Add interpolation to JsonConfigurator

core/pom.xml

@@ -67,6 +67,10 @@
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-compress</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.commons</groupId>
+      <artifactId>commons-text</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.skife.config</groupId>
       <artifactId>config-magic</artifactId>
@@ -368,6 +372,11 @@
       <version>${postgresql.version}</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.github.stefanbirkner</groupId>
+      <artifactId>system-rules</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

core/src/main/java/org/apache/druid/guice/JsonConfigurator.java

@@ -27,10 +27,13 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
 import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.inject.Inject;
 import com.google.inject.ProvisionException;
 import com.google.inject.spi.Message;
+import org.apache.commons.text.StringSubstitutor;
+import org.apache.commons.text.lookup.StringLookupFactory;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.java.util.common.logger.Logger;
 
@@ -58,6 +61,15 @@ public class JsonConfigurator
 
   private final ObjectMapper jsonMapper;
   private final Validator validator;
+  private final StringSubstitutor stringSubstitutor = new StringSubstitutor(StringLookupFactory.INSTANCE.interpolatorStringLookup(
+      ImmutableMap.of(
+          StringLookupFactory.KEY_SYS, StringLookupFactory.INSTANCE.systemPropertyStringLookup(),
+          StringLookupFactory.KEY_ENV, StringLookupFactory.INSTANCE.environmentVariableStringLookup(),
+          StringLookupFactory.KEY_FILE, StringLookupFactory.INSTANCE.fileStringLookup()
+      ),
+      null,
+      false
+  )).setEnableSubstitutionInVariables(true).setEnableUndefinedVariableException(true);
 
   @Inject
   public JsonConfigurator(
@@ -89,7 +101,7 @@ public <T> T configurate(
     Map<String, Object> jsonMap = new HashMap<>();
     for (String prop : props.stringPropertyNames()) {
       if (prop.startsWith(propertyBase)) {
-        final String propValue = props.getProperty(prop);
+        final String propValue = stringSubstitutor.replace(props.getProperty(prop));
         Object value;
         try {
           // If it's a String Jackson wants it to be quoted, so check if it's not an object or array and quote.

core/src/test/java/org/apache/druid/guice/JsonConfiguratorTest.java

@@ -27,7 +27,10 @@
 import org.apache.druid.TestObjectMapper;
 import org.junit.Assert;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
+import org.junit.contrib.java.lang.system.RestoreSystemProperties;
 
 import javax.validation.ConstraintViolation;
 import javax.validation.Validator;
@@ -43,6 +46,12 @@ public class JsonConfiguratorTest
   private final ObjectMapper mapper = new TestObjectMapper();
   private final Properties properties = new Properties();
 
+  @Rule
+  public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties();
+
+  @Rule
+  public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
+
   @Before
   public void setUp()
   {
@@ -159,6 +168,71 @@ public void testPropertyWithDot()
     Assert.assertEquals("prop1", obj.prop1);
 
   }
+
+  @Test
+  public void testPropertyInterpolation()
+  {
+    System.setProperty("my.property", "value1");
+    List<String> list = ImmutableList.of("list", "of", "strings");
+    environmentVariables.set("MY_VAR", "value2");
+
+    final JsonConfigurator configurator = new JsonConfigurator(mapper, validator);
+    properties.setProperty(PROP_PREFIX + "prop1", "${sys:my.property}");
+    properties.setProperty(PROP_PREFIX + "prop1List", "${file:UTF-8:src/test/resources/list.json}");
+    properties.setProperty(PROP_PREFIX + "prop2.prop.2", "${env:MY_VAR}");
+    final MappableObject obj = configurator.configurate(properties, PROP_PREFIX, MappableObject.class);
+    Assert.assertEquals(System.getProperty("my.property"), obj.prop1);
+    Assert.assertEquals(list, obj.prop1List);
+    Assert.assertEquals("value2", obj.prop2);
+  }
+
+  @Test
+  public void testPropertyInterpolationInName()
+  {
+    System.setProperty("my.property", "value1");
+    List<String> list = ImmutableList.of("list", "of", "strings");
+    environmentVariables.set("MY_VAR", "value2");
+
+    environmentVariables.set("SYS_PROP", "my.property");
+    System.setProperty("json.path", "src/test/resources/list.json");
+    environmentVariables.set("PROP2_NAME", "MY_VAR");
+
+    final JsonConfigurator configurator = new JsonConfigurator(mapper, validator);
+    properties.setProperty(PROP_PREFIX + "prop1", "${sys:${env:SYS_PROP}}");
+    properties.setProperty(PROP_PREFIX + "prop1List", "${file:UTF-8:${sys:json.path}}");
+    properties.setProperty(PROP_PREFIX + "prop2.prop.2", "${env:${env:PROP2_NAME}}");
+    final MappableObject obj = configurator.configurate(properties, PROP_PREFIX, MappableObject.class);
+    Assert.assertEquals(System.getProperty("my.property"), obj.prop1);
+    Assert.assertEquals(list, obj.prop1List);
+    Assert.assertEquals("value2", obj.prop2);
+  }
+
+  @Test
+  public void testPropertyInterpolationFallback()
+  {
+    List<String> list = ImmutableList.of("list", "of", "strings");
+
+    final JsonConfigurator configurator = new JsonConfigurator(mapper, validator);
+    properties.setProperty(PROP_PREFIX + "prop1", "${sys:my.property:-value1}");
+    properties.setProperty(PROP_PREFIX + "prop1List", "${unknown:-[\"list\", \"of\", \"strings\"]}");
+    properties.setProperty(PROP_PREFIX + "prop2.prop.2", "${MY_VAR:-value2}");
+    final MappableObject obj = configurator.configurate(properties, PROP_PREFIX, MappableObject.class);
+    Assert.assertEquals("value1", obj.prop1);
+    Assert.assertEquals(list, obj.prop1List);
+    Assert.assertEquals("value2", obj.prop2);
+  }
+
+  @Test
+  public void testPropertyInterpolationUndefinedException()
+  {
+    final JsonConfigurator configurator = new JsonConfigurator(mapper, validator);
+    properties.setProperty(PROP_PREFIX + "prop1", "${sys:my.property}");
+
+    Assert.assertThrows(
+        IllegalArgumentException.class,
+        () -> configurator.configurate(properties, PROP_PREFIX, MappableObject.class)
+    );
+  }
 }
 
