elasticsearch/docs/plugins/discovery-ec2.asciidoc

[[discovery-ec2]]
=== EC2 Discovery Plugin

The EC2 discovery plugin uses the https://github.com/aws/aws-sdk-java[AWS API] for unicast discovery.

[[discovery-ec2-install]]
[float]
==== Installation

This plugin can be installed using the plugin manager:

[source,sh]
----------------------------------------------------------------
sudo bin/plugin install discovery-ec2
----------------------------------------------------------------

The plugin must be installed on every node in the cluster, and each node must
be restarted after installation.

[[discovery-ec2-remove]]
[float]
==== Removal

The plugin can be removed with the following command:

[source,sh]
----------------------------------------------------------------
sudo bin/plugin remove discovery-ec2
----------------------------------------------------------------

The node must be stopped before removing the plugin.

[[discovery-ec2-usage]]
==== Getting started with AWS

The plugin will default to using
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html[IAM Role]
credentials for authentication. These can be overridden by, in increasing
order of precedence, system properties `aws.accessKeyId` and `aws.secretKey`,
environment variables `AWS_ACCESS_KEY_ID` and `AWS_SECRET_KEY`, or the
elasticsearch config using `cloud.aws.access_key` and `cloud.aws.secret_key`:

[source,yaml]
----
cloud:
    aws:
        access_key: AKVAIQBF2RECL7FJWGJQ
        secret_key: vExyMThREXeRMm/b/LRzEB8jWwvzQeXgjqMX+6br
----

[[discovery-ec2-usage-security]]
===== Transport security

By default this plugin uses HTTPS for all API calls to AWS endpoints. If you wish to configure HTTP you can set
`cloud.aws.protocol` in the elasticsearch config. You can optionally override this setting per individual service
via: `cloud.aws.ec2.protocol` or `cloud.aws.s3.protocol`.

[source,yaml]
----
cloud:
    aws:
        protocol: https
        ec2:
            protocol: https
----

In addition, a proxy can be configured with the `proxy_host` and `proxy_port` settings (note that protocol can be
`http` or `https`):

[source,yaml]
----
cloud:
    aws:
        protocol: https
        proxy_host: proxy1.company.com
        proxy_port: 8083
----

You can also set different proxies for `ec2` and `s3`:

[source,yaml]
----
cloud:
    aws:
        s3:
            proxy_host: proxy1.company.com
            proxy_port: 8083
        ec2:
            proxy_host: proxy2.company.com
            proxy_port: 8083
----

[[discovery-ec2-usage-region]]
===== Region

The `cloud.aws.region` can be set to a region and will automatically use the relevant settings for both `ec2` and `s3`.
The available values are:

* `us-east` (`us-east-1`)
* `us-west` (`us-west-1`)
* `us-west-1`
* `us-west-2`
* `ap-southeast` (`ap-southeast-1`)
* `ap-southeast-1`
* `ap-southeast-2`
* `ap-northeast` (`ap-northeast-1`)
* `eu-west` (`eu-west-1`)
* `eu-central` (`eu-central-1`)
* `sa-east` (`sa-east-1`)
* `cn-north` (`cn-north-1`)

[[discovery-ec2-usage-signer]]
===== EC2 Signer API

If you are using a compatible EC2 service, they might be using an older API to sign the requests.
You can set your compatible signer API using `cloud.aws.signer` (or `cloud.aws.ec2.signer`)
with the right signer to use.

[[discovery-ec2-discovery]]
==== EC2 Discovery

ec2 discovery allows to use the ec2 APIs to perform automatic discovery (similar to multicast in non hostile multicast
environments). Here is a simple sample configuration:

[source,yaml]
----
discovery:
    type: ec2
----

You must also set `cloud.aws.region` if you are not using default AWS region. See <<discovery-ec2-usage-region>> for details.

The ec2 discovery is using the same credentials as the rest of the AWS services provided by this plugin (`repositories`).
See <<discovery-ec2-usage>> for details. 

