chmod +x /entrypoint.sh

ENTRYPOINT ["/entrypoint.sh"]

Answer 2

我认为这个错误是由于第一个容器不知道谁是数据库。从容器 A 到容器 B 的链接不会在两个容器中修改 /etc/hosts。

实现此目的的另一种方法是使用别名。你应该在这里找到你需要的所有信息

https://docs.docker.com/compose/compose-file/#aliases

并修改 spring 参数：

spring.datasource.url=jdbc:mysql://<whatever alias you choose for db>:3306/dev

如果这有效，请告诉我。

Docker 撰写 (v2) UnknownHostException

Docker compose (v2) UnkownHostException

spring

docker

docker-compose