 class MappableObject

core/src/test/resources/list.json

@@ -0,0 +1,5 @@
+[
+  "list",
+  "of",
+  "strings"
+]

docs/configuration/index.md

@@ -61,6 +61,35 @@ The `jvm.config` files contain JVM flags such as heap sizing properties for each
 
 Common properties shared by all services are placed in `_common/common.runtime.properties`.
 
+## Configuration Interpolation
+
+Configuration values can be interpolated from System Properties, Environment Variables, or local files. Below is an example of how this can be used:
+
+```
+druid.metadata.storage.type=${env:METADATA_STORAGE_TYPE}
+druid.processing.tmpDir=${sys:java.io.tmpdir}
+druid.segmentCache.locations=${file:UTF-8:/config/segment-cache-def.json}
+```
+
+Interpolation is also recursive so you can do:
+
+```
+druid.segmentCache.locations=${file:UTF-8:${env:SEGMENT_DEF_LOCATION}}
+```
+
+If the property is not set an exception will be thrown on startup, but a default can be provided if desired. Setting a default value will not work with file interpolation as an exception will be thrown if the file does not exist.
+
+```
+druid.metadata.storage.type=${env:METADATA_STORAGE_TYPE:-mysql}
+druid.processing.tmpDir=${sys:java.io.tmpdir:-/tmp}
+```
+
+If you need to set a variable that is wrapped by `${...}` but do not want it to be interpolated you can escape it by adding another `$`. For example:
+
+```
+config.name=$${value}
+```
+
 ## Common Configurations
 
 The properties under this section are common configurations that should be shared across all Druid services in a cluster.

integration-tests-ex/cases/src/test/java/org/apache/druid/testsEx/config/Initializer.java

@@ -260,7 +260,6 @@ public Builder(String clusterName)
       // previously set in Maven.
       propertyEnvVarBinding("druid.test.config.dockerIp", "DOCKER_IP");
       propertyEnvVarBinding("druid.zk.service.host", "DOCKER_IP");
-      propertyEnvVarBinding("druid.test.config.hadoopDir", "HADOOP_DIR");
       property("druid.client.https.trustStorePath", "client_tls/truststore.jks");
       property("druid.client.https.trustStorePassword", "druid123");
       property("druid.client.https.keyStorePath", "client_tls/client.jks");

integration-tests/pom.xml

@@ -651,7 +651,6 @@
                                 -Duser.timezone=UTC
                                 -Dfile.encoding=UTF-8
                                 -Ddruid.test.config.dockerIp=${env.DOCKER_IP}
-                                -Ddruid.test.config.hadoopDir=${env.HADOOP_DIR}
                                 -Ddruid.test.config.extraDatasourceNameSuffix=${extra.datasource.name.suffix}
                                 -Ddruid.zk.service.host=${env.DOCKER_IP}
                                 -Ddruid.client.https.trustStorePath=client_tls/truststore.jks

licenses.yaml

@@ -668,13 +668,16 @@ name: Apache Commons Lang
 license_category: binary
 module: java-core
 license_name: Apache License version 2.0
-version: 3.8.1
+version: 3.12.0
 libraries:
   - org.apache.commons: commons-lang3
 notices:
   - commons-lang3: |
       Apache Commons Lang
-      Copyright 2001-2018 The Apache Software Foundation
+      Copyright 2001-2021 The Apache Software Foundation
+
+      This product includes software developed at
+      The Apache Software Foundation (https://www.apache.org/).
 
 ---
 
@@ -719,23 +722,17 @@ name: Apache Commons Text
 license_category: binary
 module: java-core
 license_name: Apache License version 2.0
-version: 1.3
+version: 1.9
 libraries:
   - org.apache.commons: commons-text
 notices:
   - commons-text: |
       Apache Commons Text
-      Copyright 2001-2018 The Apache Software Foundation
+      Copyright 2014-2020 The Apache Software Foundation
 
----
+      This product includes software developed at
+      The Apache Software Foundation (https://www.apache.org/).
 
-name: Apache Commons Text
-license_category: binary
-module: java-core
-license_name: Apache License version 2.0
-version: 1.4
-libraries:
-  - org.apache.commons: commons-text
 ---
 
 name: Airline

pom.xml

@@ -269,7 +269,12 @@
             <dependency>
                 <groupId>org.apache.commons</groupId>
                 <artifactId>commons-lang3</artifactId>
-                <version>3.8.1</version>
+                <version>3.12.0</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.commons</groupId>
+                <artifactId>commons-text</artifactId>
+                <version>1.9</version>
             </dependency>
             <dependency>
                 <groupId>com.amazonaws</groupId>

server/pom.xml

@@ -448,7 +448,6 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-text</artifactId>
-            <version>1.3</version>
             <scope>test</scope>
         </dependency>
     </dependencies>