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= Discovery in the Cloud

:javaFile: {javaCodeDir}/DiscoveryInTheCloud.java

Nodes discovery on a cloud platform is usually proven to be more
challenging because most virtual environments are subject to the
following limitations:

* Multicast is disabled;
* TCP addresses change every time a new image is started.

Although you can use TCP-based discovery in the absence of the
Multicast, you still have to deal with constantly changing IP addresses.
This causes a serious inconvenience and makes configurations based on
static IPs virtually unusable in such environments.

To mitigate the constantly changing IP addresses problem, Ignite supports a number of IP finders designed to work in the cloud:

* Apache jclouds IP Finder
* Amazon S3 IP Finder
* Amazon ELB IP Finder
* Google Cloud Storage IP Finder


TIP: Cloud-based IP Finders allow you to create your configuration once and reuse it for all instances.

== Apache jclouds IP Finder

To mitigate the constantly changing IP addresses problem, Ignite supports automatic node discovery by utilizing Apache jclouds multi-cloud toolkit via `TcpDiscoveryCloudIpFinder`.
For information about Apache jclouds please refer to https://jclouds.apache.org[jclouds.apache.org].

The IP finder forms nodes addresses by getting the private and public IP addresses of all virtual machines running on the cloud and adding a port number to them.
The port is the one that is set with either `TcpDiscoverySpi.setLocalPort(int)` or `TcpDiscoverySpi.DFLT_PORT`.
This way all the nodes can try to connect to any formed IP address and initiate automatic grid node discovery.

Refer to https://jclouds.apache.org/reference/providers/#compute[Apache jclouds providers section] to get the list of supported cloud platforms.

CAUTION: All virtual machines must start Ignite instances on the same port, otherwise they will not be able to discover each other using this IP finder.

Here is an example of how to configure Apache jclouds based IP finder:


[tabs]
--
tab:XML[]
[source,xml]
----
<bean class="org.apache.ignite.configuration.IgniteConfiguration">
  <property name="discoverySpi">
    <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
      <property name="ipFinder">
        <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.cloud.TcpDiscoveryCloudIpFinder">
            <!-- Configuration for Google Compute Engine. -->
            <property name="provider" value="google-compute-engine"/>
            <property name="identity" value="YOUR_SERVICE_ACCOUNT_EMAIL"/>
            <property name="credentialPath" value="PATH_YOUR_PEM_FILE"/>
            <property name="zones">
            <list>
                <value>us-central1-a</value>
                <value>asia-east1-a</value>
            </list>
            </property>
        </bean>
      </property>
    </bean>
  </property>
</bean>
----

tab:Java[]
[source,java]
----
include::{javaFile}[tag=jclouds,indent=0]
----
tab:C#/.NET[unsupported]
tab:C++[unsupported]
--


== Amazon S3 IP Finder

Amazon S3-based discovery allows Ignite nodes to register their IP addresses on start-up in an Amazon S3 store.
This way other nodes can try to connect to any of the IP addresses stored in S3 and initiate automatic node discovery.
To use S3 based automatic node discovery, you need to configure the `TcpDiscoveryS3IpFindera` type of `ipFinder`.

CAUTION: You must link:setup#enabling-modules[enable the 'ignite-aws' module].

Here is an example of how to configure Amazon S3 based IP finder:


[tabs]
--
tab:XML[]
[source,xml]
----
<bean class="org.apache.ignite.configuration.IgniteConfiguration">

  <property name="discoverySpi">
    <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
      <property name="ipFinder">
        <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.s3.TcpDiscoveryS3IpFinder">
          <property name="awsCredentials" ref="aws.creds"/>
          <property name="bucketName" value="YOUR_BUCKET_NAME"/>
        </bean>
      </property>
    </bean>
  </property>
</bean>

<!-- AWS credentials. Provide your access key ID and secret access key. -->
<bean id="aws.creds" class="com.amazonaws.auth.BasicAWSCredentials">
  <constructor-arg value="YOUR_ACCESS_KEY_ID" />
  <constructor-arg value="YOUR_SECRET_ACCESS_KEY" />
</bean>
----

tab:Java[]
[source,java]
----
include::{javaFile}[tag=aws1,indent=0]
----

tab:C#/.NET[unsupported]
tab:C++[unsupported]
--

You can also use *Instance Profile* for AWS credentials provider.

