Add support for Vault's database backend.

We now support Vault's database backend directly. MySQL and PostgreSQL configuration properties are deprecated now in favor of spring.cloud.vault.database. Cassandra and MongoDB backends remain active and default to their deprecated backends to support multi-database configuration of multiple, various database types.

spring.cloud.vault:
    database:
        enabled: true
        role: readonly

Original pull request: gh-170.
Related ticket: gh-169.

docs/src/main/asciidoc/spring-cloud-vault.adoc

@@ -634,6 +634,7 @@ mechanism to more easily roll keys.
 
 Spring Cloud Vault integrates with these backends:
 
+* <<vault.config.backends.database>>
 * <<vault.config.backends.cassandra>>
 * <<vault.config.backends.mongodb>>
 * <<vault.config.backends.mysql>>
@@ -644,8 +645,8 @@ backend in the configuration and the `spring-cloud-vault-config-databases`
 dependency.
 
 Vault ships since 0.7.1 with a dedicated `database` secret backend that allows
-database integration via plugins. You can use that specific backend by adapting
-one of the JDBC database properties above. Make sure to specify the appropriate
+database integration via plugins. You can use that specific backend by using the
+generic database backend. Make sure to specify the appropriate
 backend path, e.g. `spring.cloud.vault.mysql.role.backend=database`.
 
 .pom.xml
@@ -666,8 +667,48 @@ NOTE: Enabling multiple JDBC-compliant databases will generate credentials
 and store them by default in the same property keys hence property names for
 JDBC secrets need to be configured separately.
 
+[[vault.config.backends.database]]
+=== Database
+
+Spring Cloud Vault can obtain credentials for any Database listed at
+https://www.vaultproject.io/api/secret/databases/index.html.
+The integration can be enabled by setting
+`spring.cloud.vault.database.enabled=true` (default `false`) and
+providing the role name with `spring.cloud.vault.database.role=…`.
+
+Username and password are stored in `spring.datasource.username`
+and `spring.datasource.password` so using Spring Boot will
+pick up the generated credentials without further configuration.
+You can configure the property names by setting
+`spring.cloud.vault.database.username-property` and
+`spring.cloud.vault.database.password-property`.
+
+====
+[source,yaml]
+----
+spring.cloud.vault:
+    database:
+        enabled: true
+        role: readonly
+        backend: database
+        username-property: spring.datasource.username
+        password-property: spring.datasource.username
+----
+====
+
+* `enabled` setting this value to `true` enables the Database backend config usage
+* `role` sets the role name of the Database role definition
+* `backend` sets the path of the Database mount to use
+* `username-property` sets the property name in which the Database username is stored
+* `password-property` sets the property name in which the Database password is stored
+
+See also: https://www.vaultproject.io/docs/secrets/databases/index.html[Vault Documentation: Database Secrets backend]
+
+
 [[vault.config.backends.cassandra]]
 === Apache Cassandra
+This backend has been deprecated in Vault and it is recommended to use the `database` backend
+and mount it as `cassandra`.
 
 Spring Cloud Vault can obtain credentials for Apache Cassandra.
 The integration can be enabled by setting
@@ -705,6 +746,9 @@ See also: https://www.vaultproject.io/docs/secrets/cassandra/index.html[Vault Do
 [[vault.config.backends.mongodb]]
 === MongoDB
 
+This backend has been deprecated in Vault and it is recommended to use the `database` backend
+and mount it as `mongodb`.
+
 Spring Cloud Vault can obtain credentials for MongoDB.
 The integration can be enabled by setting
 `spring.cloud.vault.mongodb.enabled=true` (default `false`) and
@@ -740,6 +784,8 @@ See also: https://www.vaultproject.io/docs/secrets/mongodb/index.html[Vault Docu
 
 [[vault.config.backends.mysql]]
 === MySQL
+This backend has been deprecated in Vault and it is recommended to use the `database` backend
+and mount it as `mysql`.
 
 Spring Cloud Vault can obtain credentials for MySQL.
 The integration can be enabled by setting
@@ -776,6 +822,8 @@ See also: https://www.vaultproject.io/docs/secrets/mysql/index.html[Vault Docume
 
 [[vault.config.backends.postgresql]]
 === PostgreSQL
+This backend has been deprecated in Vault and it is recommended to use the `database` backend
+and mount it as `postgresql`.
 
 Spring Cloud Vault can obtain credentials for PostgreSQL.
 The integration can be enabled by setting

spring-cloud-vault-config-databases/src/main/java/org/springframework/cloud/vault/config/databases/VaultConfigDatabaseBootstrapConfiguration.java

@@ -38,7 +38,7 @@ import org.springframework.vault.core.util.PropertyTransformer;
 @Configuration
 @EnableConfigurationProperties({ VaultMySqlProperties.class,
 		VaultPostgreSqlProperties.class, VaultCassandraProperties.class,
-		VaultMongoProperties.class })
+		VaultMongoProperties.class, VaultDatabaseProperties.class })
 public class VaultConfigDatabaseBootstrapConfiguration {
 
 	@Bean

spring-cloud-vault-config-databases/src/main/java/org/springframework/cloud/vault/config/databases/VaultDatabaseProperties.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed 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 org.springframework.cloud.vault.config.databases;
+
+import lombok.Data;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.validation.annotation.Validated;
+
+import javax.validation.constraints.NotEmpty;
+
+/**
+ * Configuration properties for Vault using the Database integration.
+ *
+ * @author Per Abich
+ */
+@ConfigurationProperties("spring.cloud.vault.database")
+@Data
+@Validated
+public class VaultDatabaseProperties implements DatabaseSecretProperties {
+
+    /**
+     * Enable database backend usage.
+     */
+    private boolean enabled = false;
+
+    /**
+     * Role name for credentials.
+     */
+    private String role;
+
+    /**
+     * Database backend path.
+     */
+    @NotEmpty
+    private String backend = "database";
+
+    /**
+     * Target property for the obtained username.
+     */
+    @NotEmpty
+    private String usernameProperty = "spring.datasource.username";
+
+    /**
+     * Target property for the obtained password.
+     */
+    @NotEmpty
+    private String passwordProperty = "spring.datasource.password";
+}

spring-cloud-vault-config-databases/src/main/java/org/springframework/cloud/vault/config/databases/VaultPostgreSqlProperties.java

@@ -15,13 +15,12 @@
  */
 package org.springframework.cloud.vault.config.databases;
 
-import javax.validation.constraints.NotEmpty;
-
 import lombok.Data;
-
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.validation.annotation.Validated;
 
+import javax.validation.constraints.NotEmpty;
+
 /**
  * Configuration properties for Vault using the PostgreSQL integration.
  *