4.3

CloudFormation template generator

This page shows how to create CloudFormation templates using an API call. The same API calls are used by the Self-Service Portal to generate the CloudFormation template before redirecting to AWS.

Before you begin

The APIs described here require an API token which can be obtained at https://get.weka.io/ui/account/api-tokens. Obtaining this token requires registration if you do not have an account.

API overview

To generate a CloudFormation template, it is first necessary to decide which WEKA system version is to be installed. This is performed using the https://<token>@get.weka.io/dist/v1/release API which provides a list of all available versions:

$ curl https://<token>@get.weka.io/dist/v1/release
{
   "num_results" : 8,
   "page" : 1,
   "page_size" : 50,
   "num_pages" : 1,
   "objects" : [
      {
         "id" : "3.6.1",
         "public" : true,
         "final" : true,
         "trunk_id" : "",
         "s3_path" : "releases/3.6.1"
         .
         .
         .
      },
      ...
   ]
}

This list of releases available for installation is sorted backward from the most recent release. By default, 50 results are provided per page. To receive more results, use the page=N query parameter to receive the Nth page.

Note: Usually, a request for more results is not necessary, since the first page contains the most recent releases.

Each release contains an ID field that identifies the release. In the examples below, version 3.6.1 has been used.

To generate a CloudFormation template, make a POST request to the https://<token>@get.weka.io/dist/v1/aws/cfn/<version>API:

$ spec='
{
  "cluster": [
    {
      "role": "backend",
      "instance_type": "i3en.2xlarge",
      "count": 10
    },
    {
      "role": "client",
      "instance_type": "r3.xlarge",
      "count": 2
    }
  ]
}
'
$ curl -X POST -H 'Content-Type: application/json' -d "$spec" https://<token>@get.weka.io/dist/v1/aws/cfn/3.6.1
{
   "url" : "https://wekaio-cfn-templates-prod.s3.amazonaws.com/cjibjp7ps000001o9pncqywv6.json",
   "quick_create_stack" : {
      "ap-southeast-2" : "...",
      ...
   }
}

In the example above, a template is generated for a cluster with 10 i3en.2xlarge backend instances and 2 r3.xlarge client instances. For details, see the Deployment Types and Supported EC2 instance types sections.

Request body

The https://<token>@get.weka.io/dist/v1/aws/cfn/<version> API provides a JSON object with a cluster property. cluster is a list of instance types, roles, and counts:

Property

Description

role

Either backend or client. See the Deployment Types section.

instance_type

One of the supported instance types, according to the role and supported instances. See the Supported EC2 Instance Types section.

count

The number of instances of this type to include in the template.

ami_id

When role is client, it is possible to specify a custom AMI-ID. For details, see the Custom Client AMI section.

net

Either dedicated or shared, in client role only. For details, see the Dedicated vs. shared client networking section.

It is possible to specify multiple groups of instances by adding more role/instance_type/count objects to the clusterarray, as long as there are at least 6 backend instances (the minimum number of backend instances required to deploy a cluster).

Custom client AMI

When specifying an ami_id in client groups, the specified AMI will be used when launching the client instances. The Weka system will be installed on top of this AMI in a separate EBS volume.

When ami_id is not specified, the client instances are launched with the latest Amazon Linux supported by the Weka system version selected to be installed.

Note the following when using a custom AMI-ID:

  • AMIs are stored per region. Make sure to specify an AMI-ID that matches the region in which the CloudFormation template is deployed.

  • The AMI operating system must be one of the supported operating systems listed in the Prerequisites and compatibility section of the version installed. If the AMI defined is not supported or has an unsupported operating system, the installation may fail, and the CloudFormation stack will not be created successfully.

Dedicated vs. shared client networking

By default, both client and backend instances are launched in the dedicated networking mode. Although this cannot be changed for backends, it can be controlled for client instances.

Dedicated networking means an ENI is created for internal cluster traffic in the client instances. This allows the WEKA system to bypass the kernel and provide throughput only limited by the instance network.

In shared networking, the client shares the instance’s network interface with all traffic passing through the kernel. Although slower, this mode is sometimes desirable when an ENI cannot be allocated or if the operating system does not allow more than one NIC.

Returned result

The returned result is a JSON object with two properties: url and quick_create_stack.

The url property is a URL to an S3 object containing the generated template.

To deploy the CloudFormation template through the AWS console, a quick_create_stack property contains links to the console for each public AWS region. These links are pre-filled with your API token as a parameter to the template.

Note: CloudFormation template URLs are valid for up to 1 week.

It is also possible to receive the template directly from the API call without saving it in a bucket. To do this, use a ?type=templatequery parameter:

$ spec='...'  # same as above
$ curl -X POST -H 'Content-Type: application/json' -d "$spec" https://<token>@get.weka.io/dist/v1/aws/cfn/3.6.1?type=template
{"AWSTemplateFormatVersion": "2010-09-09", ...

CloudFormation template parameters

The CloudFormation stack parameters are described in the Cluster CloudFormation Stack section.

IAM role created in the template

The CloudFormation template contains an instance role that allows the WEKA cluster instances to call the following AWS APIs:

  • ec2:DescribeInstances

  • ec2:DescribeNetworkInterfaces

  • ec2:AttachNetworkInterface

  • ec2:CreateNetworkInterface

  • ec2:ModifyNetworkInterfaceAttribute

  • ec2:DeleteNetworkInterface

In case tiering is configured, additional AWS APIs permissions are given:

  • s3:DeleteObject

  • s3:GetObject

  • s3:PutObject

  • s3:ListBucket

Additional operations

Once a CloudFormation template has been generated, it is possible to create a stack using the AWS console or the AWS CLI.

When the deployment is complete, the stack status updates to CREATE_COMPLETE, and it is possible to access the WEKA cluster GUI by going to the Outputs tab of the CloudFormation stack and clicking the GUI link.

If there is a valid license in get.weka.io, the stack attempts to create a license, deploy it to the cluster, and start IO automatically.

With that, a filesystem is created and mounted on all instances. This shared filesystem is mounted on /mnt/weka in each cluster instance.

If the deployment is unsuccessful, see Troubleshooting for the resolution of common deployment issues.

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