https://github.com/wearetechnative/terraform-aws-ec2-asg

AWS auto scaling is used to scale up and scale down the EC2-instance by depending up on the incoming traffic.
https://github.com/wearetechnative/terraform-aws-ec2-asg

Last synced: 3 months ago
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AWS auto scaling is used to scale up and scale down the EC2-instance by depending up on the incoming traffic.

Host: GitHub
URL: https://github.com/wearetechnative/terraform-aws-ec2-asg
Owner: wearetechnative
License: apache-2.0
Created: 2023-10-18T12:23:20.000Z (over 2 years ago)
Default Branch: main
Last Pushed: 2025-04-22T10:33:11.000Z (about 1 year ago)
Last Synced: 2025-04-22T11:34:58.585Z (about 1 year ago)
Language: HCL
Size: 205 KB
Stars: 0
Watchers: 0
Forks: 0
Open Issues: 1
Metadata Files:
- Readme: README.md
- License: LICENSE

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README

          # Terraform AWS EC2 ASG

This module implements an EC2 Auto Scaling Group

[![](we-are-technative.png)](https://www.technative.nl)

## When to use terraform-aws-ec2-asg

Use `terraform-aws-ec2-asg` if:

- You need to provide a fail-over setup with one EC2 (i.e. the initial use of terraform-aws-ec2-asg).

  - Generally used with `use_floating_ip = true` to host applications that are

    not Dockerized. An EIP will be used and floats to another EC2 instance if

    the current instance fails.

  - Also used for setting up reliable Bastion hosts.

- You need to provide compute resources for ECS clusters.

Do not use `terraform-aws-ec2-asg` if:

- If you need to provision EC2 instances for EKS, we have `eks_custom_nodegroup` for this. (Altough we should/could refactor the `ec2_asg` module for use with EKS as well...) or at least use it in `eks_custom_nodegroup`.

## Todo

- Implement spot instance functionality in `launch_template`.

## Troubleshooting / Known issues

### ARN specified for Service-Linked Role does not exist

Sometimes you receive the following error:

```

│ Error: creating Auto Scaling Group (ec2-asg-website_stack_dev-eu-central-1b): ValidationError: ARN specified for Service-Linked Role does not exist.

│       status code: 400, request id: 3dcf1ff4-d46f-4724-9586-f1e4957b5dd4

│

│   with module.network_compute.module.network.module.nat_instances["eu-central-1b"].module.ec2_asg.aws_autoscaling_group.this,

│   on ../../modules/ec2_asg/autoscaling_group.tf line 16, in resource "aws_autoscaling_group" "this":

│   16: resource "aws_autoscaling_group" "this" {

```

Run `terraform apply` again. This is because of a race condition in AWS.

### Initial lifecycle hooks are not updated in ASG when changed.

We currently do not know a solution other than deleting and recreating the ASG.

## Providers

| Name | Version |

|------|---------|

|  [aws](#provider\_aws) | >=4.8.0 |

|  [random](#provider\_random) | n/a |

## Modules

| Name | Source | Version |

|------|--------|---------|

|  [eip\_lambda](#module\_eip\_lambda) | ./eip_lambda | n/a |

|  [iam\_role](#module\_iam\_role) | git@github.com:wearetechnative/terraform-aws-iam-role | 0fe916c27097706237692122e09f323f55e8237e |

## Resources

| Name | Type |

|------|------|

| [aws_autoscaling_group.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscaling_group) | resource |

| [aws_eip.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/eip) | resource |

| [aws_iam_instance_profile.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_instance_profile) | resource |

| [aws_iam_policy.userdata-lifecycle](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_policy) | resource |

| [aws_iam_role_policy_attachment.userdata-lifecycle](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_role_policy_attachment) | resource |

| [aws_iam_service_linked_role.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_service_linked_role) | resource |

| [aws_kms_grant.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/kms_grant) | resource |

| [aws_launch_template.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/launch_template) | resource |

| [aws_ssm_parameter.public-ip](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ssm_parameter) | resource |

| [random_string.this](https://registry.terraform.io/providers/hashicorp/random/latest/docs/resources/string) | resource |

| [aws_ami.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/ami) | data source |

| [aws_caller_identity.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/caller_identity) | data source |

| [aws_eip.own_eip](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/eip) | data source |

| [aws_iam_policy_document.userdata-lifecycle](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/iam_policy_document) | data source |

| [aws_region.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/region) | data source |

