InjectableTag.java

/**
 * Copyright 2013 Netflix, Inc.
 * <p/>
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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 com.netflix.servo.tag;

import org.slf4j.LoggerFactory;

import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * Group of Tags whose values will be dynamically set at runtime
 * based on local calls.
 */
public enum InjectableTag implements Tag {
  /**
   * The current hostname.
   */
  HOSTNAME("hostname", getHostName()),

  /**
   * The ip for localhost.
   */
  IP("ip", getIp());

  private final String key;
  private final String value;

  InjectableTag(String key, String val) {
    this.key = key;
    this.value = val;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public String getKey() {
    return key;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public String getValue() {
    return value;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public String tagString() {
    return key + "=" + value;
  }

  private static String getHostName() {
    return (loadAddress() != null) ? loadAddress().getHostName() : "unkownHost";
  }

  private static String getIp() {
    return (loadAddress() != null) ? loadAddress().getHostAddress() : "unknownHost";
  }

  private static InetAddress loadAddress() {
    try {
      return InetAddress.getLocalHost();
    } catch (UnknownHostException e) {
      LoggerFactory.getLogger(InjectableTag.class).warn("Unable to load INET info.", e);
      return null;
    }
  }
}