java - 在 dropwizard 中使用环境变量覆盖配置时出现问题

Question

MyWebConfiguration.java 具有以下代码，如放置向导所述

public void initialize(Bootstrap<MyWebConfiguration> bootstrap) {
    LOG.info("Initializing configuration");
    // Enable variable substitution with environment variables
    bootstrap.setConfigurationSourceProvider(
       new SubstitutingSourceProvider(
           bootstrap.getConfigurationSourceProvider(),
             new EnvironmentVariableSubstitutor(false)
       )
   );
}

dev-services.yaml 文件有

tokenSecret: ${TOKEN_SECRET}

但是当我运行应用程序并调试以检查我获得的 tokenSecret 值时，它在调试控制台中显示 tokenSecret = "${TOKEN_SECRET}"。

我尝试按以下方式更改 MyWebConfiguration.java:-

bootstrap.setConfigurationSourceProvider(
       new SubstitutingSourceProvider(
           bootstrap.getConfigurationSourceProvider(),
             new EnvironmentVariableSubstitutor(true)// changed false to true
       )
   );

但是现在当我尝试运行该程序时，它显示以下错误

Exception in thread "main" io.dropwizard.configuration.UndefinedEnvironmentVariableException: The environment variable 'TOKEN_SECRET' is not defined; could not substitute the expression '${TOKEN_SECRET}'.
    at io.dropwizard.configuration.EnvironmentVariableLookup.lookup(EnvironmentVariableLookup.java:41)
    at org.apache.commons.lang3.text.StrSubstitutor.resolveVariable(StrSubstitutor.java:726)
    at org.apache.commons.lang3.text.StrSubstitutor.substitute(StrSubstitutor.java:649)
    at org.apache.commons.lang3.text.StrSubstitutor.substitute(StrSubstitutor.java:563)
    at org.apache.commons.lang3.text.StrSubstitutor.replace(StrSubstitutor.java:305)
    at io.dropwizard.configuration.SubstitutingSourceProvider.open(SubstitutingSourceProvider.java:39)
    at io.dropwizard.configuration.YamlConfigurationFactory.build(YamlConfigurationFactory.java:80)
    at io.dropwizard.cli.ConfiguredCommand.parseConfiguration(ConfiguredCommand.java:124)
    at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:72)
    at io.dropwizard.cli.Cli.run(Cli.java:75)
    at io.dropwizard.Application.run(Application.java:79)

谁能告诉我哪里出了问题？

Answer 1

您的环境变量不会传播。不会自动从您的系统传播到您从中启动 DropWizard 的 IDE。

其次，当使用new EnvironmentVariableSubstitutor(false)(非严格)时，您需要提供默认值，即使它们应该为空:

tokenSecret: ${TOKEN_SECRET:-}

当缺失时，严格将抛出UndefinedEnvironmentVariableException，非严格将使用空字符串。