## Inputs

| Name | Description | Type | Default | Required |

|------|-------------|------|---------|:--------:|

|  [additional\_tags](#input\_additional\_tags) | Additional tags on the ASG that will be propagated to the hosts. Useful for EKS & Systems Manager state management. Always propagated to EC2 instances. | `map(string)` | `{}` | no |

|  [ec2\_ami\_name\_filter\_list](#input\_ec2\_ami\_name\_filter\_list) | Optional regex value to filter the AMI image. Most recently is used. Only AMIs with root device EBS and virtualization type HVM are currently allowed. Default is Ubuntu. | `list(string)` | 
[
  "ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"
] | no |

|  [ec2\_ami\_owner\_list](#input\_ec2\_ami\_owner\_list) | Optional list of owners as an additional filter. This is a safeguard to prevent AMI names from being reused by malicious third parties. Default is Canonical. | `list(string)` | [
  "099720109477"
] | no |

|  [ec2\_instance\_type](#input\_ec2\_instance\_type) | Optional instance type for EC2. Defaults to t3a.small. | `string` | `"t3a.small"` | no |

|  [ec2\_root\_initial\_size](#input\_ec2\_root\_initial\_size) | Optional initial size of the EC2 root instance disk. Must be sufficient for the AMI that is used. Defaults to 8Gb. | `number` | `8` | no |

|  [initial\_amount\_of\_pods](#input\_initial\_amount\_of\_pods) | Initial amount of pods to set when the ASG is (re)created. | `number` | `0` | no |

|  [instance\_role\_name](#input\_instance\_role\_name) | Optional instance role name. If not specified a default role with some policies like AmazonSSMManagedInstanceCore will be attached. | `string` | `null` | no |

|  [kms\_key\_arn](#input\_kms\_key\_arn) | KMS key to use for encrypting EBS volumes. | `string` | n/a | yes |

|  [lifecycle\_hooks](#input\_lifecycle\_hooks) | Additional lifecycle hooks for this ASG. They are implemented as initial lifecycle hooks so they will apply to all created EC2 instances. The map key is the name. | map(object({
    timeout_in_seconds = number
    launch_lifecycle = bool
    notification_metadata = string
  })) | `{}` | no |

|  [name](#input\_name) | Unique name for EC2 with ASG setup. | `string` | n/a | yes |

|  [own\_eip\_for\_floaing\_ip](#input\_own\_eip\_for\_floaing\_ip) | Optionally own EIP if floating IP is set to true. | `string` | `null` | no |

|  [security\_group\_ids](#input\_security\_group\_ids) | Optional security groups to be associated with EC2 instances. Make sure that SSM endpoints or WAN access is allowed if you want SSM to work. | `list(string)` | `[]` | no |

|  [sqs\_dlq\_arn](#input\_sqs\_dlq\_arn) | Optionally specify a normal SQS queue to be used as DLQ for EventBridge and Lambda. | `string` | `null` | no |

|  [subnet\_ids](#input\_subnet\_ids) | Required list of subnets to launch instances in. | `list(string)` | n/a | yes |

|  [target\_group\_arns](#input\_target\_group\_arns) | Target groups to add the managed EC2 instances to. | `list(string)` | `[]` | no |

|  [use\_floating\_ip](#input\_use\_floating\_ip) | Use floating IP for standard endpoint entry. | `bool` | `true` | no |

|  [use\_public\_ip](#input\_use\_public\_ip) | Associate public IPs to EC2 instance. | `bool` | `false` | no |

|  [user\_data](#input\_user\_data) | Optional userdata in cleartext.
- Especially if var.user\_data\_completion\_hook is set as well then keep the 16Kb limit in mind for these scripts.
- The script always initiates a server reboot at the end. | `string` | `""` | no |

|  [user\_data\_completion\_hook](#input\_user\_data\_completion\_hook) | Append completion hook to userdata. Make sure you install awscli and jq in the userdata script. This assumes the userdata script is a bash shell script! | `bool` | `false` | no |

|  [user\_data\_lifecyclehook\_timeout](#input\_user\_data\_lifecyclehook\_timeout) | Max timeout on userdata lifecycle hook in seconds. Default to 1800 seconds. | `number` | `1800` | no |

## Outputs

| Name | Description |

|------|-------------|

|  [autoscaling\_group\_arn](#output\_autoscaling\_group\_arn) | n/a |

|  [autoscaling\_group\_name](#output\_autoscaling\_group\_name) | n/a |

|  [elasticip\_parameter\_arn](#output\_elasticip\_parameter\_arn) | n/a |

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