AwsInjectableTag.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.aws;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.DefaultAWSCredentialsProviderChain;
import com.amazonaws.auth.PropertiesCredentials;
import com.amazonaws.services.autoscaling.AmazonAutoScaling;
import com.amazonaws.services.autoscaling.model.AutoScalingInstanceDetails;
import com.amazonaws.services.autoscaling.model.DescribeAutoScalingInstancesRequest;
import com.netflix.servo.aws.AwsPropertyKeys;
import com.netflix.servo.aws.AwsServiceClients;
import com.netflix.servo.aws.constants.Dimensions;
import com.netflix.servo.tag.Tag;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.List;

/**
 * Group of Tags who's values will be dynamically set at runtime
 * based on amazon api calls.
 * <p/>
 * The keys for and values of these Tags are consistent with AWS naming.
 */
public enum AwsInjectableTag implements Tag {
  AUTOSCALE_GROUP(Dimensions.AUTOSCALING_GROUP.getAwsString(), getAutoScaleGroup()),
  INSTANCE_ID(Dimensions.INSTANCE_ID.getAwsString(), getInstanceId()),
  AVAILABILITY_ZONE(Dimensions.AVAILABILITY_ZONE.getAwsString(), getZone()),
  AMI_ID(Dimensions.AMI_IMAGE_ID.getAwsString(), getAmiId()),
  INSTANCE_TYPE(Dimensions.INSTANCE_TYPE.getAwsString(), getInstanceType()),
  LOCAL_HOSTNAME("local-hostname", getLocalHostname()),
  LOCAL_IPV4("local-ipv4", getLocalIpv4()),
  PUBLIC_HOSTNAME("public-hostname", getPublicHostname()),
  PUBLIC_IPV4("public-ipv4", getPublicIpv4());

  private static final String METADATA_URL = "http://instance-data/latest/meta-data";
  private static final String UNDEFINED = "undefined";

  private static Logger getLogger() {
    return LoggerFactory.getLogger(AwsInjectableTag.class);
  }

  private final String key;
  private final String value;

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

  /**
   * @return Amazon compliant string representation of the key.
   */
  public String getKey() {
    return key;
  }

  /**
   * @return value as determined at runtime for the key.
   */
  public String getValue() {
    return value;
  }

  public String tagString() {
    return key + "=" + value;
  }

  static String getAutoScaleGroup() {
    try {
      String credFileProperty = System.getProperties().getProperty(
          AwsPropertyKeys.AWS_CREDENTIALS_FILE.getBundle());
      AWSCredentials credentials;

      if (credFileProperty != null) {
        credentials = new PropertiesCredentials(new File(credFileProperty));
      } else {
        credentials = new DefaultAWSCredentialsProviderChain().getCredentials();
      }

      AmazonAutoScaling autoScalingClient = AwsServiceClients.autoScaling(credentials);

      List<AutoScalingInstanceDetails> autoScalingInstances = autoScalingClient.describeAutoScalingInstances(
          new DescribeAutoScalingInstancesRequest().withInstanceIds(getInstanceId())).getAutoScalingInstances();
	  return autoScalingInstances.isEmpty() ? UNDEFINED : autoScalingInstances.get(0).getAutoScalingGroupName();
    } catch (Exception e) {
      getLogger().error("Unable to get ASG name.", e);
      return UNDEFINED;
    }
  }

  static String getInstanceId() {
    return getUrlValue("/instance-id");
  }

  @SuppressWarnings("PMD")
  static String getUrlValue(String path) {
    BufferedReader reader = null;
    try {
      URL url = new URL(METADATA_URL + path);
      reader = new BufferedReader(new InputStreamReader(url.openStream(),
          Charset.forName("UTF-8")));
      return reader.readLine();
    } catch (Exception e) {
      getLogger().warn("Unable to read value from AWS metadata URL", e);
      return UNDEFINED;
    } finally {
      try {
        if (reader != null) {
          reader.close();
        }
      } catch (IOException e) {
        getLogger().info("Ignoring failure while closing the stream", e);
      }
    }
  }

  static String getZone() {
    return getUrlValue("/placement/availability-zone");
  }

  static String getAmiId() {
    return getUrlValue("/ami-id");
  }

  static String getInstanceType() {
    return getUrlValue("/instance-type");
  }

  static String getLocalHostname() {
    return getUrlValue("/local-hostname");
  }

  static String getLocalIpv4() {
    return getUrlValue("/local-ipv4");
  }

  static String getPublicHostname() {
    return getUrlValue("/public-hostname");
  }

  static String getPublicIpv4() {
    return getUrlValue("/public-ipv4");
  }
}