log4j-spring-cloud-config/log4j-spring-cloud-config-samples/log4j-spring-cloud-config-sample-application/src/main/java/org/apache/logging/log4j/spring/cloud/config/sample/controller/K8SController.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.logging.log4j.spring.cloud.config.sample.controller;

import java.nio.file.Paths;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.kubernetes.KubernetesClientBuilder;
import org.apache.logging.log4j.util.Strings;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.databind.ObjectMapper;

import io.fabric8.kubernetes.api.model.Pod;
import io.fabric8.kubernetes.client.Config;
import io.fabric8.kubernetes.client.KubernetesClient;

/**
 * Test class
 */
@RestController
public class K8SController {

    private static final Logger LOGGER = LogManager.getLogger(K8SController.class);
    private static final String HOSTNAME = "HOSTNAME";
    @Autowired
    private ObjectMapper objectMapper;

    @GetMapping("/k8s/pod")
    public ResponseEntity<Pod> getPod() {
        try {
            KubernetesClient client = new KubernetesClientBuilder().createClient();
            if (client != null) {
                Pod pod = getCurrentPod(client);
                if (pod != null) {
                    LOGGER.info("Pod: {}", objectMapper.writeValueAsString(pod));
                    return new ResponseEntity<>(pod, HttpStatus.OK);
                }
            }
        } catch (Exception ex) {
            LOGGER.error("Unable to obtain or print Pod information", ex);
        }
        return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
    }

    private Pod getCurrentPod(KubernetesClient kubernetesClient) {
        String hostName = System.getenv(HOSTNAME);
        try {
            if (isServiceAccount() && Strings.isNotBlank(hostName)) {
                return kubernetesClient.pods().withName(hostName).get();
            }
        } catch (Throwable t) {
            LOGGER.debug("Unable to locate pod with name {}.", hostName);
        }
        return null;
    }

    private boolean isServiceAccount() {
        return Paths.get(Config.KUBERNETES_SERVICE_ACCOUNT_TOKEN_PATH).toFile().exists()
                && Paths.get(Config.KUBERNETES_SERVICE_ACCOUNT_CA_CRT_PATH).toFile().exists();
    }

}