---
layout: docs
page_title: AWS dynamic host catalogs
description: |-
  An overview of AWS host discovery in Boundary
---
# AWS dynamic host catalogs
Boundary uses dynamic host catalogs to automatically discover AWS EC2 instances and add them as hosts.

## Create a host catalog to connect with AWS
Boundary uses plugins to integrate with a variety of providers. To use
a dynamic host catalog to integrate with AWS, you create a host catalog of the `plugin` type
and set the `plugin-name` value to `aws`. You must also provide the specific
fields needed for Boundary to authenticate with AWS.

<Tabs>
<Tab heading="CLI">

```shell-session
$ boundary host-catalogs create plugin \
  -scope-id $BOUNDARY_PROJECT_ID \
  -plugin-name aws \
  -attr disable_credential_rotation=true \
  -attr region=us-east-1 \
  -secret access_key_id=env://AWS_ACCESS_KEY_ID \
  -secret secret_access_key=env://AWS_SECRET_ACCESS_KEY
```

</Tab>
<Tab heading="Terraform">

  ```hcl
  resource "boundary_host_catalog_plugin" "aws_host_catalog" {
    name        = "AWS Catalog"
    description = "AWS Host Catalog"
    scope_id    = boundary_scope.project.id
    plugin_name = "aws"

    attributes_json = jsonencode({
      "region" = "eu-west-2",
      "disable_credential_rotation" = true })
    secrets_json = jsonencode({
      "access_key_id" = var.aws_access,
      "secret_access_key" = var.aws_secret})
  }
  ```

</Tab>
</Tabs>

The `scope-id` and `plugin-name` fields are required when you create a
  dynamic host catalog.

The fields following the `attr` and `secret` flags are specific to AWS and are required by
  Boundary for authentication.

- `disable_credential_rotation`: When set to `true`, Boundary will not rotate the credentials with AWS automatically.
- `region`: The region to configure the host catalog for. All host sets in this
  catalog will be configured for this region.
- `role_arn`: The AWS role ARN used for `AssumeRole` authentication. If you provide a `role_arn` value, you must also set `disable_credential_rotation` to `true`.
- `role_external_id`: The external ID that you configured for the `AssumeRole` provider.
- `role_session_name`: The session name that you configured for the `AssumeRole` provider.
- `role_tags`: The key-value pair tags that you configured for the `AssumeRole` provider.
- `access_key_id`: The access key ID for the IAM user to use with this host
  catalog.
- `secret_access_key`: The secret access key for the IAM user to use with this
  host catalog.


Refer to [the domain model documentation](/boundary/docs/concepts/domain-model/host-catalogs) for additional fields that you can use when you create host catalogs.

## Create a host set to connect with AWS
[Host sets](/boundary/docs/concepts/domain-model/host-sets) specify which AWS
  filters should be used to identify the discovered hosts that should be added as members.

Create a host set using the following command:

<Tabs>
<Tab heading="CLI" group="cli">

```shell-session
$ boundary host-sets create plugin \
  -host-catalog-id $BOUNDARY_HOST_CATALOG_ID \
  -attr filters=tag-key=foo,bar \
  -attr filters=tag-key=baz
```

</Tab>
<Tab heading="Terraform" group="terraform">

```hcl
resource "boundary_host_set_plugin" "aws_host_set" {
  name        = "AWS Host Set"
  description = "AWS Host Set"
  host_catalog_id  = boundary_scope.aws_host_catalog.id
  attributes_json = jsonencode({
  "filters" = ["tag-key=foo,bar", "tag-key=baz"] })
}
```

</Tab>
</Tabs>

The `host-catalog-id` value is a required field that specifies in which host catalog to
  create this host set.

Like with the host catalog, the fields passed in after the `attr` flag are
 specific to AWS.

The `filters` field contains string filters in the format key=val1,val2. The key corresponds to
  a filter option, and the value(s) are a comma-separated list. For a list of
  filter options, refer to the
  [describe-instances in the AWS CLI reference](https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-instances.html).
  When the values in a single `filters` field are separated by a comma, either
  can be true for the host to match.  When multiple filters fields are provided,
  they must all match for a host to match. In the example above, an instance must
  have either tags `foo` or `bar`, and must have the tag `baz`.

For more fields that you can use when creating host sets, refer to
  [the domain model documentation](/boundary/docs/concepts/domain-model/host-sets).