Use tile service binding credentials as default property values

Adds CfEnv as a dependency and uses CfEnv to get credentials
from a `p-dataflow` service binding to set the SCDF URI
property and Oauth2 client credentials properties.

Use CfEnv version specification from parent pom

Author: markpollack

spring-cloud-dataflow-composed-task-runner/pom.xml

@@ -35,6 +35,10 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-dataflow-rest-client</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>io.pivotal.cfenv</groupId>
+			<artifactId>java-cfenv</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.mockito</groupId>
 			<artifactId>mockito-core</artifactId>

spring-cloud-dataflow-composed-task-runner/src/main/java/org/springframework/cloud/dataflow/composedtaskrunner/support/CfServiceBindingPropertySourceInitializer.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2017-2020 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
+ *
+ *      https://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.dataflow.composedtaskrunner.support;
+
+import java.util.HashMap;
+
+import io.pivotal.cfenv.core.CfCredentials;
+import io.pivotal.cfenv.core.CfEnv;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
+import org.springframework.context.ApplicationListener;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.StandardEnvironment;
+
+/**
+ * If the composed task runner is running on Cloud Foundry and is bound to a service instance from SCDF for VMware
+ * Tanzu, use the values from the service binding credentials to configure the composed task runner.
+ *
+ * @author Mike Heath
+ */
+public class CfServiceBindingPropertySourceInitializer
+		implements ApplicationListener<ApplicationEnvironmentPreparedEvent> {
+
+	private static final Logger log = LoggerFactory.getLogger(CfServiceBindingPropertySourceInitializer.class);
+
+	public static final String PROPERTY_SOURCE_NAME = "p-dataflow";
+
+	@Override
+	public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
+		final CfEnv cfEnv = new CfEnv();
+		try {
+			final CfCredentials credentials = cfEnv.findCredentialsByLabel("p-dataflow");
+			final HashMap<String, Object> propertiesMap = new HashMap<>();
+			propertiesMap.put("dataflowServerUri", credentials.getString("dataflow-url"));
+			propertiesMap.put("oauth2ClientCredentialsClientId", credentials.getString("client-id"));
+			propertiesMap.put("oauth2ClientCredentialsClientSecret", credentials.getString("client-secret"));
+			propertiesMap.put("oauth2ClientCredentialsTokenUri", credentials.getString("access-token-url"));
+
+			final MapPropertySource propertySource = new MapPropertySource(PROPERTY_SOURCE_NAME, propertiesMap);
+			event.getEnvironment().getPropertySources()
+					.addAfter(StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, propertySource);
+		} catch (IllegalArgumentException e) {
+			log.debug("No 'p-dataflow' service binding found in VCAP_SERVICES");
+		}
+	}
+
+}

spring-cloud-dataflow-composed-task-runner/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.context.ApplicationListener=\
+org.springframework.cloud.dataflow.composedtaskrunner.support.CfServiceBindingPropertySourceInitializer