Scala 中按环境的特定配置
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specific config by environment in Scala
提问by Daniel Cukier
What is a good way to set up a project in Scala which uses different configuration depending on environments.
在 Scala 中设置项目的好方法是什么，它根据环境使用不同的配置。
I need to specifically have different databases for development, testand productionenvironment (similar to what is done in Rails)
我需要专门有不同的数据库用于开发、测试和生产环境（类似于在 Rails 中所做的）
回答by ozeebee
Another strategy I'm using consists of using includes.
I usually store my DEV settings in the defaultapplication.conffile then I create a new conf file for other environments and include the default one.
我正在使用的另一个策略是使用includes。我通常将我的 DEV 设置存储在默认application.conf文件中，然后我为其他环境创建一个新的 conf 文件并包含默认文件。
Let's say my DEV conf application.conflooks like this:
假设我的 DEV confapplication.conf如下所示：
myapp {
server-address = "localhost"
server-port = 9000
some-other-setting = "cool !"
}
Then for the PROD, I could have another file called prod.conf:
然后对于 PROD，我可以有另一个名为的文件prod.conf：
include "application"
# override default (DEV) settings
myapp {
server-address = ${PROD_SERVER_HOSTNAME}
server-port = ${PROD_SERVER_PORT}
}
Note that I override onlythe settings that change in the PROD environment (some-other-settingis thus the same as in DEV).
请注意，我仅覆盖在 PROD 环境中更改的设置（some-other-setting因此与 DEV 中的设置相同）。
The config bootstrap code doesn't test anything
配置引导代码不测试任何东西
...
val conf = ConfigFactory.load()
...
To switch from the DEV to the PROD conf, simply pass a system property with the name of the config file to load:
要从 DEV 切换到 PROD conf，只需传递一个带有要加载的配置文件名称的系统属性：
java -Dconfig.resource=prod.conf ...
In DEV, no need to pass it since application.confwill be loaded by default.
在 DEV 中，不需要传递它，因为它application.conf会默认加载。
So here we're using Typesafe Config's default loading mechanism to achieve this.
所以在这里我们使用Typesafe Config的默认加载机制来实现这一点。
I've created a simple projectto demonstrate this technique. Feel free to clone and experiment.
我创建了一个简单的项目来演示这种技术。随意克隆和实验。
回答by Daniel Cukier
Use typesafe Config. Create a Config object like this:
使用类型安全配置。像这样创建一个 Config 对象：
import com.typesafe.config._
object Config {
val env = if (System.getenv("SCALA_ENV") == null) "development" else System.getenv("SCALA_ENV")
val conf = ConfigFactory.load()
def apply() = conf.getConfig(env)
}
Then create the application.conffile in src/main/resourcesfolder:
然后在application.conf文件src/main/resources夹中创建文件：
development {
your_app {
databaseUrl = "jdbc:mysql://localhost:3306/dev_db"
databaseUser = "xxxx"
databasePassword = "xxxx"
}
}
test {
your_app {
databaseUrl = "jdbc:mysql://localhost:3306/test_db"
databaseUser = "xxxxx"
databasePassword = "xxxx"
}
}
Now from anywhere in your application, you can access configuration:
现在，您可以从应用程序的任何位置访问配置：
Config().getString("your_app.databaseUrl")
Config().getString("your_app.databaseUrl")
If you have your environment set up (e.g. export SCALA_ENV=test) when you run your application, it will consider the right configuration section. The default is development
如果您export SCALA_ENV=test在运行应用程序时设置了环境（例如），它将考虑正确的配置部分。默认是开发
回答by DHa
I wasn't happy with how Daniel Cukiers solution did not allow defaults and overrides, so I changed it around to make full use of those.
我对 Daniel Cukiers 解决方案不允许默认值和覆盖的方式感到不满意，因此我对其进行了更改以充分利用这些。
The only configuration you have to do is set a ENVIRONMENT variable on the system (defaults to 'dev' if none is set)
您唯一需要做的配置是在系统上设置一个 ENVIRONMENT 变量（如果没有设置，则默认为“dev”）
(Java solution, compatible with Scala):
（Java解决方案，兼容Scala）：
import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;
public class MyCompanyConfig {
public final static Config base = ConfigFactory.load().getConfig("mycompany");
public final static String environment = System.getenv("ENVIRONMENT") == null ? "dev" : System.getenv("ENVIRONMENT");
/**
* Returns a subtree of the base configuration with environment settings applied.
*
* @param setting The subtree to return config for.
* @return A config with base in given setting, with environment modifications applied.
*/
public static Config load(String setting) {
Config config = base.getConfig(setting);
if (config.hasPath(environment)) {
return config.getConfig(environment).withFallback(config);
}
return config;
}
}
This allows a single reference.conf in a library looking like this:
这允许库中的单个 reference.conf 如下所示：
mycompany.module1 {
setting1 : "adefaultvalue"
url : "localhost"
test {
// will be used where ENVIRONMENT="test"
url : "test.mycompany.com"
}
prod {
// will be used where ENVIRONMENT="prod"
setting1 : "changethedefault"
url : "www.mycompany.com"
}
}
Usage:
用法：
Config conf = MyCompanyConfig.load("module1")