The following are a list of settings (prefixed with `discovery.ec2`) that can further control the discovery:

`groups`::

    Either a comma separated list or array based list of (security) groups.
    Only instances with the provided security groups will be used in the
    cluster discovery. (NOTE: You could provide either group NAME or group
    ID.)

`host_type`::

    The type of host type to use to communicate with other instances. Can be
    one of `private_ip`, `public_ip`, `private_dns`, `public_dns`. Defaults to
    `private_ip`.

`availability_zones`::

    Either a comma separated list or array based list of availability zones.
    Only instances within the provided availability zones will be used in the
    cluster discovery.

`any_group`::

    If set to `false`, will require all security groups to be present for the
    instance to be used for the discovery. Defaults to `true`.

`ping_timeout`::

    How long to wait for existing EC2 nodes to reply during discovery.
    Defaults to `3s`. If no unit like `ms`, `s` or `m` is specified,
    milliseconds are used.


[IMPORTANT]
.Binding the network host
==============================================

It's important to define `network.host` as by default it's bound to `localhost`.

You can use {ref}/modules-network.html[core network host settings] or
<<discovery-ec2-network-host,ec2 specific host settings>>:

==============================================

[[discovery-ec2-network-host]]
==== EC2 Network Host

When the `discovery-ec2` plugin is installed, the following are also allowed
as valid network host settings:

[cols="<,<",options="header",]
|==================================================================
|EC2 Host Value |Description
|`_ec2:privateIpv4_` |The private IP address (ipv4) of the machine.
|`_ec2:privateDns_` |The private host of the machine.
|`_ec2:publicIpv4_` |The public IP address (ipv4) of the machine.
|`_ec2:publicDns_` |The public host of the machine.
|`_ec2:privateIp_` |equivalent to _ec2:privateIpv4_.
|`_ec2:publicIp_` |equivalent to _ec2:publicIpv4_.
|`_ec2_` |equivalent to _ec2:privateIpv4_.
|==================================================================


[[discovery-ec2-permissions]]
===== Recommended EC2 Permissions

EC2 discovery requires making a call to the EC2 service. You'll want to setup
an IAM policy to allow this. You can create a custom policy via the IAM
Management Console. It should look similar to this.

[source,js]
----
{
  "Statement": [
    {
      "Action": [
        "ec2:DescribeInstances"
      ],
      "Effect": "Allow",
      "Resource": [
        "*"
      ]
    }
  ],
  "Version": "2012-10-17"
}
----

[[discovery-ec2-filtering]]
===== Filtering by Tags

The ec2 discovery can also filter machines to include in the cluster based on tags (and not just groups). The settings
to use include the `discovery.ec2.tag.` prefix. For example, setting `discovery.ec2.tag.stage` to `dev` will only
filter instances with a tag key set to `stage`, and a value of `dev`. Several tags set will require all of those tags
to be set for the instance to be included.

One practical use for tag filtering is when an ec2 cluster contains many nodes that are not running elasticsearch. In
this case (particularly with high `ping_timeout` values) there is a risk that a new node's discovery phase will end
before it has found the cluster (which will result in it declaring itself master of a new cluster with the same name
- highly undesirable). Tagging elasticsearch ec2 nodes and then filtering by that tag will resolve this issue.

[[discovery-ec2-attributes]]
===== Automatic Node Attributes

Though not dependent on actually using `ec2` as discovery (but still requires the cloud aws plugin installed), the
plugin can automatically add node attributes relating to ec2 (for example, availability zone, that can be used with
the awareness allocation feature). In order to enable it, set `cloud.node.auto_attributes` to `true` in the settings.

[[discovery-ec2-endpoint]]
===== Using other EC2 endpoint

If you are using any EC2 api compatible service, you can set the endpoint you want to use by setting
`cloud.aws.ec2.endpoint` to your URL provider.