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Common utility classes for building Amazon AWS-based cloud pools.
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package com.elastisys.scale.cloudpool.aws.commons.requests.ec2;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import com.amazonaws.ClientConfiguration;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.services.ec2.model.DescribeInstancesRequest;
import com.amazonaws.services.ec2.model.DescribeInstancesResult;
import com.amazonaws.services.ec2.model.Filter;
import com.amazonaws.services.ec2.model.Instance;
import com.amazonaws.services.ec2.model.Reservation;
import com.elastisys.scale.commons.net.retryable.Retryable;
import com.elastisys.scale.commons.net.retryable.Retryers;
/**
* A {@link Callable} task that, when executed, requests meta data for AWS EC2
* machine instances in a region.
*
* The query can be limited to only return meta data for a particular group of
* instances. Furthermore, query {@link Filter}s can be supplied to further
* narrow down the result set. Note that without {@link Filter}s, the result may
* contain instances in all states: pending, running, terminated, etc.
*
* AWS limits the number of filter values to some number (at the time of
* writing, that number is 200). For a detailed description of supported
* {@link Filter}s refer to the Amazon EC2 API.
*
* Note that due to the eventual consistency semantics of the Amazon API, a recently created EC2
* instance or spot instance request may not be immediately available for
* tagging. Therefore, it might be wise to use a retry strategy (with
* exponential back-off) when tagging a recently created resource.
*
* @see Retryable
* @see Retryers
*/
public class GetInstances extends AmazonEc2Request> {
/**
* A list of instance ids of interest to limit the query to. If specified,
* meta data will only be fetched for these instances. If null
* or empty list, meta data will be fetched for all instances.
*/
private List instanceIds;
/**
* An (optional) list of filter to narrow the query. Only instances matching
* the given filters will be returned. May be null.
*/
private List filters;
/**
* Constructs a new {@link GetInstances} task that will fetch all instances
* in the region.
*
* @param awsCredentials
* The AWS security credentials to the account.
* @param region
* The AWS region of interest.
* @param clientConfig
* Client configuration options such as connection timeout, etc.
*/
public GetInstances(AWSCredentials awsCredentials, String region, ClientConfiguration clientConfig) {
super(awsCredentials, region, clientConfig);
this.instanceIds = null;
this.filters = null;
}
/**
* Constructs a new {@link GetInstances} task that will fetch instances in
* the region that match any of the specified instance ids.
*
* @param awsCredentials
* The AWS security credentials to the account.
* @param region
* The AWS region of interest.
* @param clientConfig
* Client configuration options such as connection timeout, etc.
* @param instanceIds
* A list of instance ids of interest to limit the query to. If
* null or empty list, meta data will be fetched for
* all instances.
*/
public GetInstances(AWSCredentials awsCredentials, String region, ClientConfiguration clientConfig,
List instanceIds) {
super(awsCredentials, region, clientConfig);
this.instanceIds = instanceIds;
this.filters = null;
}
/**
* Constructs a new {@link GetInstances} task that will fetch instances in
* the region that match any of the specified instance ids and satisfy the
* given filters.
*
* @param awsCredentials
* The AWS security credentials to the account.
* @param region
* The AWS region of interest.
* @param clientConfig
* Client configuration options such as connection timeout, etc.
* @param instanceIds
* A list of instance ids of interest to limit the query to. If
* null or empty list, meta data will be fetched for
* all instances.
* @param filters
* A list of filter to narrow the query. Only instances matching
* the given filters will be returned. May be null.
*/
public GetInstances(AWSCredentials awsCredentials, String region, ClientConfiguration clientConfig,
List instanceIds, List filters) {
super(awsCredentials, region, clientConfig);
this.instanceIds = instanceIds;
this.filters = filters;
}
/**
* Sets {@link Filter}s that will be used to narrow down the query when
* {@link #call()}ed.
*
* @param filters
* A list of filter to narrow the query. Only instances matching
* the given filters will be returned.
* @return
*/
public GetInstances withFilters(List filters) {
this.filters = filters;
return this;
}
/**
* Sets an instance id filter that will be used to narrow down the result
* set when the query is {@link #call()}ed.
*
* @param filters
* A list of instance ids of interest to limit the query to. If
* null or empty list, meta data will be fetched for
* all instances.
*/
public GetInstances withInstanceIds(List instanceIds) {
this.instanceIds = instanceIds;
return this;
}
@Override
public List call() {
List instances = new ArrayList<>();
DescribeInstancesRequest request = new DescribeInstancesRequest();
request.withInstanceIds(this.instanceIds);
request.withFilters(this.filters);
// paginate through result as long as there is another response token
boolean moreResults = false;
do {
DescribeInstancesResult result = getClient().getApi().describeInstances(request);
instances.addAll(instances(result));
moreResults = result.getNextToken() != null && !result.getNextToken().equals("");
request.setNextToken(result.getNextToken());
} while (moreResults);
return instances;
}
private List instances(DescribeInstancesResult result) {
List instances = new ArrayList<>();
List reservations = result.getReservations();
for (Reservation reservation : reservations) {
instances.addAll(reservation.getInstances());
}
return instances;
}
}