spring-boot - 错误 :docker Spring boot container : java. lang.IllegalArgumentException:无法解析值 'CASSANDRA_HOST' 中的占位符 "${CASSANDRA_HOST}"

Question

我在 docker 容器内运行一个 spring boot 应用程序，它通过 docker 网络(驱动桥)将另一个 Cassandra 容器链接起来。问题是我正在使用一个名为 CASSANDRA_HOST 的环境变量 linux保存 Cassandra 的容器 IP 和 spring boot could not resolve placeholder 'CASSANDRA_HOST' in value "${CASSANDRA_HOST}" .

环境变量在Spring Boot容器中创建成功。我测试了其他环境变量，有些有效，有些无效。所以，我不明白错误在哪里。

错误:

 Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'CASSANDRA_HOST' in value "${CASSANDRA_HOST}"
                at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:178)
                at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124)
                at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239)
                at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210)
                at org.springframework.core.env.AbstractPropertyResolver.resolveNestedPlaceholders(AbstractPropertyResolver.java:230)
                at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:88)
                at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:62)
                at org.springframework.core.env.AbstractEnvironment.getProperty(AbstractEnvironment.java:535)
                at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:137)
                at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:133)
                at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:85)
                at org.springframework.core.env.PropertySourcesPropertyResolver.getPropertyAsRawString(PropertySourcesPropertyResolver.java:74)
                at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:151)
                at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124)
                at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239)
                at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210)
                at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.lambda$processProperties$0(PropertySourcesPlaceholderConfigurer.java:175)
                at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:936)
                at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1321)
                at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300)
                at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640)
                at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)
                at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
                ... 59 more

在application.properties中，我将变量设置如下:

cassandra.contactpoints= ${CASSANDRA_HOST}

在CassandraCoonfig类中，我设置了@value来读取IP:

@Configuration 
public class CassandraConfig extends  AbstractCassandraConfiguration {

    @Value("${cassandra.contactpoints}")    
    private String contactPoints;

在 POM.XML 中，我使用了标签 < filtering > :

<resources>
    <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
    </resource>
</resources>

编辑:这是 spring 容器中所有环境变量的打印。 CASSANDRA_HOST 在第 14 行。

Answer 1

我使用以下命令解决了在 docker-compose.yml 中构建桥接的问题:

networks:
  net:
    driver: "bridge"

这是完整的docker-compose.yml:

version: '3'

services:
  ... (your code)
  networks: 
    - net

networks:
      net:
        driver: "bridge"

在容器中的 docker 镜像中有了这个网络，您可以检查网络并找到所需的 IP。然后用这个 IP 设置环境变量。

它在我的场景中解决了。