Implement EnvironmentVariablePasswordProvider (#3329)

* Implement EnvironmentVariablePasswordProvider

* Review Comment : rename passwordKey to passwordVariable

* add docs

* improve doc layout

* review comment: rename property for variable

common/src/main/java/io/druid/metadata/EnvironmentVariablePasswordProvider.java

@@ -0,0 +1,81 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.metadata;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.base.Preconditions;
+
+public class EnvironmentVariablePasswordProvider implements PasswordProvider
+{
+  private final String variable;
+
+  @JsonCreator
+  public EnvironmentVariablePasswordProvider(
+      @JsonProperty("variable") String variable
+  )
+  {
+    this.variable = Preconditions.checkNotNull(variable);
+  }
+
+  @JsonProperty("variable")
+  public String getVariable()
+  {
+    return variable;
+  }
+
+  @JsonIgnore
+  @Override
+  public String getPassword()
+  {
+    return System.getenv(variable);
+  }
+
+  @Override
+  public String toString()
+  {
+    return "EnvironmentVariablePasswordProvider{" +
+           "variable='" + variable + '\'' +
+           '}';
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    EnvironmentVariablePasswordProvider that = (EnvironmentVariablePasswordProvider) o;
+
+    return variable != null ? variable.equals(that.variable) : that.variable == null;
+
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return variable != null ? variable.hashCode() : 0;
+  }
+}

common/src/main/java/io/druid/metadata/PasswordProvider.java

@@ -26,9 +26,11 @@ import com.fasterxml.jackson.annotation.JsonTypeInfo;
 /**
  * Implement this for different ways to (optionally securely) access db passwords.
  */
-@JsonTypeInfo(use= JsonTypeInfo.Id.NAME, property="type", defaultImpl = DefaultPasswordProvider.class)
-@JsonSubTypes(value={
-    @JsonSubTypes.Type(name="default", value=DefaultPasswordProvider.class),
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type", defaultImpl = DefaultPasswordProvider.class)
+@JsonSubTypes(value = {
+    @JsonSubTypes.Type(name = "default", value = DefaultPasswordProvider.class),
+    @JsonSubTypes.Type(name = "environment", value = EnvironmentVariablePasswordProvider.class),
+
 })
 public interface PasswordProvider
 {

common/src/test/java/io/druid/metadata/EnvironmentVariablePasswordProviderTest.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.metadata;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+
+public class EnvironmentVariablePasswordProviderTest
+{
+  private static final ObjectMapper jsonMapper = new ObjectMapper();
+
+  @Test
+  public void testSerde() throws IOException
+  {
+    String providerString = "{\"type\": \"environment\", \"variable\" : \"test\"}";
+    PasswordProvider provider = jsonMapper.readValue(providerString, PasswordProvider.class);
+    Assert.assertTrue(provider instanceof EnvironmentVariablePasswordProvider);
+    Assert.assertEquals("test", ((EnvironmentVariablePasswordProvider) provider).getVariable());
+    PasswordProvider serde = jsonMapper.readValue(jsonMapper.writeValueAsString(provider), PasswordProvider.class);
+    Assert.assertEquals(provider, serde);
+  }
+}

docs/content/configuration/index.md

@@ -198,7 +198,7 @@ These properties specify the jdbc connection and other configuration around the
 |`druid.metadata.storage.type`|The type of metadata storage to use. Choose from "mysql", "postgresql", or "derby".|derby|
 |`druid.metadata.storage.connector.connectURI`|The jdbc uri for the database to connect to|none|
 |`druid.metadata.storage.connector.user`|The username to connect with.|none|
-|`druid.metadata.storage.connector.password`|The password to connect with.|none|
+|`druid.metadata.storage.connector.password`|The password provider or String password used to connect with.|none|
 |`druid.metadata.storage.connector.createTables`|If Druid requires a table and it doesn't exist, create it?|true|
 |`druid.metadata.storage.tables.base`|The base name for tables.|druid|
 |`druid.metadata.storage.tables.segments`|The table to use to look for segments.|druid_segments|
@@ -210,6 +210,26 @@ These properties specify the jdbc connection and other configuration around the
 |`druid.metadata.storage.tables.supervisors`|Used by the indexing service to store supervisor configurations.|druid_supervisors|
 |`druid.metadata.storage.tables.audit`|The table to use for audit history of configuration changes e.g. Coordinator rules.|druid_audit|
 
+#### Password Provider
+ 
+Environment variable password provider provides password by looking at specified environment variable. Use this in order to avoid specifying password in runtime.properties file.
+e.g 
+
+```json
+{ 
+    "type": "environment",
+    "variable": "METADATA_STORAGE_PASSWORD"   
+}
+```
+
+The values are described below. 
+
+|Field|Type|Description|Required|
+|-----|----|-----------|--------|
+|`type`|String|password provider type|Yes: `environment`|
+|`variable`|String|environment variable to read password from|Yes|
+
+
 ### Deep Storage
 
 The configurations concern how to push and pull [Segments](../design/segments.html) from deep storage.