AutoDetectingStackNameProvider.java

/*
 * Copyright 2013-2014 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.aws.core.env.stack.config;

import com.amazonaws.services.cloudformation.AmazonCloudFormation;
import com.amazonaws.services.cloudformation.model.DescribeStackResourcesRequest;
import com.amazonaws.services.cloudformation.model.DescribeStackResourcesResult;
import com.amazonaws.services.ec2.AmazonEC2;
import com.amazonaws.services.ec2.model.DescribeTagsRequest;
import com.amazonaws.services.ec2.model.DescribeTagsResult;
import com.amazonaws.services.ec2.model.Filter;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.cloud.aws.core.env.ec2.AmazonEc2InstanceIdProvider;
import org.springframework.cloud.aws.core.env.ec2.InstanceIdProvider;
import org.springframework.util.Assert;

import java.util.Collections;

/**
 * Represents a stack name provider that automatically detects the current stack name based on the amazon elastic cloud
 * environment.
 *
 * @author Christian Stettler
 * @author Agim Emruli
 */
public class AutoDetectingStackNameProvider implements StackNameProvider, InitializingBean {

    private final AmazonCloudFormation amazonCloudFormationClient;
    private final AmazonEC2 amazonEc2Client;
    private final InstanceIdProvider instanceIdProvider;

    private String stackName;

    private AutoDetectingStackNameProvider(AmazonCloudFormation amazonCloudFormationClient, AmazonEC2 amazonEc2Client, InstanceIdProvider instanceIdProvider) {
        this.amazonCloudFormationClient = amazonCloudFormationClient;
        this.amazonEc2Client = amazonEc2Client;
        this.instanceIdProvider = instanceIdProvider;
        afterPropertiesSet();
    }

    public AutoDetectingStackNameProvider(AmazonCloudFormation amazonCloudFormationClient, AmazonEC2 amazonEc2Client) {
        this(amazonCloudFormationClient, amazonEc2Client, new AmazonEc2InstanceIdProvider());
    }

    @Override
    public void afterPropertiesSet() {
        String instanceId = this.instanceIdProvider.getCurrentInstanceId();
        this.stackName = autoDetectStackName(instanceId);
        if (this.stackName == null) {
            throw new IllegalStateException("No stack resources found in stack for EC2 instance '" + instanceId + "'");
        }
    }

    @Override
    public String getStackName() {
        return this.stackName;
    }

    private String autoDetectStackName(String instanceId) {

        Assert.notNull(instanceId, "No valid instance id defined");
        DescribeStackResourcesResult describeStackResourcesResult = this.amazonCloudFormationClient.describeStackResources(new DescribeStackResourcesRequest().withPhysicalResourceId(instanceId));

        if (describeStackResourcesResult != null && describeStackResourcesResult.getStackResources() != null &&
                !describeStackResourcesResult.getStackResources().isEmpty()) {
            return describeStackResourcesResult.getStackResources().get(0).getStackName();
        }

        if (this.amazonEc2Client != null) {
            DescribeTagsResult describeTagsResult = this.amazonEc2Client.describeTags(new DescribeTagsRequest().withFilters(
                    new Filter("resource-id", Collections.singletonList(instanceId)),
                    new Filter("resource-type", Collections.singletonList("instance")),
                    new Filter("key", Collections.singletonList("aws:cloudformation:stack-name"))));

            if (describeTagsResult != null && describeTagsResult.getTags() != null && !describeTagsResult.getTags().isEmpty()) {
                return describeTagsResult.getTags().get(0).getValue();
            }
        }

        return null;
    }
}