[tabs]
--
tab:XML[]
[source,xml]
----
<bean class="org.apache.ignite.configuration.IgniteConfiguration">

  <property name="discoverySpi">
    <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
      <property name="ipFinder">
        <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.s3.TcpDiscoveryS3IpFinder">
          <property name="awsCredentialsProvider" ref="aws.creds"/>
          <property name="bucketName" value="YOUR_BUCKET_NAME"/>
        </bean>
      </property>
    </bean>
  </property>
</bean>

<!-- Instance Profile based credentials -->
<bean id="aws.creds" class="com.amazonaws.auth.InstanceProfileCredentialsProvider">
  <constructor-arg value="false" />
</bean>
----

tab:Java[]
[source,java]
----
include::{javaFile}[tag=aws2,indent=0]
----
tab:C#/.NET[unsupported]
tab:C++[unsupported]
--


== Amazon ELB Based Discovery

AWS ELB-based IP finder does not require nodes to register their IP
addresses. The IP finder automatically fetches addresses of all the
nodes connected under an ELB and uses them to connect to the cluster. To
use ELB based automatic node discovery, you need to configure the
`TcpDiscoveryElbIpFinder` type of `ipFinder`.

Here is an example of how to configure Amazon ELB based IP finder:


[tabs]
--
tab:XML[]
[source,xml]
----
<bean class="org.apache.ignite.configuration.IgniteConfiguration">

  <property name="discoverySpi">
    <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
      <property name="ipFinder">
        <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.elb.TcpDiscoveryElbIpFinder">
          <property name="credentialsProvider">
              <bean class="com.amazonaws.auth.AWSStaticCredentialsProvider">
                  <constructor-arg ref="aws.creds"/>
              </bean>
          </property>
          <property name="region" value="YOUR_ELB_REGION_NAME"/>
          <property name="loadBalancerName" value="YOUR_AWS_ELB_NAME"/>
        </bean>
      </property>
    </bean>
  </property>
</bean>

<!-- AWS credentials. Provide your access key ID and secret access key. -->
<bean id="aws.creds" class="com.amazonaws.auth.BasicAWSCredentials">
  <constructor-arg value="YOUR_ACCESS_KEY_ID" />
  <constructor-arg value="YOUR_SECRET_ACCESS_KEY" />
</bean>
----

tab:Java[]
[source,java]
----
include::{javaFile}[tag=awsElb,indent=0]
----

tab:C#/.NET[unsupported]
tab:C++[unsupported]
--


== Google Compute Discovery

Ignite supports automatic node discovery by utilizing Google Cloud Storage store.
This mechanism is implemented in `TcpDiscoveryGoogleStorageIpFinder`.
On start-up, each node registers its IP address in the storage and discovers other nodes by reading the storage.

IMPORTANT: To use `TcpDiscoveryGoogleStorageIpFinder`, enable the `ignite-gce` link:setup#enabling-modules[module] in your application.

Here is an example of how to configure Google Cloud Storage based IP finder:

[tabs]
--
tab:XML[]
[source,xml]
----
<bean class="org.apache.ignite.configuration.IgniteConfiguration">

  <property name="discoverySpi">
    <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
      <property name="ipFinder">
        <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.gce.TcpDiscoveryGoogleStorageIpFinder">
          <property name="projectName" value="YOUR_GOOGLE_PLATFORM_PROJECT_NAME"/>
          <property name="bucketName" value="YOUR_BUCKET_NAME"/>
          <property name="serviceAccountId" value="YOUR_SERVICE_ACCOUNT_ID"/>
          <property name="serviceAccountP12FilePath" value="PATH_TO_YOUR_PKCS12_KEY"/>
        </bean>
      </property>
    </bean>
  </property>
</bean>
----

tab:Java[]
[source,java]
----
include::{javaFile}[tag=google,indent=0]
----
tab:C#/.NET[unsupported]
tab:C++[unsupported]
--