BAEL-2719: Spring Boot - Properties file outside jar

spring-boot-ops/src/main/java/com/baeldung/properties/ExternalPropertyFileLoader.java

@@ -0,0 +1,17 @@
+package com.baeldung.properties;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+
+@SpringBootApplication
+public class ExternalPropertyFileLoader {
+    public static void main(String[] args) {
+        ConfigurableApplicationContext applicationContext = new SpringApplicationBuilder(ExternalPropertyFileLoader.class).properties("spring.config.name:conf", "spring.config.location:file:src/main/resources/external/")
+            .build()
+            .run(args);
+        ConfigurableEnvironment environment = applicationContext.getEnvironment();
+        environment.getProperty("username");
+    }
+}

spring-boot-ops/src/main/resources/external/conf.properties

@@ -0,0 +1,4 @@
+url=jdbc:postgresql://localhost:5432/
+username=admin
+password=root
+spring.main.allow-bean-definition-overriding=true

spring-boot-ops/src/test/java/com/baeldung/properties/ExternalPropertyFileLoaderUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.properties;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+public class ExternalPropertyFileLoaderUnitTest {
+
+    @Test
+    public void whenExternalisedPropertiesLoaded_thenReadValues() {
+        ConfigurableApplicationContext applicationContext = new SpringApplicationBuilder(ExternalPropertyFileLoader.class).properties("spring.config.name:conf", "spring.config.location:file:src/main/resources/external/")
+            .build()
+            .run();
+        ConfigurableEnvironment environment = applicationContext.getEnvironment();
+        Assert.assertEquals(environment.getProperty("url"), "jdbc:postgresql://localhost:5432/");
+        Assert.assertEquals(environment.getProperty("username"), "admin");
+        Assert.assertEquals(environment.getProperty("password"), "root");
+    }
+
+}