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Version: v0.5

How to Create a Template

This tutorial explains how to create a Alibaba Cloud EC2 template and use it to create a service of ECS instance(s) on Alibaba Cloud.

Prerequisites

  1. A GitHub Repository for storing the template.
  2. Walrus installed.

Create a repository on GitHub

  1. Create a new repository on GitHub of your own. Here we use the repository demo
  2. Clone the repository to your local machine.
git clone git@github.com:walrus-catalog-demo/demo.git

Create Template Files

  1. Go to the cloned repository directory.
cd demo

Create files in the directory as follows:

- demo
- main.tf
- outputs.tf
- variables.tf
- README.md

The main.tf file defines the resources to be created. Here we define resource for the template to create an Alibaba Cloud ECS instance.

resource "alicloud_instance" "example" {
instance_name = "demo-instance"
instance_type = var.instance_type
image_id = var.image_id
system_disk_category = var.system_disk_category
system_disk_size = var.system_disk_size
internet_charge_type = var.internet_charge_type
internet_max_bandwidth_out = var.internet_max_bandwidth_out

vswitch_id = data.alicloud_vswitches.default.vswitches.0.id

host_name = var.hostname
key_name = "seal-demo"

security_groups = [
data.alicloud_security_groups.default.groups.0.id
]
}

data "alicloud_vpcs" "default" {
name_regex = "default"
}

data "alicloud_vswitches" "default" {
vpc_id = data.alicloud_vpcs.default.vpcs.0.id
}

data "alicloud_security_groups" "default" {
name_regex = "default"
}

resource "null_resource" "health_check" {
depends_on = [
alicloud_instance.example,
]
}

The variables.tf file defines the variables used in the template. Walrus will use the variables to generate the form for users to fill in.

Walrus use the @label and @group annotations to define the labels and groups of the variables. The optional @options annotation is used to define the dropdown options of the variable, if the @options annotation is not defined, the variable will be displayed as a text box in the form. More details about the annotations can be found here.

In this example, we define two groups: Basic and Advanced. It will be displayed as two tabs in the form when creating a service using this template.

# @label "Instance type"
# @group "Basic"
variable "instance_type" {
description = "The instance type of the ECS instance"
default = "ecs.s6-c1m2.small"
}

# @label "VM image id"
# @group "Basic"
variable "image_id" {
description = "The ID of the image used to launch the ECS instance"
default = "ubuntu_18_04_x64_20G_alibase_20230208.vhd"
}

# @label "System disk type"
# @group "Basic"
# @options ["ephemeral_ssd", "cloud_efficiency", "cloud_ssd", "cloud_essd", "cloud", "cloud_auto"]
variable "system_disk_category" {
description = "The category of the system disk"
default = "cloud_efficiency"
}

# @label "System disk size"
# @group "Basic"
variable "system_disk_size" {
description = "The size of the system disk, value range: [20, 500]"
default = 40
}

# @label "Hostname"
# @group "Basic"
variable "hostname" {
type = string
description = "The hostname of the ECS instance"
default = ""
}

# @label "Network billing type"
# @group "Advanced"
# @options ["PayByTraffic", "PayByBandwidth"]
variable "internet_charge_type" {
description = "The billing method of the public network bandwidth"
default = "PayByTraffic"
}

# @label "Max outbound bandwidth (MB)"
# @group "Advanced"
variable "internet_max_bandwidth_out" {
description = "The maximum outbound bandwidth of the public network"
default = 5
}

The outputs.tf file defines the outputs of the template which will be displayed to the user after the service is created. The outputs of the template of a service could also be referenced by other services.

output "public_ip" {
value = alicloud_instance.example.public_ip
}

output "primary_ip_address" {
value = alicloud_instance.example.primary_ip_address
}

The README.md file is the description of the template. It will be displayed to the user when creating a service using this template. Here we can use the tool terraform-docs to generate the description of the template.

terraform-docs markdown . > README.md

The generated README.md file is as follows:

## Requirements

No requirements.

## Providers

| Name | Version |
|------|---------|
| <a name="provider_alicloud"></a> [alicloud](#provider\_alicloud) | n/a |
| <a name="provider_null"></a> [null](#provider\_null) | n/a |

## Modules

No modules.

## Resources

| Name | Type |
|------|------|
| [alicloud_instance.example](https://registry.terraform.io/providers/hashicorp/alicloud/latest/docs/resources/instance) | resource |
| [null_resource.health_check](https://registry.terraform.io/providers/hashicorp/null/latest/docs/resources/resource) | resource |
| [alicloud_security_groups.default](https://registry.terraform.io/providers/hashicorp/alicloud/latest/docs/data-sources/security_groups) | data source |
| [alicloud_vpcs.default](https://registry.terraform.io/providers/hashicorp/alicloud/latest/docs/data-sources/vpcs) | data source |
| [alicloud_vswitches.default](https://registry.terraform.io/providers/hashicorp/alicloud/latest/docs/data-sources/vswitches) | data source |

## Inputs

| Name | Description | Type | Default | Required |
|------|-------------|------|---------|:--------:|
| <a name="input_hostname"></a> [hostname](#input\_hostname) | The hostname of the ECS instance | `string` | `""` | no |
| <a name="input_image_id"></a> [image\_id](#input\_image\_id) | The ID of the image used to launch the ECS instance | `string` | `"ubuntu_18_04_x64_20G_alibase_20230208.vhd"` | no |
| <a name="input_instance_type"></a> [instance\_type](#input\_instance\_type) | The instance type of the ECS instance | `string` | `"ecs.s6-c1m2.small"` | no |
| <a name="input_internet_charge_type"></a> [internet\_charge\_type](#input\_internet\_charge\_type) | The billing method of the public network bandwidth | `string` | `"PayByTraffic"` | no |
| <a name="input_internet_max_bandwidth_out"></a> [internet\_max\_bandwidth\_out](#input\_internet\_max\_bandwidth\_out) | The maximum outbound bandwidth of the public network | `number` | `5` | no |
| <a name="input_system_disk_category"></a> [system\_disk\_category](#input\_system\_disk\_category) | The category of the system disk | `string` | `"cloud_efficiency"` | no |
| <a name="input_system_disk_size"></a> [system\_disk\_size](#input\_system\_disk\_size) | The size of the system disk, value range: [20, 500] | `number` | `40` | no |

## Outputs

| Name | Description |
|------|-------------|
| <a name="output_primary_ip_address"></a> [primary\_ip\_address](#output\_primary\_ip\_address) | n/a |
| <a name="output_public_ip"></a> [public\_ip](#output\_public\_ip) | n/a |

Commit and Tag Version

git add .
git commit -m "add template files"
git push -u origin main

Create a tag for the template version.

git tag v0.0.1
git push --tags

Create a Template on Walrus

  1. Open Walrus in your browser and log in.
  2. Go to the Template tab under Operations Hub and create a template by using the template we just created, here we name the template aliyun-ec2. create-template After the import task is completed, the template will be displayed in the template list, we can see the template version is v0.0.1. template-version
  3. Add Alibaba Cloud Provider in the Connectors tab under Operations Hub.
  4. Add Connector to the Environment.
  5. Create a Service using the template aliyun-ec2, the form group and labels are generated according to the annotations in the template variables we defined. create-service

After the service is created, we can see the details of the service and the outputs of the template. service-detail Check the ECS instance on Alibaba Cloud console, we can see the ECS instance is created successfully. ecs-instance