how to read System environment variable in Spring applicationContext

You are close :o) Spring 3.0 adds Spring Expression Language. You can use

<util:properties id="dbProperties" location="classpath:config_#{systemProperties['env']}/db.properties" /> 

Combined with java ... -Denv=QA should solve your problem.

Note also a comment by @yiling:

In order to access system environment variable, that is OS level variables as amoe commented, we can simply use "systemEnvironment" instead of "systemProperties" in that EL. Like #{systemEnvironment['ENV_VARIABLE_NAME']}

Nowadays you can put

@Autowired private Environment environment; 

in your @Component, @Bean, etc., and then access the properties through the Environment class:

environment.getProperty("myProp"); 

For a single property in a @Bean

@Value("${my.another.property:123}") // value after ':' is the default Integer property; 

Another way are the handy @ConfigurationProperties beans:

@ConfigurationProperties(prefix="my.properties.prefix") public class MyProperties { // value from my.properties.prefix.myProperty will be bound to this variable String myProperty; // and this will even throw a startup exception if the property is not found @javax.validation.constraints.NotNull String myRequiredProperty; //getters } @Component public class MyOtherBean { @Autowired MyProperties myProperties; } 

Note: Just remember to restart eclipse after setting a new environment variable

Yes, you can do <property name="defaultLocale" value="#{ systemProperties['user.region']}"/> for instance.

The variable systemProperties is predefined, see 6.4.1 XML based configuration.

In your bean definition, make sure to include "searchSystemEnvironment" and set it to "true". And if you're using it to build a path to a file, specify it as a file:/// url.

So for example, if you have a config file located in

/testapp/config/my.app.config.properties 

then set an environment variable like so:

MY_ENV_VAR_PATH=/testapp/config 

and your app can load the file using a bean definition like this:

e.g.

<bean class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer"> <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /> <property name="searchSystemEnvironment" value="true" /> <property name="searchContextAttributes" value="true" /> <property name="contextOverride" value="true" /> <property name="ignoreResourceNotFound" value="true" /> <property name="locations"> <list> <value>file:///${MY_ENV_VAR_PATH}/my.app.config.properties</value> </list> </property> </bean> 

Using Spring EL you can eis example write as follows

<bean id="myBean" class="path.to.my.BeanClass"> <!-- can be overridden with -Dtest.target.host=http://whatever.com --> <constructor-arg value="#{systemProperties['test.target.host'] ?: 'http://localhost:18888'}"/> </bean> 

For my use case, I needed to access just the system properties, but provide default values in case they are undefined.

This is how you do it:

<bean id="propertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /> <property name="searchSystemEnvironment" value="true" /> </bean> <bean id="myBean" class="path.to.my.BeanClass"> <!-- can be overridden with -Dtest.target.host=http://whatever.com --> <constructor-arg value="${test.target.host:http://localhost:18888}"/> </bean> 

Declare the property place holder as follows

<bean id="propertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /> <property name="locations"> <list> <value>file:///path.to.your.app.config.properties</value> </list> </property> </bean> 

Then lets say you want to read System.property("java.io.tmpdir") for your Tomcat bean or any bean then add following in your properties file:

tomcat.tmp.dir=${java.io.tmpdir} 

Updated version (2020).

Use System.getenv("ENV_VARIABLE")

This is how you do it:

<bean id="systemPrereqs" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean" scope="prototype"> <property name="targetObject" value="#{@systemProperties}" /> <property name="targetMethod" value="putAll" /> <property name="arguments"> <util:properties> <prop key="deployment.env">dev</prop> </util:properties> </property> </bean> 

But remember spring gets loaded first and then it will load this bean MethodInvokingFactoryBean. So if you are trying to use this for your test case then make sure that you use depends-on. For e.g. in this case

In case you are using it for your main class better to set this property using your pom.xml as

<systemProperty> <name>deployment.env</name> <value>dev</value> </systemProperty> 

You can mention your variable attributes in a property file and define environment specific property files like local.properties, production.propertied etc.

Now based on the environment, one of these property file can be read in one the listeners invoked at startup, like the ServletContextListener.

The property file will contain the the environment specific values for various keys.

Sample "local.propeties"

db.logsDataSource.url=jdbc:mysql://localhost:3306/logs db.logsDataSource.username=root db.logsDataSource.password=root db.dataSource.url=jdbc:mysql://localhost:3306/main db.dataSource.username=root db.dataSource.password=root 

Sample "production.properties"

db.logsDataSource.url=jdbc:mariadb://111.111.111.111:3306/logs db.logsDataSource.username=admin db.logsDataSource.password=xyzqer db.dataSource.url=jdbc:mysql://111.111.111.111:3306/carsinfo db.dataSource.username=admin db.dataSource.password=safasf@mn 

For using these properties file, you can make use of REsource as mentioned below

 PropertyPlaceholderConfigurer configurer = new PropertyPlaceholderConfigurer(); ResourceLoader resourceLoader = new DefaultResourceLoader(); Resource resource = resourceLoader.getResource("classpath:"+System.getenv("SERVER_TYPE")+"DB.properties"); configurer.setLocation(resource); configurer.postProcessBeanFactory(beanFactory); 

SERVER_TYPE can be defined as the environment variable with appropriate values for local and production environment.

With these changes the appplicationContext.xml will have the following changes

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="${db.dataSource.url}" /> <property name="username" value="${db.dataSource.username}" /> <property name="password" value="${db.dataSource.password}" /> 

Hope this helps .

Thanks to @Yiling. That was a hint.

<bean id="propertyConfigurer" class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer"> <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /> <property name="searchSystemEnvironment" value="true" /> <property name="locations"> <list> <value>file:#{systemEnvironment['FILE_PATH']}/first.properties</value> <value>file:#{systemEnvironment['FILE_PATH']}/second.properties</value> <value>file:#{systemEnvironment['FILE_PATH']}/third.properties</value> </list> </property> </bean> 

After this, you should have one environment variable named 'FILE_PATH'. Make sure you restart your terminal/IDE after creating that environment variable.

Amra solution helped me to get this right. In my case, each server picked up its own property file who name came from the system variable.

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations" value="classpath:/config/#{systemProperties['APPLICATION_PROPERTIES_FILE']}"/> </bean> 

After this, I had to add the property key via Spring JSTL expression e.g

class="org.springframework.security.oauth2.provider.token.store.JwtAccessTokenConverter"> <property name="signingKey" value="${oauth.signingkey}"/> <property name="jwtClaimsSetVerifier" ref="OauthClaimVerifier"/> </bean>