#1922. Default values for environment variable for YAML.

redisson/src/main/java/org/redisson/config/EnvProvider.java

+package org.redisson.config;
+
+/**
+ * Adaptor for key value storage, a.k.a. Environment.
+ */
+@FunctionalInterface
+interface EnvProvider {
+    
+    /**
+     * Gets the value of the specified environment variable. An
+     * environment variable is a system-dependent external named
+     * value.
+     *
+     * @param name the name of the environment variable
+     * @return the string value of the variable, or <code>null</code>
+     * if the variable is not defined in the system environment
+     */
+    String get(String name);
+    
+}

redisson/src/main/java/org/redisson/config/SystemEnvProvider.java

+package org.redisson.config;
+
+/**
+ * Default implementation for environment values adaptor.
+ */
+public class SystemEnvProvider implements EnvProvider {
+    
+    /**
+     * @see System#getenv()
+     */
+    @Override
+    public String get(String name) {
+        return System.getenv(name);
+    }
+    
+}

redisson/src/test/java/org/redisson/config/ConfigSupportTest.java

+package org.redisson.config;
+
+import com.fasterxml.jackson.databind.exc.InvalidFormatException;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URI;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.*;
+
+public class ConfigSupportTest {
+    
+    @Test
+    public void testParsingLiteral() throws IOException {
+        SingleServerConfig config = mkConfig("127.0.0.1", new HashMap<String, String>() {{
+            put("REDIS_URI", "1.1.1.1");
+        }});
+        
+        assertEquals(URI.create("redis://127.0.0.1"), config.getAddress());
+    }
+    
+    @Test
+    public void testParsingEnv() throws IOException {
+        SingleServerConfig config = mkConfig("${REDIS_URI}", new HashMap<String, String>() {{
+            put("REDIS_URI", "1.1.1.1");
+        }});
+        
+        assertEquals(URI.create("redis://1.1.1.1"), config.getAddress());
+    }
+    
+    @Test(expected = InvalidFormatException.class)
+    public void testParsingEnv_envMissing() throws IOException {
+        mkConfig("${REDIS_URI}", new HashMap<>());
+    }
+    
+    @Test
+    public void testParsingDefault_envPresent() throws IOException {
+        SingleServerConfig config = mkConfig("${REDIS_URI:-10.0.0.1}", new HashMap<String, String>() {{
+            put("REDIS_URI", "11.0.0.1");
+        }});
+        
+        assertEquals(URI.create("redis://11.0.0.1"), config.getAddress());
+    }
+    
+    @Test
+    public void testParsingDefault_envMissing() throws IOException {
+        SingleServerConfig config = mkConfig("${REDIS_URI:-10.0.0.1}", new HashMap<>());
+        
+        assertEquals(URI.create("redis://10.0.0.1"), config.getAddress());
+    }
+    
+    private SingleServerConfig mkConfig(String authorityValue, Map<String, String> env) throws IOException {
+        String config = "singleServerConfig:\n  address: redis://" + authorityValue;
+        return new ConfigSupport(env::get).fromYAML(config, Config.class).getSingleServerConfig();
+    }
+    
+}